Outline for Dr. Heaton's ESCI 103 class

Principles of Earth Science II or Historical Geology


Textbook: Harold L. Levin, The Earth Through Time, 8th Edition


Chapter 2 – Early Geologists Tackle History’s Mysteries


Key Historical Figures and their Contributions


Herodotus (450 B.C.) and later Leonardo da Vinci (1452‑1519)

         Recognized fossils as remnants of ancient life that lived where the fossils are found


Nicolaus Steno (1638‑1687)

         Principal of Superposition (higher layers of rock are younger than lower layers)

         Principal of Original Horizontality (tilted layers of rock were formed horizontal)

         Principal of Original Lateral Continuity (rock layers are continuous over large areas)


Abraham Werner (1749‑1817)

         Neptunist (believed all rocks, including basalt, precipitated out of the ocean)


James Hutton (1726‑1797)

         Plutonist (believed that igneous rocks formed from a liquid melt)

         Proposed long geologic cycles (like a heat engine) to explain origin of soil for farming

         Father of Uniformitarianism (old earth, gradual change, "present is the Key to the past")

         Principal of Unconformities (sedimentary discontinuities representing time hiatuses)


William "Strata" Smith (1769‑1839)

         Principal of Fossil Succession (using fossils to correlate rock ages)

         Mapped the rocks of England using fossils


Georges Cuvier (1769‑1832)

         Famous anatomist, defender of Catastrophism and mass extinction

         Mapped the rocks of France using fossils


Charles Lyell (1797‑1875)

         Principal expounder of Uniformitarianism, Gradualism, and a cyclic history of life

         Principal of Cross‑cutting Relations (dating of features by their effects on each other)

         Principal of Inclusions (pieces of older rock are encased within younger rock)


Charles Darwin (1809‑1882)

         Follower of Lyell, defender of Uniformitarianism and Gradualism

         Proposed Evolution by Natural Selection to explain faunal succession

         Proposed another evolutionary theory to explain coral reefs


Lord Kelvin (1824‑1907)

         Physicist who claimed that Lyell's earth was an absurd perpetual motion machine

         Claimed that the sun and the earth were rapidly cooling from an original molten state

         Calculated that the earth was too young for Darwin's evolution to take place

         His ideas were negated with the discovery (around 1900) of nuclear reactions


Key Historical Issues

The age of the earth and its features

Rapid catastrophic change vs. slow gradual change

Time's arrow vs. time's cycle

The ultimate cause of things (natural or supernatural)


Historical science requires different approaches than laboratory science

Detailed study of modern processes, comparison with past features (Actualism)

Recognition of past processes no longer operating today

Hypothesis testing, multiple working hypotheses

Chapter 3 – Time and Geology


The Geologic Time Scale: "type sections" named locally and later correlated worldwide

         Hierarchy of Eons, Eras, Periods, Epochs, developed in early 1800's

         Dates in years added in 1950's using radiometric dating


Learn Eons, Eras, Periods, Epochs of Cenozoic, and dates of era boundaries


Stratigraphy is the science of correlating sedimentary rocks.

Geochronology is the science of dating geologic events.


Adam Sedgwick‑‑named Cambrian, used lithology as basis (bad for correlation)

Roderick Murchison‑‑named Silurian, used fossils as basis (better method)

Charles Lyell‑‑named epochs of Cenozoic based on percentage of modern species


Cambrian, Ordovician, Silurian, Devonian: named for places and tribes in Great Britain

Carboniferous: named for the important coal deposits it bears in Europe

         Subdivided into Mississippian and Pennsylvanian in North America

Permian: named for the Ural Mountains that separate Europe and Asia

Triassic: named for the three-fold division of rocks of this age in Germany

Jurassic: named for the Jura Mountains between France and Switzerland

Cretaceous: named for the chalk deposits it contains throughout Europe (and in South Dakota!)

Tertiary and Quaternary: remnant names from the original "Primary, Secondary" nomenclature

Paleogene and Neogene: modern official periods of the Cenozoic Era


         Classification & Hierarchy of Sedimentary Units


Time Units              Time‑Stratigraphic Units              Rock Units

Eon               =       Eonothem

Era                =       Erathem

Period           =       System                               »       Group

Epoch           =       Series                                 »       Formation

Age               =       Stage                                  »       Member

Chron            =       Zone (chronozone)


Lithostratigraphy—using rock type as the basis of correlation

Formations are based on lithology (rock type) and can be "time transgressive"

They also cover a limited geographic area and cannot be correlated worldwide

The trick is relating stratigraphy (rock layers) with time (actual age)


Biostratigraphy—using fossils as the basis of correlation

Fossil zones are the stratigraphic ranges covered by index fossils (short-lived species)


Strategies for aging events

Relative dating‑‑establishing a sequence of events irrespective of time or duration

         Examples: superposition, cross‑cutting relations, fossil correlation, etc.

Absolute dating‑‑giving a date (i.e. in years) to each past event


Requirements of a natural clock

1) Irreversible, non-cycling process

2) Constant or uniformly changing rate

3) Measurable initial condition

4) Measurable final condition


Early (failed) attempts at dating the earth

Rates of deposition & rates of erosion (non‑uniform rate, but did show that the earth was old)

Saltiness of the ocean (involves a cycling process rather than cumulative process)

Heat flow from the earth [Lord Kelvin] (failed to account for heat from radioactivity)


Radiometric dating (works best with igneous rocks)

Atoms, nuclei, protons, neutrons, atomic number, mass number, and isotopes (nuclides)

Radioactive decay, parent isotope, daughter isotope

Types of decay: Alpha, Beta, Gamma, Electron capture

Statistical probability and the law of large numbers


The Half‑life concept: the time required for half the unstable atoms to decay

         Each radioisotope has its own half‑life value which must be experimentally determined.

         Isotopes useful in geology have very long half‑lives because they are dating old events.


Isotopes most useful in dating past events on earth

Uranium‑238     >>     Lead‑206          4.5 billion year half‑life        Multiple α and ß decays

Uranium‑235     >>     Lead‑207          0.7 billion year half‑life        Multiple α and ß decays

Potassium‑40     >>     Argon‑40           1.3 billion year Half‑life       Electron capture

Rubidium‑87      >>     Strontium‑87      49 billion year half‑life         ß decay

Carbon‑14         >>     Nitrogen‑14       5730 year half‑life               ß decay


A closed system is needed to maintain the components and predict the initial condition.

Blocking temperature is the temperature below which a mineral becomes a closed system.

Isochrons are plots from multiple samples that indicate potential problems with the dates.

Concordant dates: similar results from multiple radioisotopes (always good)

Discordant dates: inconsistent results from multiple radioisotopes (sometimes bad)


Know the assumed initial conditions and what event is being dated with each method.

Know what assumptions each dating method is based upon and any potential for error.

Know what type(s) of decay is (are) involved with each method and the half‑life.


Other dating techniques

Fission track dating‑‑counting holes in minerals made by energetic decay products

Magnetostratigraphy‑‑the record of reversals of the earth's magnetic field


Time‑parallel surfaces: ash beds, tillites, magnetic reversals, fossil origins & extinctions

Relative and absolute dating can be used in conjunction with one another to bracket true ages.


Radiocarbon Dating

Carbon-14 is generated in the atmosphere and cycles through the food chain with Carbon-12/13.

When an organism dies its Carbon-14 decays back to nitrogen and escapes into the atmosphere.

Comparing Carbon-14 to Carbon-12 & 13 in a sample tells you when the organism died.

         Chapter 4 – Rocks and Minerals: Documents that Record Earth’s History


Minerals (naturally occurring solids, orderly atomic arrangement and chemical comp.)



         Framework silicates: quartz, feldspars (orthoclase, plagioclase)

         Sheet silicates: biotite, muscovite, chlorite, clay minerals (kaolinite, talc)

         Double chain silicates: amphiboles (hornblende)

         Single chain silicates: pyroxenes (augite)

         Orthosilicates (isolated tetrahedra): olivine, garnet

Carbonates: calcite, dolomite

Phosphates: apatite, turquoise

Sulfates: gypsum, barite

Sulfides: pyrite, chalcopyrite, sphalerite, galena

Chlorites: halite, fluorite

Oxides: hematite, limonite, magnetite, corundum, ice

Native elements: copper, gold, sulfur, graphite, diamond


Igneous Rocks (form from a liquid melt, rocks in bold are most common)


         Felsic: Granite/Rhyolite

         Intermediate: Diorite/Andesite

         Mafic: Gabbro/Basalt

         Ultramafic: Peridotite/Komatiite


         Plutonic (coarse‑grained, intrusive): Granite, Diorite, Gabbro, Peridotite

         Volcanic (fine‑grained, extrusive): Rhyolite, Andesite, Basalt, Komatiite

Volcanic glass: Obsidian, Pumice


Sedimentary Rocks (formed at earth's surface from sedimentary particles, layered)

Clastic sediments‑‑made from fragments of pre‑existing rocks (via erosion)

         Conglomerate/Breccia, Sandstone, Siltstone, Shale, Coal

Chemical sediments‑‑sediments precipitated out of water (organic or inorganic)

         Limestone (Chalk, Coquina, Oolitic ls.), Dolostone, Chert, Rock salt, Rock gypsum

Lithification‑‑occurs by the compaction and/or cementation of sediments

Sorting‑‑the process by which similar clastic particles are collected together

Sedimentary structures‑‑cross bedding, mud cracks, varves


Metamorphic Rocks (recrystallized in the solid state)

Factors: temperature, pressure, intergrannular fluids

Low vs. high grade metamorphism‑‑indicated by index minerals, partial melting

Foliation‑‑planar texture in rock running perpendicular to stress

Settings: burial metamorphism, regional metamorphism, contact metamorphism


Sandstone  >>>  Quartzite (non‑foliated)

Limestone  >>>  Marble (non‑foliated)

Shale  >>>  Slate  >>>  Phyllite  >>>  Schist  >>>  Gneiss (foliated)

Granite  >>>  Gneiss (foliated)

Basalt  >>>  Greenstone (non‑foliated)

Chapter 5 – The Sedimentary Archives


Tectonic Settings

Mountain Belts‑‑areas of recent uplift from either collision or inflation by magma

Cratons‑‑non‑mountainous portion of continents, eroded flat, very old

1) Shields: exposed basement metamorphic complexes, often gneiss intruded by granite

2) Platforms: areas with flat‑lying sedimentary rocks covering the basement complex


Environments of Deposition


Marine Deposition (fine sediments, clastic or biogenous/hydrogenous, great lateral uniformity)

Continental Shelves: shallow water, abundant life, much sediment (much shale & limestone)

Continental Slope: unstable accumulation, erosional canyons formed by turbidity currents

Continental Rise: turbidites form deep-sea fans at base of submarine canyons

Abyssal Plains: slow sediment accumulation covers abyssal hills (very fine clays & oozes)


Transitional Deposition (shoreline, high rates of deposition, clastic sediments from rivers)

Deltas: very thick accumulations of lag gravels, channel sands, backswamp clays and coal

Beaches: longshore drift, clean quartz & magnetite sand accumulation

Barrier Island/Lagoon Sequences: sandstone and coal form in adjacent environments

Tidal Flats: muds carried by tidal waters in areas of constantly‑changing shoreline

(Narrow linear environments along coast, resultant rock units are often time‑transgressive)

(Thick accumulations of sediments can form in shallow water because of subsidence)


Continental Deposition (includes coarsest sediments, mixed local environments)

Meandering Rivers: floodplains, point bars, lag gravels, backswamps, oxbow lakes

Braided Rivers: thick & wide deposits of channel sands

Alluvial Fans/Playa Lakes: coarse conglomerates interfingering with alkali muds

Sand Dunes: crossbeded sands, indicates strong winds and lack of vegetation

Glaciers: tillite (with striated cobbles), loess, associated lake & braided stream deposits

Large Lakes: like continental shelves but with freshwater fossils

Catastrophic Flooding: rare and distinct, scouring of bedrock, well sorted conglomerates


Features of Sedimentary Rocks



Black Coloration: unoxidized organic carbon, FeS2, H2S (poor circulation, organic deposition)

Red Coloration: ferric (oxidized) iron (with evaporites indicate warm & arid conditions)

         Can result from red source rock, subaerial oxidation, or subsurface alteration



Particle size (Wentworth scale), sorting, roundness/sphericity, grain orientation, matrix/cement


Sedimentary Structures (features larger than grains)

Mud cracks: intermittent wet and dry conditions

Cross-bedding: planar (beach and dune deposits), trough (braided rivers sediments)

Ripple Marks: symmetric (oscillating waves), asymmetric (stream or wind currents)

Graded Bedding: fining upward (turbidity currents: coarse fraction settles first, fine fraction last)

Geopetal structures: indicate "up" direction during deposition (ripples, mud cracks, foot prints)

         Chapter 5 – The Sedimentary Archives, cont.


Sandstones (indicate source rock & distance of transportation [maturity])

Quartz Sandstone: rounded quartz grains, other minerals weathered away (long transportation)

Arkose: >25% feldspar (close proximity to granite or gneiss source rock)

Graywacke: poor sorting, fine matrix (fast erosion or high volcanic input, active tectonic areas)

Lithic Sandstone: many rock fragments (deltaic coastal plains, short transportation)


Limestones (carbonates, form in precipitation settings far from clastic sediment sources)

Can be composed of shell fragments, tiny algae fragments, inorganic oöids, etc.

Carbonate Platforms are broad shallow continental shelves dominated by carbonate deposition

During periods of high sea level (Cambrian, Mississippian) carbonate deposition was extensive

Dolomite forms when evaporating sea water develops high concentrations of magnesium


Shales (made of very fine particles derived from erosion, mostly of clay minerals)

Clay minerals form from the weathering of other minerals

These particles are so small that they can be carried great distances suspended in water


Typical Depositional Settings

Sandstone‑-in deltas and beaches (nearest shore)

Shale‑‑near shore where carried by local currents

Limestone‑‑farthest from shore where clay particles are not present to dilute precipitates


Changes in Sea Level

Transgression‑‑a rise in sea level causing flooding ("transgression") of the land

Regression‑‑a fall in sea level causing the exposure of previously drowned land


Transgression sequences: unconformity (bottom), sandstone, shale, limestone (top)

Regression sequences: limestone (bottom), shale, sandstone, unconformity (top)



Disconformity‑‑sedimentary layers are parallel above and below the unconformity

Angular unconformity‑‑sedimentary layers below meet the unconformity at an angle

Nonconformity‑‑igneous or metamorphic rocks underlie the unconformity

Chapter 6 – Life on Earth: What do Fossils Reveal?


Previous assumption: special creation of fixed species, spontaneous regeneration, no extinctions


Georges de Buffon (1707 1788)

         Defined the species concept, observed that environments change species over time

         Noted that characters are inherited in all species, proposed a vague notion of evolution


Carolus Linnaeus (1707‑1778)

         Classified life hierarchically: kingdom, phylum, class, order, family, genus, species


Jean Baptiste de Lamarck (1744‑1829)

         Believed in an automatic regeneration of life (extinctions impossible)

         Believed that life forms evolve with the most complex species being the oldest

         Proposed a mechanism for evolution: the inheritance of acquired characters


Georges Cuvier (1769‑1832)

         Opposed the evolutionary ideas of Buffon and Lamarck, believed in the fixity of species

         Demonstrated the reality of extinction, short‑lived "index fossils" useful time indicators


Louis Pasteur (1822‑1895)

         Demonstrated that life can only arise from existing life (no spontaneous generation)


Charles Darwin (1809‑1882)

         An excellent biological observer from his youth, dabbled in medicine & the clergy

         Converted to the notion of a very old & uniformitarian earth by writings of Charles Lyell

         Voyage of the Beagle (1831‑1836) exposed him to fossils and to island biogeography

         Set a whole new standard for the collection of scientific specimens, meticulous researcher

         Convinced of evolution (descent with modification) of species by "natural selection"


Natural Selection (adapted from socioeconomic theories by Adam Smith & Thomas Malthus)

         Organisms produce far more offspring than the environment can sustain

         Offspring exhibit variation, and these variations are heritable

         Environmental factors "select" which variants survive to produce the next generation

         By sustained selective pressure a species can be radically modified over time

         A gradually changing earth (Lyell) produces gradually changing species (Darwin)


Evidences of evolution (i.e. facts that evolution explains well)

         Historic small‑scale changes within species in nature (natural selection)

         Historic large‑scale changes in domesticated plants and animals (human selection)

         Common body plans and biochemistry in diverse organisms (homologies)

         Common embryologic developmental stages in all vertebrates

         Rudimentary or "vestigial" organs

         Blatant imperfections (maladaptations) and oddities with historical explanations

         Biogeographic distributions (habitat barriers, colonization factors, isolated populations)

         The fossil record (the only true documentation of evolution)

            a) Linking fossils on the large scale (intermediate forms)

            b) The dilemma of the fossil record at the species level

            "Phyletic Gradualism" vs. "Punctuated Equilibrium"

Genetics of Gregor Mendel (1822‑1884)

         Provided the long‑sought basis for inheritance

         At first seemed contradictory to evolution because it limited possible variation

         Eventually formed a foundation for evolution via mutations and genetic recombination

         Disorder of the genetic code (like a jumbled computer program) suggestive of evolution


Inheritance of Acquired Characters has some truth to it

         Human culture is passed on in a Lamarckian fashion

         Immunities (via acquired antibodies, not genes) are often inherited

         Viral DNA and "jumping genes" may sometimes be passed on to offspring


Know the definition and examples of these terms

Divergent evolution‑‑a single species giving rise to morphologically distinct species

Convergent evolution‑‑distant species coming to look superficially alike

Iterative evolution‑‑one lineage repeatedly giving rise to similar descendants

Adaptive radiation‑‑one form quickly giving rise to many diverse descendants

Evolutionary trend‑‑a long‑term evolutionary change in the same direction in a lineage

Sympatric speciation‑‑a single population diverging into two different species

Allopatric speciation‑‑isolated populations of a species diverging to form different species

Preadaptation‑‑a body structure switching from one function to another

Neoteny‑‑a juvenile trait being retained into adulthood

Microevolution‑‑small‑scale changes in a lineage

Macroevolution‑‑development of an entirely new body form or structure

Extinction‑‑the termination of a lineage


Uses of Fossils


1) Learning about ancient life to better understand our world (Paleobiology)


2) Geologic time correlation (Biostratigraphy)

         Index fossils (fossils with a short geologic time range)

         Biozones: range zones, assemblage zones, concurrent range zones

         The problem of reworked fossils


3) Environmental indicators (Paleoecology)

         Subdivisions of the marine and terrestrial realms, habitats

         Ecosystems, trophic levels, niches


4) Reconstructing ancient geography (Paleobiogeography)

         Dispersal (corridors, filter routes, sweepstakes routes)


Body fossils‑‑bodily remains of prehistoric organisms

Trace fossils‑‑tracks, trails, burrows, etc. (Ichnology)


Types of preservation‑‑permineralization, carbonization, etc.

Advantages for preservation‑‑hard parts, rapid burial, etc.

The fossil record (an accidental historical record) is a good but incomplete record of life

The Evolution/Creation Debate


Ideas Popular in Western Religions

God created the universe (primarily for Man) and is the ultimate authority on all matters.

Prophets reveal God's will and purpose; past scripture is a substituted for prophets today.

Argument from Design: the best proof of God's existence is his creations (William Paley, 1802)

Deism: the world is a self‑running machine set in motion by God (René Descartes, 1596‑1650)

Biblical Creationism: the world was created in 6 literal days, a world-wide flood killed most life


The Fundamentals of Science

Observation and Experiment—collecting data from the physical world itself to learn its history

Rational Thinking—careful evaluation, hypothesis testing, theory generation (no higher authority)

Naturalism—the belief that all things have come about by way of consistent natural laws


The Dethroning of God as Creator (finding explanations for origins that don't invoke God)

1) Nebular Hypothesis of Laplace & Kant for the origin of the solar system and the earth

2) Uniformitarian Geology of Hutton & Lyell for the origin of the earth's rocks and features

3) Evolution by Natural Selection of Darwin & Wallace for life on earth


The Genesis Account

1) God created heaven and earth and the various "kinds" of life (Genesis 1:1‑2:7, Exodus 20:11)

2) The Fall of Adam brought death into the world (Genesis 2:16‑17, 3:1‑24, I Cor. 15:21‑23)

3) The Flood of Noah killed off nearly all life on earth (Genesis 6:5‑8:19)


Ways of Harmonizing Geological Observations with Genesis

1) Day-Age Theory: each "day" of Creation is really a long geologic time period

2) Gap Theory: there was a long time gap between the first two verses of Genesis

3) Creation Science: earth is ~6,000 years old, Noah's Flood created the sedimentary rocks


Spectrum of Positions on Science and Religion

1) Atheistic Evolution: evolution is the only explanation needed for life on earth

2) Theistic Evolution: evolution is true, but God guided the process (Catholic viewpoint)

3) Day-Age & Gap Theories: evolution is false but there were long geological ages

4) Creation Science: the earth is young, Noah's Flood deposited most sedimentary rocks


The History and Nature of Creation Science

Originated with a Seventh Day Adventist named George McCready Price (1870‑1963)

         Price differed from other creationists by attacking geology rather than biology.

Made popular to Protestants by Whitcomb & Morris' The Genesis Flood (1963) & Jerry Falwell

Morris' Scientific Creationism presents Creationism as a Science rather than a religion.

         Science is the modern way of knowing all truth, so even religion must be scientific.

         Creationists have tried (unsuccessfully) to get Creationism into the science classroom.


Creationism in Court

1) Tennessee Anti-Evolution Act (1925) prohibited the teaching of evolution in public schools

         Scopes Monkey Trial at Dayton resulted (William Jennings Bryan vs. Clarence Darrow)

2) Equal Time laws (equal time required for evolution and Biblical view of origins)

         These were ruled unconstitutional at the outset because of Separation of Church and State.

3) Arkansas Balanced Treatment Act (1981) based on the Evolution/Creation science distinction

         Judge Overton banned implementation of the law because of its obvious religious basis.


Creationist Societies

Religion and Science Association (1935‑1937): All camps represented, failed over disagreements

Deluge Geology Society (1938‑1947): Mostly Adventists, all believers in Flood Geology

American Scientific Affiliation (1941‑present): Gradually came to accept theistic evolution

Creation Research Society (1963‑present): Membership requires M.S. and acceptance of a creed

Institute for Creation Research (1970‑present): The center of modern creationism, San Diego, CA


Creationist Strategies

Attack evolution as the cause of all social ills (crime, homosexuality, communism, etc.)

Attack evolutionary science (intermediate fossils, geological sequences, radiometric dating)

Appeal to the Second Law of Thermodynamics (argue that evolution violates that law)

Claim there are only two possible models, so disproving one proves the other to be true

Tune arguments and examples to education level of the audience

Use debate platform to argue their case (Duane T. Gish is a prominent debating creationist)

Never propose a comprehensive theory for opponents to evaluate and compare with their own


Is Creation Science Really Scientific?

Creationists claim it is because they appeal to scientific laws, observations, and principles to support their theory. They also claim that evolution is as much a religion as their position is. Their books contain mostly scientific arguments (mostly trying to discredit scientific viewpoints).


Mainstream scientists discount Creationism as a science because it begins with religious conclusions and then only accepts the "evidence" that supports them (they never test hypotheses and accept the results), and because most creationist claims (young earth, world-wide flood, etc.) were proven false (based on scientific observations) almost 200 years ago.


Most scientists, philosophers, and legal experts see Creation Science as a political movement by conservative Christian fundamentalists to advance their cause and oppose atheism. However, about half of Americans believe the creationist position, and a majority feels that both evolution and creation should be taught in the public schools to expose students to both positions.


Intelligent Design: a new brand of Creationism

Intelligent Design proponents seek scientific evidence for the existence of God but do not make any other conclusions (no claims about the age of the earth, the truth of evolution, etc.). Most proponents are theistic evolutionists and other liberal Christians rather than Fundamentalists.


Michael Behe: argued that certain biochemical machines have Irreducible Complexity

William Dembski: said random and non-random causes can be distinguished by Design Inference

Phillip Johnson: Berkeley law professor who wrote Darwin on Trial attacking Naturalism


Most traditional scientists oppose Intelligent Design because 1) these arguments are just a rehash of old ideas that were thoroughly addressed by Darwin and others long ago, and 2) accepting these arguments leads nowhere because the "intelligent designer" is not known well enough to apply as a causality in any kind of scientific research study.


Other Comments on the Conflict between Science and Religion

Science struggles over the origin of life, whereas death needs no special explanation.

Religion needs no explanation for the origin of life, but it struggles over the issue of death.


Humans used to view all actions imposed on them as "Acts of God" (good weather, bad weather, lightning, etc.), whereas now we attribute all such immediate actions to natural causes. Only very big things are still sometimes attributed to God's will (our origin, birth, and death).


Science is about understanding cause and effect, discovering new phenomena, and revealing the history of the universe. Prophets, scriptures, and psychics have not been helpful in making scientific discoveries or breakthroughs, whereas exploration, experiments, and brainstorming have been very helpful. It is therefore logical to view supernatural sources of information as invalid or irrelevant.


Naturalism (the idea that only natural causes can be accepted) is a philosophy, a procedural strategy, and a religion (effectively atheism). It is therefore a murky legal and political issue as to where good science ends and the religion of atheism begins.

Chapter 7 – Plate Tectonics Underlies All Earth History


Paradox of thickest sedimentary sequences being found in highest mountain belts

Early theories sought a cause & effect relationship between the two (vertical tectonics)


Continental Drift theory of Alfred Wegener (horizontal tectonics, focus on continents)

‑Geographic fit of continents like puzzle pieces

‑Continuation of geographic or stratigraphic features across widely‑spaced continents

         Mountain ranges like Appalachians

‑Sedimentary sequences including lake deposits and tillites

         Glacial‑striated rocks that are paradoxical in their current positions

‑Odd positioning of late Paleozoic climate indicators

         Tillites and glacial striations near the equator on South America and India

         Thick coal deposits and trees without annual growth rings in Eurasia and United States

         Evaporite deposits in northern Europe and United States

         Coral reefs in the United States and Eurasia

‑Strange biographic patterns of Paleozoic fossils

         Tropical Glossopteris flora found on all Gondwana continents

         Terrestrial reptile Lystrosaurus found on all Gondwana continents

         Freshwater reptile Mesosaurus found only on Africa and South America

‑Strange biogeographic patterns of modern animals (some false evidences)

         Similar earthworms, lungfishes, and flightless birds on Gondwana continents

         Anteaters found on South America, Africa, and Australia (really convergence)

         Similar mammalian faunas on North America and Eurasia (really from Bering Strait)


The alternate biographic theory of Land Bridges and why Wegener correctly rejected it

Bimodality of the earth's crust (basaltic oceanic vs. granitic continental crust), isostatic balance

The failed search for a mechanism to drive horizontal continental movements


Sea‑floor Spreading concept of 1950's (ocean centered, based on knowledge of seafloor)

Paleomagnetism: Earth's magnetic field, remnant magnetism in basalt, apparent polar wandering

Parallel symmetric magnetic stripes on the sea floor: the search for an explanation

The Vine/Matthews hypothesis, Morley's manuscript rejected!


Plate Tectonics (a unifying theory for geology, explaining all features of the earth's crust)

"Floating" lithospheric plates of continental and/or oceanic crust moving horizontally

Plate movement driven by convection currents in mantle, ridge push, slab pull


1) Divergent plate boundaries: mid‑oceanic ridges and continental rifts

2) Transform plate boundaries: transform faults, the San Andreas Fault

3) Convergent plate boundaries: deep‑sea trenches, island arcs and andesitic mountains

         a) Ocean/ocean collisions, b) continent/ocean collisions, c) continent/continent collisions


Plate boundaries site of mountain ranges, volcanos, and earthquake epicenters

Hot spot island chains (Hawaiian Islands): not a plate boundary, but shows plate movement

Allochthonous or accreted terrains (Alaska): formation of large continent from small islands


Origin of the Earth's Crust

1) Oceanic crust is formed from partial melting of the mantle below mid‑oceanic ridges.

2) Continental crust is formed from partial melting of oceanic crust in subduction zones.

         Continental crust with its lower density will not subduct and therefore "lasts forever."

         Chapter 8 – Earliest Earth: The Hadean and Archean Eons


Universe mostly Hydrogen & Helium; Earth mostly Iron, Oxygen, Silicon, Magnesium

Heavy elements created in supernova explosions, recycled into new solar systems


Origin of the solar system: Solar nebula hypothesis of Kant and Laplace

         The solar system began as a nebula of hydrogen, helium, and a trace of heavier elements

         Contraction caused spinning by conservation of angular momentum

         Contraction converted gravitational potential energy to heat, igniting fusion in the sun

         Planetesimals formed in nebula and fused by gravity to form protoplanets

         Solar winds blew the hydrogen and helium off the inner (terrestrial) planets

         The forming planets swept up most of the excess debris in the solar system



Ordinary chondrites: ferromagnesian silicates (like earth's mantle) & spherical chondrules

Carbonaceous chondrites: chondrites with 5% organic compounds, same composition as sun

Achondrites: chondrites lacking chondrules

Iron meteorites: crystals of iron‑nickel alloy (like earth's core)

Stony‑iron meteorites: mixture of silicates and iron‑nickel


Radiometric age of meteorites: up to 4.566 billion years


The Moon

Large for the size of the planet it orbits, ¼ size of earth, 1/6 gravity of earth, no atmosphere

Theories of origin: simultaneous creation with earth, separated from earth, captured by earth

Orbital and axial cycles the same, so one side always faces earth

Cratered highlands of anorthosite (4.6‑4.0 b.y. old), maria basins of basalt (3.8‑3.2 b.y. old)

Unconsolidated lunar regolith ("soil") from impacts blankets the moon, micrometeorites

The moon is a museum of the solar system's early history, nothing to obliterate old features


Other Inner or "Terrestrial" Planets

Mercury: similar to earth's moon but without maria, close to sun


Venus: similar in size to earth, thick carbon dioxide atmosphere, 475° surface temperature

         Lack of oceans prevents incorporation of carbon dioxide into carbonate rocks

         Lack of liquid water prevents hydrologic erosion

Continent‑like highlands, large volcanoes, and rolling hills are present, so internally (tectonically) Venus appears to be much like the earth


Mars: ½ the diameter of earth, thin atmosphere, giant volcanoes

         Winds create dust storms and create a desert‑like landscape

         Ice caps show presence of water, evidence of past stream erosion, no oceans


Outer Planets or Gas Giants

Jupiter: largest planet in solar system, thick stormy atmosphere

Saturn: similar to Jupiter, has prominent ring system

Uranus and Neptune are smaller gas giants

Pluto and the moons of the gas giants are similar to the terrestrial planets


Studying Earth's interior

         Density of the earth: 5.5 g/cm3 for whole earth, 2.8 g/cm3 for crustal rocks

         Earth's magnetic field: requires iron in motion

         Seismic waves and their shadow zones

            Primary waves: particles move parallel to wave motion, circular shadow zone

            Secondary waves: particles move perpendicular to wave motion, ring shadow zone

            Surface waves: particles move in circles along surface of earth, local only


Mohorovicic discontinuity: base of earth's crust, top of earth's mantle (5‑70 km deep)

Seismic low velocity zone: partly molten region in upper mantle (100‑170 km deep)

Gutenberg discontinuity: base of silicate mantle, top of metallic core (2900 km deep)


Inner Core: Solid iron and nickel (intense pressure keeps it in the solid state)

Outer Core: Liquid iron and nickel (intense heat keeps it in the liquid state)


Mantle: Ultramafic rocks (peridotite and komatiite) composed of mafic minerals like olivine


Asthenosphere: partly molten low velocity zone, source of magma, drives tectonic plates

Lithosphere: crust and mantle above low velocity zone, moves in pieces called tectonic plates


Oceanic crust: thin (5‑12 km), dense (3.0 g/cm3), dark (basaltic), young (<200 M.Y.)

Continental crust: thick (35‑70 km), less dense (2.7 g/cm3), light (granitic), old (<4 B.Y.)


The earth probably began as a uniform body but underwent differentiation into layers as gravity pulled the densest components to the core and let the lightest components float to the surface


Earth's Atmosphere

1) Hydrogen/helium blown away by solar winds from young sun

2) Water/nitrogen/carbon dioxide from volcanic outgassing and/or carbonaceous chondrites

3) Nitrogen/oxygen from photochemical dissociation and photosynthesis (allowed ozone layer)


Banded iron formations exist from the second atmosphere, most over 3 B.Y. old

Red beds of oxidized iron become abundant at about 1.8 B.Y. ago


Current atmosphere: 78% Nitrogen (N2), 21% Oxygen (O2), 1% Argon (Ar), 0.03% CO2


Outgassing also produced ocean water and carbonate/sulfate rocks (excess volatiles).


Carbon dioxide & water vapor in atmosphere cause a warming "greenhouse" effect: solar energy (visible light) enters atmosphere freely, but escaping energy (infrared light) is held by the atmosphere and released slowly.


Origin of Life and the Earliest Fossils

Conditions of the primitive atmosphere and ocean very different from today

Urey and Miller Experiment has produced amino acid chains inorganically

Proteins (long amino acid chains) and nucleic acids necessary for life

Basis of life is the ability to replicate (reproduce)

Experimental microspheres formed of proteinoids resemble cells


Heterotrophs probably developed first and consumed organic soup of early oceans

Autotrophs developed the ability to derive energy from inorganic chemicals and from sunlight


Anaerobic respiration (fermentation) is an inefficient energy process

Aerobic respiration (using oxygen) is much more efficient


Prokaryotic cells vs. Eukaryotic cells and the Endosymbiotic Theory

The earliest fossils: tiny cells, filaments, and stromatolites

Chapter 9 – The Proterozoic: Dawn of a More Modern World


Precambrian time: named by Sedgwick for "basement" rocks and "pre‑fossil" strata

Turns out to comprise 87% of earth history, to have a record of primitive life


Early classification

Hadean Eon: earliest (4.6‑4.0 B.Y.), no surviving rocks, probably many meteorite impacts

Archean Eon: middle (4.0‑2.5 B.Y.), highly metamorphosed rocks ("basement" of continents)

Proterozoic Eon: later (2.5‑0.5 B.Y.), early "non‑fossiliferous" sedimentary rocks


Degree of metamorphism turns out not to be a good measure of age, but eon names still used


Classification of Continental Areas

Mountain Belts‑‑areas of recent uplift from either collision or inflation by magma

         Mountain building events (orogenies) are what lead to regional metamorphism


Cratons‑‑non‑mountainous portion of continents, eroded flat, very old

1) Shields: exposed basement metamorphic complexes, often gneiss intruded by granite

         These are the deep roots of ancient mountain belts exposed by long‑term erosion

         Zones of uniform age represent various old orogenies, are called Precambrian Provinces

         Sometimes cut by failed rift systems containing normal faults and basalt dikes and flows

2) Platforms: areas with flat‑lying sedimentary rocks covering the basement complex


Origin of Oceanic Crust

Mafic basalt derived from ultramafic mantle in rift zones (divergent plate boundaries)

Replaced an assumed original ultramafic crust, disrupted by mantle convection and meteorites


Origin of Continental Crust

Formed slowly and locally by partial melting of descending basalt slabs in subduction zones

These small, low‑density felsic zones collided and grew to form mountainous continents

Subduction zones along continental margins inflated them with additional felsic magma

Mountain belts take at least half a billion years to erode flat to form cratons

Large continents were present on earth by the late Archean (most basement rocks > 2.5 B.Y.)


Earth during the Archean (different than today; uniformitarianism difficult to apply)

Shallow oceans overlying thin, actively‑moving basaltic crust (early oceanic crust)

Small protocontinents forming as island arcs, fusing by collisions to form continents

Continents mountainous with small cratons and virtually no continental shelves

Back‑arc structural basins filling with sediments and volcanics formed greenstone belts

Greenstone belts grade upward from ultramafic to felsic volcanic sediments, intruded by granite

Upper Sediments sometimes contain unoxidized Banded Iron Formations (rich iron ore)

Witwatersrand Basin in South Africa is greenstone belt containing half the world's gold deposits


Earth during the Proterozoic Eon

Transition to a more modern tectonic style including large continental masses.


Large cratons had formed via long-term erosion by the end of the Archean, allowing continental shelves and epeiric seas (like modern Hudson Bay).


Tills in the Gowganda Formation of Ontario indicate a period of early Proterozoic glaciation.


Worldwide tills of late Proterozoic age indicate world-wide glaciation 700‑800 M.Y. ago.  This may have resulted from a accumulation of continents along the equator.


Proterozoic sediments include both immature graywackes (from volcanic sediment) and mature quartz sandstones (from weathering of granite and gneiss), indicating larger and more stable continents.  Limestones with stromatolites (algal mats) are also present, showing that primitive life was abundant in broad shallow seas.  Banded Iron Formations give way to red beds during the Proterozoic, indicating the presence of free oxygen in the atmosphere.


Precambrian History of Laurentia (proto North America)

Most Precambrian Provinces formed in the Archean and fused together by 1.9 B.Y. ago.


The Wopmay Orogeny added another microcontinent to NW Laurentia about 1.8 B.Y. ago.


Continents collided in Mazatzal Orogeny to form the first supercontinent about 1.4 B.Y. ago.


Large‑scale rifting broke up this supercontinent 1.2 B.Y. ago (Keweenawan Rift a remnant).


A continent to the SE collided with Laurentia in Grenville Orogeny about 0.9 B.Y. ago.


Laurentia was mostly stable during late Proterozoic, leading to thick sedimentary accumulation:

         Belt Supergroup (Western North America, famous for its later thrust faulting)

         Grand Canyon Supergroup (exposed in Grand Canyon below the angular unconformity)

         Animikie Group (Eastern Canada, contains BIFs and fossiliferous Gunflint Chert)


Other Continents during the Precambrian

Gondwanaland formed during the Proterozoic and was the world's largest continent.


The Andes (South American edge of Gondwanaland) were already forming in the Proterozoic.


The Tasman Orogenic Belt of eastern Australia formed at opposite end of Gondwanaland.


What is now Eurasia was several separate, small continents.


Life of the Proterozoic

Stromatolites become widespread and abundant in Proterozoic, due in part to continental shelves


The origin of the eukaryotic cell was the first great evolutionary event of the Proterozoic


Acritarchs seem to represent planktonic algae in a resting phase with a hard cell wall


Ediacara Fauna: the first large organisms, shaped like pancakes, ribbons, and threads

These sort‑bodied organisms are preserved in sandstone because there were no scavengers


Glaessner interpretation: Ediacaran species are primitive forms of modern animal phyla

Seilacher interpretation: Ediacaran fauna is a separate, failed radiation of life


The origin of animals (or any large organisms) and the problem of surface area to volume ratio

Why be big?

Chapter 10 – Early Paleozoic Events


Plate Tectonic Configuration in the Cambrian

Paleomagnetics reveal orientation and latitude of continents but not longitude

Laurentia (proto North America) was at the equator & turned 90° from its present orientation

Other small continents: Baltica (proto Europe); Siberia, China, and Kazakhstania (proto Asia)

The giant Gondwanaland was at the equator but was headed south


The continents were all close together but were moving apart after a late Proterozoic breakup

Vendian normal faults and basalt intrusions around the continental margins demonstrate this

The Cambrian was a quiet time tectonically: no continental collisions & little mountain building

The Paleozoic Era is marked by the opening then closing of the "Iapetus Ocean" of eastern N.A.


Sedimentary Rocks of the Early Paleozoic

Four major Paleozoic transgression/regression cycles in North America:

         1) Sauk (Cambrian/Ordovician)

         2) Tippecanoe (Ordovician/Silurian)

         3) Kaskaskia (Devonian/Mississippian)

         4) Absaroka (Pennsylvanian/Permian)


Low sea level is indicated by widespread unconformities separating deposits of these cycles.

High sea level is indicated by widespread marine sedimentation on the continent, especially limestone (i.e. when water covers most of a continent, there is little exposed land to produce clastic sediments and much shallow water for animals to live & grow skeletons).


Arches‑‑high areas that receive deposition only during the highest sea levels, prone to erosion

Basins‑‑low areas under nearly constant deposition that accumulate great thickness of sediment

Aulacogens‑‑large grabens from rifting that receive thick sedimentary deposition


Cambrian transgression (base of Sauk Cycle) left a classic transgression sequence:

         1) Unconformity (old erosional land surface), 2) Sandstone, 3) Shale, 4) Limestone

The sea advanced across the continent at about ½ an inch per year during the transgression

Cambrian rock thicknesses: 5000 m in California, 500 m in Arizona, 50 m in Colorado

Only a narrow Transcontinental Arch was left above water (no deposition) by late Cambrian

This explains why Cambrian rocks exist in western but not eastern South Dakota (Arch in Iowa)

Sediments along Transcontinental Arch are near‑shore facies (sandstones, e.g. Wisconsin Dells)

The Arch may have always been above water or experienced alternating deposition and erosion


Basal sandstones are derived from continental areas via river, wind, and beach transport

The lack of any land plants during the Cambrian subjected sediments to constant transportation

Long periods of current, wind, and wave action created very mature quartz sandstones

Different kinds of ripple marks indicate final deposition by wind, rivers, or ocean waves


Overlying shales formed from smaller rock fragments (mostly clay minerals) washed offshore


Most marine invertebrates like warm, shallow (lighted & oxygenated), sediment‑free ocean water

The abundance of such conditions during the Cambrian must have helped early animals diversify

Most Cambrian limestones are made up primarily of shell fragments (clastic limestones)

Warm, shallow, wave‑agitated waters led to inorganic precipitation of some oolitic limestones

Sometimes the inland seas became hypersaline from evaporation (leading to low animal diversity)

The Ordovician Ocean (Laurentia)

The Sauk Sea regressed in the early Ordovician, leading to a widespread disconformity.

The Tippecanoe Sea transgressed in the later Ordovician and covered virtually all of Laurentia.

The base of the Tippecanoe is the St. Peters Sandstone, covered by extensive limestones.

There is also a very extensive black shale layer loaded with graptolites (graptolitic shale facies).

Niagara Falls is eroding a sandstone/shale/limestone sequence from the Tippecanoe Cycle.


Tectonic Events of the Ordovician (Laurentia)

Western North America (northern Laurentia) remained a quiet trailing continental margin.

The Iapetus Ocean of eastern North America (southern Laurentia) began to close via subduction.

A huge volcanic eruption left a meter‑thick ash layer over much of North America and Europe.

Subduction‑related vulcanism created an island arc (microcontinent) just south of Laurentia.

The collision of this microcontinent with Laurentia caused the Taconic Orogeny (first of three orogenies that formed the Appalachians) and created a huge wedge of clastic sediment.

The Taconic Orogeny is the same as the Caledonian Orogeny of Scotland and Norway.

(Modern analog of the Taconic Orogeny are found in Indonesia and southern Europe.)


Tectonic Events of the Ordovician (Elsewhere)

Baltica and Siberia were approaching each other, closing the Uralian Seaway by subduction.

Gondwanaland moved south, with the present‑day Sahara Desert glaciated over the south pole.

The resulting lowering of global sea level helped cause the Late Ordovician mass extinction.


The closing of the Cambrian seaways (Iapetus Ocean and Uralian Seaway) brought together landmasses (and their Cambrian fossils) that formed in distant locations.  The trilobite Paradoxides was named for its paradoxical distribution (only Europe and New England).

Chapter 11 – Late Paleozoic Events


Beginning the Assembly of Pangea

Baltica and Laurentia collided to form Laurussia (Acadian/Caledonian Orogeny, Devonian)

This uplifted the northern Appalachians and the Caledonian mountains of Scandinavia

Thick clastic wedges in NE United States (Catskill Delta) and Great Britain (Old Red Sandstone)


Kaskaskia Sea formed Chattanooga Shale adjacent to Catskill Delta, carbonates farther west

Transcontinental arch still a highland in central United States, no deposition there

Williston Basin in northwestern North America at equator, rimmed by reefs and evaporites


Island arc collided with Laurentia (Nevada/Idaho region) in Antler Orogeny (Devonian)


Gondwanaland joined Laurussia (Allegheny/Hercynian Orogeny, Pennsylvanian)

Kazakhstania, Siberia, then China joined Laurussia to form Pangea (Permian/Triassic)


Mississippian Period in Laurussia

Acadian and Antler Mountains eroded down somewhat, no new collisions, less clastic sediment

Continent‑wide inland Kaskaskia Sea between E and W mountains, clean limestone deposition

         Most caves in the USA (including Black Hills) have formed in Mississippian limestone.

A late Mississippian regression (of Kaskaskia Sea) left a widespread unconformity in the United States; this is why the Carboniferous is divided into Mississippian and Pennsylvanian.


Pennsylvanian Period in Laurussia

Collision of Gondwanaland with Laurussia formed Appalachian/Ozark/Ouachita Mountains


Transgression of Absaroka Sea, repeated small transgressions/regressions formed Cyclothems (~50 non marine/coal/marine sequences) in the eastern United States (possible from glacial cycles in Gondwanaland).


Regional uplifts and basins in the western United States led to thick local deposition of sands, shales, and impure limestones, often in repeating cycles.


In Europe the entire Carboniferous system has extensive coal deposits.


Permian Period in Laurussia

Uplift of Appalachian/Ozark/Ouachita Mountains continued but finally ended in late Permian

Subduction along the western margin of the United States formed volcanos.

Absaroka Sea slowly retreated, leaving restricted basins in which evaporite deposits formed.

The late Permian was a time of very low sea level, much like today.

Chapter 12 – Life of the Paleozoic


Tommotian Fauna: tiny shelly fossils of the latest Proterozoic, prelude to Cambrian Explosion


Life of the Cambrian

First complex animals with hard skeletons, restricted to oceans, evolutionary rates very high

Dominated by trilobites and other arthropods, inarticulate brachiopods, and weird echinoderms

Sponges (Porifera) are the simplest large animals, each cell being identical

Archaeocyathids (cup animals) took over from stromatolites as the main structural reef formers


Burgess Shale Fauna (middle Cambrian) shows there were many strange soft‑bodied creatures

Anomalocaris of the Burgess Shale appears to have been the first big carnivore


Most of these animals went extinct before the end of the Cambrian; trilobites were reduced


The Cambrian was a time of experimentation with basic body forms.

The Ordovician was a time of standardization and specialization.


Cambrian Fauna                                                           Ordovician/Paleozoic Fauna

Anomalocaris (top carnivore)                                      Eurypterids (top carnivores)

Archaeocyathids (reefs)                                                Rugose and tabulate corals (reefs)

Trilobites                                                                      Bryozoans (reefs)

Inarticulate brachiopods (unhinged)                               Articulate brachiopods (hinged)

Weird echinoderms                                                       Burrowing bivalves

Weird Burgess Shale creatures                                      Crinoids ("sea lilies" with long stalks)

                                                                                    Graptolites (floaters)


The first vertebrates (jawless fishes called Ostracoderms) appeared in the Ordovician.

The land was still completely barren during the Ordovician.

A mass extinction in late Ordovician killed off many invertebrate families but no major groups.


The Paleozoic Marine Fauna

Rugose and tabulate corals, bryozoans, and stromatoporoids the main structural reef formers

Crinoids, articulate brachiopods, and molluscs (gastropods, bivalves, cephalopods) also common

         Important shelled cephalopods: nautiloids, ammonoids (goniatites and ceratites)

Graptolites and conodonts are two hard‑to‑interpret animals that provide excellent index fossils

Asteroids (star fishes) and cephalopods were also important predators


The Origin of Vertebrates

Pikaia of the Burgess Shale is the first known chordate, similar to living Amphioxus

Vertebrae replaced the notochord as main structure, myotomes (muscle blocks) cause propulsion

Disarticulated fish scales are found in the late Cambrian

Ostracoderms are armored jawless fishes of the early Paleozoic, like living lampreys & hagfishes

Jaws formed as modified gill arches, gave vertebrates predatory advantage

Four classes of jawed fishes arose in Silurian/Devonian: Placoderms (armored fishes), Chondrichthyes (cartilaginous fishes: sharks, skates, rays), Acanthodians (spiny fishes), Osteichthyes (bony fishes: most modern fishes)

Two kinds of osteichthyes developed: ray‑fin fishes (no lungs, most diverse) and lobe‑fin fishes (lungfishes, coelacanths [like Latimeria], and rhipidistians [gave rise to amphibians])

Devonian "age of fishes," Ostracoderms and Placoderms gone by end of Devonian


The Invasion of the Land

Living on land requires a waterproof "skin" and structural support to resist force of gravity

Green algae (Chlorophytes) probably gave rise to land plants, though little similarity exists

A vascular system developed to distribute water from the ground and food from above ground

Simple psilophytes appeared in Silurian, began stabilizing ground and forming soil

Devonian and Carboniferous dominated by lycopods, sphenopsids, ferns (formed coal deposits)

The first seed plants were the "seed ferns" (including Glossopteris) of the late Carboniferous

Primitive gymnosperms (ancestors of conifers) and ginkgoes arose in the Permian

Insects arose from marine arthropods and became very large; many flying forms


The Origin of Amphibians

Ichthyostega appeared in Devonian; shares limb structure, skull bone structure, labyrinthodont teeth, and tail fin with rhipidistian fishes

Labyrinthodont amphibians of late Paleozoic became large predators of fish and insects

Lepospondyls are odd small amphibians of Paleozoic, some had boomerang‑shaped heads

Anthracosaurs developed into reptiles

Major groups classified by the structure of the vertebral centrum


The Origin of Reptiles

Development of amniotic egg (equivalent to seed in plants), complete divorce from water bodies

Major groups classified by temporal openings in skull: anapsids (stem forms, turtles), synapsids (mammal‑like reptiles, some with "sails"), diapsids (includes lizards, snakes, dinosaurs)

Took over most niches from amphibians by end of Paleozoic, synapsids particularly dominant


The Great Permian Extinction

Complete extinction of trilobites, rugose and tabulate corals, fusulinids, acanthodian fishes

Heavy losses by brachiopods, bryozoans, crinoids, ammonoids, synapsid reptiles

Chapter 13 – Mesozoic Events


Breakup of Pangea

Gondwanaland separated from Laurasia (North America, Europe, Asia), leaving Florida behind

Gondwanaland and Laurasia broke up from east to west, and the Atlantic Ocean began opening

Africa moved north, closing the Tethys Sea into its remnant, the Mediterranean Sea

India moved north, Australia moved east, and Antarctica moved south to form the Indian Ocean

Panthalassa shrunk by subduction at its edges to produce the modern Pacific Ocean


Evidence of Triassic rifting abundant in Newark Group of eastern United States

Normal faults, alluvial fan redbeds (with dinosaur footprints), and basalt flows are common


The newly‑opening Gulf of Mexico was a restricted basin that accumulated Jurassic evaporites

         The resulting salt domes of the Gulf Coast are excellent petroleum and natural gas traps


Sonoma Orogeny

An island arc collided with western North America to form a long cordilleran mountain belt

Many such "displaced" or "accreted" or "exotic" terranes exist from California to northernmost Alaska and added significant area to the North American continent

Mountains formed by these collisions shed large volumes of sediment to the continental interior

Further subduction along the coast emplaced large batholiths of granite now exposed in the Sierra Nevada Mountains, and this event is called the Nevadan Orogeny


Triassic Period in North America

An unconformity exists almost everywhere between Permian and Triassic formations

The Triassic is famous for continental (non‑marine) redbeds formed from eroding sediments of the Appalachian and Sonoma highlands

The Moenkopi Formation is a classic redbed shale/limestone in the Four Corners region

The overlying Chinle Formation is famous for its plentiful petrified wood and uranium deposits


Jurassic Period in North America

The Navajo Sandstone of the Four Corners region is a famous wind‑blown sand deposit

The Sundance Sea invaded the central U.S. from the north & deposited the Sundance Formation

Sediments silted up the Sundance Sea and formed the swampy deposits of the Morrison Formation, famous for its Jurassic dinosaur fossils (including the largest land creatures)


Cretaceous Period in North America

An early Cretaceous transgression formed a northern and southern sea that didn't meet

A late Cretaceous transgression formed a continuous seaway north to south across the continent

Coal formed from swamp deposits along the coasts of the sea, and dinosaurs were abundant

The interior (including South Dakota) accumulated marine sediments from the sea, most notably the Dakota Sandstone (sand of early transgression), the Niobrara Chalk (similar in age & rock type to the White Cliffs of Dover in England), and the Pierre Shale (famous for its ammonoid and marine reptile fossils as well as bentonite deposits)


Mesozoic climates were warm and equable, no glaciation anywhere

Continents were separating but were still close together

Chapter 14 – Life of the Mesozoic


Plant Life

New marine phytoplankton: Coccolithoforids, Silicoflagellates, Diatoms

Gymnosperms (naked seed plants) dominant on land: Cycads, Ginkgoes, Conifers

Angiosperms (flowering plants, enclosed seeds) first appear in the Cretaceous



Foraminifera (unlike Paleozoic fusulinids) undergo adaptive radiation

Rudist bivalves shaped like horn corals dominate many reefs

Scleractinian corals dominate reefs in tropical waters of Tethys Sea

Bivalves dominate over brachiopods after Permian extinction

Ammonite ammonoids with complex sutures make excellent Mesozoic index fossils

Belemnites were a group of cephalopod molluscs with internal chamber skeletons

Echinoids (sea urchins) join starfishes as prominent echinoderms


Terrestrial Vertebrates (Mesozoic "Age of Reptiles")

Synapsid reptiles decline in Triassic but give rise to mammals before disappearing

Therapsid/mammal transition gradual, reptile jaw articulation bones become middle ear bones

Mammals develop teeth with precise occlusion for chewing their food, teeth good index fossils

Mammals remain small and inconspicuous (probably all nocturnal) during the Mesozoic


Diapsid reptiles, especially archosaurs (ruling reptiles), take over all the big land niches

Thecodonts (early archosaurs) were bipedal runners that gave rise to crocodilians, phytosaurs, pterosaurs, saurischian and ornithischian dinosaurs, and birds

Saurischians ("lizard hip" dinosaurs) include the great carnivorous bipeds (Theropods) like Tyrannosaurus and the gigantic quadrupeds (Sauropods) like Apatosaurus

Ornithischians ("bird hip" dinosaurs) include the armored and bizarre dinosaurs like Stegosaurus, Ankylosaurus, Triceratops, and the dome head and duck bill dinosaurs

Triassic dinosaurs were small, Jurassic dinosaurs included the giant sauropods (the largest land animals of all time), and Cretaceous dinosaurs were the most diverse and bizarre

The great dinosaur controversy: were they warm or cold blooded, active or sluggish


Marine Reptiles

Ichthyosaurs were the most fish‑like, totally aquatic, used live birth in the water

Placodonts were clam crushers similar to modern walruses, lived only in Triassic

Plesiosaurs swam with limbs as paddles, some had long necks, up to 40 feet long

Mosasaurs were giant sea‑going varanid lizards of the Cretaceous

There were also giant marine crocodiles and turtles


Avian Reptiles and Birds

Pterosaurs were primarily gliders, supported membrane on elongate little finger, includes largest flyers with wingspan up to 50 feet, some had aerodynamic head crests

First bird Archaeopteryx from the Jurassic Solenhofen Limestone of Bavaria, evolved from thecodonts or early theropod dinosaurs, basically a reptile with feathers (lacks all bone fusions and other skeletal specializations of modern birds)

True flight developed three times in vertebrate history (pterosaurs, birds, bats), but each group turned the vertebrate forelimb into a wing in a different way


The Great Terminal Mesozoic Extinction

Complete extinction of ammonoids, belemnites, rudist bivalves, dinosaurs, pterosaurs, ichthyosaurs, plesiosaurs, and mosasaurs; big losses among other groups also

The asteroid impact hypothesis of Alvarez (1980), or the return of catastrophism!

Evidence of impact: iridium layer worldwide at K‑T boundary, shocked quartz, microtectites

The possibility of periodic mass extinction: galactic cycle, planet X, Nemesis

Lingering questions: Was extinction gradual or sudden, the cause earth‑based or extraterrestrial?

Chapter 15 – Cenozoic Events


Cenozoic epochs named by Lyell for percentage of modern marine genera

Tertiary/Quaternary remnants from earliest subdivision; Paleogene/Neogene an alternate scheme


Gradual regression of sea, inland seaway gone, Gulf Coast striped with K to Q age sediments

Active tectonics: continents continue spreading, several north‑south collisions occur


Orogenies Forming Modern Rocky Mountains

Nevadan (Jurassic of California): mostly emplacement of granitic plutons, metamorphism

Sevier (Cretaceous of Utah to Alberta): overthrusting and shortening of crust

Laramide (Tertiary of Arizona to South Dakota): vertical domal uplifts like Black Hills

Basin and Range rifting (Miocene to Recent of California to Colorado): normal faulting, basalt


Rocky Mountains are a rare case of inter‑plate mountain building and vulcanism

Cause may have been plate reconfiguration on California coast & subduction of oceanic rift

San Andreas Fault (strike‑slip fault, Baja to San Francisco) also developed as a result


Tertiary lakes formed in intermontane basins (Cannonball Sea, Green River Lake)

Tertiary terrestrial sediments of western U.S. are famous for spectacular scenery and fossils

         Badlands National Park a classic example

Giant volcanic ash falls covered the western United States during the Oligocene and Miocene


Colorado Plateau a raised but undeformed region between Basin and Range Faults

         Grand Canyon bounded by Laramide fold on east, B & R normal faults on west

Great Basin (Nevada and surrounding areas) a large area of north‑south normal faults

Columbia Plateau and Snake River Plain covered by thick Basalt Flows

Active vulcanism continues in Cascade Mountains (northern California to Washington state)


The Closing of the Tethys Sea

Alps and Pyrenees were formed when microcontinents fused to southern Europe

Later Africa sutured to Eurasia forming the Mediterranean Sea, which dried up in Miocene

Rifting has opened the Red Sea and made Arabia (of Gondwanaland) part of Eurasia

India (of Gondwanaland) smashed into Asia beginning in the Eocene to form the Himalayas

The Isthmus of Panama formed to connect North and South America in the Pliocene


Glaciation began in the Miocene on Antarctica as it reached the South Pole.

Glaciation increased in the Pliocene but expanded dramatically in the Pleistocene.

The Pleistocene Epoch is named for the great Ice Age in North America and Eurasia.

Originally four glacial intervals were recognized: Nebraskan, Kansan, Illinoian, Wisconsinan.

It is now known that there were dozens of glacial intervals with interglacials between them.


Effects of the Ice Age

Cycles of glaciation, separated by interglacials, modified the higher latitudes.

Laurentide and Cordilleran Ice Sheets covered Canada in the east and west, respectively.

Tillites cover northern North America and central Europe, loess surrounds drainages.

Sea level dropped during glacials, making the Bering Strait a wide land bridge.

River systems were deranged, Mississippi drainage expanded, Great Lakes formed.

Valley glaciers formed as far south as Mexico at high elevations.

Pluvial lakes formed in Great Basin (Great Salt Lake a remnant of Lake Bonneville).

Plant zones were driven far south of their current ranges then returned north again.


Coastal Zones of the United States effected by Glaciation (from north to south)

Glacial Erosion‑‑many fjords and islands with hard bedrock (coast of Maine, Canada, Alaska)

Glacial Deposition‑‑peninsulas and islands made of glacial till (Cape Cod, Long Island)

Estuaries‑‑drowned river valleys cut by glacial runoff (Chesapeake Bay, Delaware Bay)

Barrier islands & lagoons‑‑stable coasts south of glacially‑effected areas (Carolinas, Florida)


Possible Causes of the Ice Age

Long‑term global cooling may have occurred due to changes in continental positions that altered the flow of ocean currents (oceans now connected only around the south pole).

Individual Ice Ages may be controlled by Milankovitch Cycles or by natural glacial cycles.

The earth's reflectivity (albedo) may have been a positive feedback for formation of glaciers.

Cold high pressure centers and inundation by sea water may have been negative feedbacks.

The Holocene may be only an interglacial stage!


The Ice Age and Life

The Ice Age was a cool and wet time, and plant and animal life was abundant and diverse.

Extinction of giants at end of Pleistocene in North America: mammoths, mastodons, ground sloths, horses, camels, giant lions, saber‑tooth cats, dire wolves, short‑faced bears, etc.

Climatic change and human hunting are competing theoretical causes of the extinction.

Chapter 16 – Life of the Cenozoic


Marine invertebrates (except ammonoids) and protozoans continue much as in the Mesozoic.

Angiosperms (flowering plants) dominate flora; origin of grasses and grasslands in Miocene

Insects diversify together with angiosperms in symbiotic relationships.

Rodents, songbirds, frogs, and bats diversify as seed and insect eaters.

Carnivorous mammals, birds, and snakes diversify as predators of rodents, frogs, and songbirds.

Endothermic mammals and birds are the great success stories of the Cenozoic.



Birds originated in the Jurassic from thecodonts or theropod dinosaurs, Archaeopteryx

Birds became the most successful and diverse group of flyers ever, especially song birds.

Birds became successful predators of fish, shellfish, reptiles & mammals; Penguins fly in water.

Ratites are flightless herbivorous birds; Diatryma was a giant Eocene carnivorous bird.

The fossil record of birds is poor because of their thin bones and lack of teeth.



Mammals originated from synapsid (mammal‑like) reptiles in the Triassic Period.

Mammals remained small & nocturnal during the Mesozoic, diversified after the dinosaurs died.

Mammals have one lower jaw bone, three middle ear bones, and precise tooth occlusion.

Mammal fossils are scarce in the Mesozoic but very plentiful in the Cenozoic.

Multituberculates were rodent‑like mammals with a huge tooth that survived into the Oligocene.

Monotremes (platypus & echidna) are living egg‑laying mammals of the Australia region.

Eupantotheres gave rise to marsupial (pouched) and placental mammals in the Cretaceous.

Marsupials originated in North America, migrated to South America, Antarctica, Australia.

         They thrived in South America until the Isthmus of Panama formed in the Pliocene.

         The opossum was the only marsupial successful at invading North America.

         Australian marsupials are now threatened by competition with invading placentals.

Placentals originated in Eurasia and invaded North America and Africa in the Late Cretaceous.

         Edentates (sloths, anteaters, armadillos) made it to South America from North America.

         Caviamorph rodents & monkeys somehow got to South America from Africa (Oligocene).

Mammals are excellent evolutionary examples of variations on a theme.

         Shrews are the most similar to the original placental mammals of the Cretaceous.

         Bats are similar to shrews except for the elongate fingers with a flying membrane.

         Rodents retain a primitive skeleton but undergo huge variations in tooth morphology.

         Primates remain primitive except for grasping digits and an enlarged brain.

         Creodonts and carnivores elongate the feet and develop shearing teeth.

         Whales loose the pelvic girdle and develop a horizontal fluke for swimming.

         Artiodactyls (camels, deer, cattle) walk high on two toes, have high crescent‑shaped teeth

         Perissodactyls (horses, rhinos) walk high on three or one toe(s), have high‑crowned teeth.

         Proboscidians (elephants, mastodons) have pillar‑like limbs, sequential tooth eruption.

The earliest large mammals (titanotheres, giant rhinos) went extinct; iterative evolution


The Ice Age was a cool and wet time, and plant and animal life was abundant and diverse.

Extinction of giants at end of Pleistocene in North America: mammoths, mastodons, ground sloths, horses, camels, giant lions, saber‑tooth cats, dire wolves, short‑faced bears, etc.

Climatic change and human hunting are competing theoretical causes of the extinction.

Chapter 17 – Human Origins


Order Primates

         Suborder Prosimii

                  Superfamily Tupaioidea (tree shrews)

                  Superfamily Lemuroidea (lemurs)

                  Superfamily Lorisoidea (bush babies)

                  Superfamily Tarsioidea (tarsiers)

         Suborder Anthropoidea

                  Superfamily Ceboidea (South American monkeys, prehensile tail)

                  Superfamily Cercopithecoidea (African Monkeys)

                  Superfamily Hominoidea

                           Family Hylobatidae (gibbons, siamangs)

                           Family Pongidae (orangutans, chimps, gorillas)

                           Family Hominidae (humans)


Primate specializations include shortened face, forward‑facing eyes, enlarged brain, long limbs, and grasping hand with opposable thumb.  Otherwise primates are unspecialized.

Early primate adaptations are attributable to living in trees and catching insects by hand.


Earliest primate Purgatorius from Cretaceous Hell Creek Formation of Montana

Prosimians diversified in North America and Eurasia during the early Cenozoic

Cooling temperatures reduced their range to southern Asia and Africa

Monkeys reached South America from Africa by an unknown route in the Oligocene.

Apes arose in the Miocene of Africa as grasslands developed there, have 5‑cusp molars.


Early Miocene: Dryomorphs (large canines, Africa to Eurasia)

Middle Miocene: Ramapithecines (small canines, very diverse)

Late Miocene/Early Pliocene: poor fossil record


It was long believed that Ramapithecus was the first human and that the human/ape split occurred at least 15 M.Y. ago.  DNA and protein similarities, however, suggested a mere 5 M.Y. ago split with man, chimp, and gorilla being equally similar.  Discovery of more skeletal material revealed that Ramapithecus is an orangutan.  Earliest fossil humans are middle Pliocene


Hominid species                      Age                   Brain size          Height

Australopithecus afarensis    4.0‑3.0 M.Y.     380‑450 cc      1.2 m   ("Lucy," fully bipedal)

Australopithecus africanus    3.0‑2.5 M.Y.     380‑450 cc      1.4 m

Australopithecus robustus     1.9‑1.6 M.Y.     380‑450 cc      1.5 m

Australopithecus boisei         2.2‑1.2 M.Y.     380‑450 cc      1.5 m

Homo habilis                         2.0‑1.6 M.Y.     650‑800 cc      1.2 m

Homo erectus                        1.6‑0.3 M.Y.     800‑1300 cc    1.7 m

Homo sapiens                        0.1‑0.0 M.Y.     1000‑2000 cc  1.8 m

         Neanderthal Man (replaced Homo erectus, large brow ridges, elaborate burials)

         Cro‑Magnon Man (replaced Neanderthal 40,000 B.P., made cave art in France & Spain)

         Modern Man (developed from earlier forms, domesticated plants & animals)


All human species appear to have evolved in Africa.  The Piltdown Man hoax of England (1912‑1953) was believed because it fit the expectation of finding human fossils in Europe.


Human evolution is a case of neoteny (retention of juvenile characters: large head, sparse hair).


Human evolution was an Ice Age phenomenon and has been linked with the simultaneous appearance of many "grotesque giants" among the northern mammals (Irish elk, polar bear, etc.)

ESCI 103 ‑‑ Review sheet for final exam


Know important contributions of the following scientists:

Louis Alvarez               Lord Kelvin                  Adolph Seilacher          Charles Walcott

Charles Darwin             Charles Lyell                William Smith               Alfred Wegener


Know the age, plate boundary type, and continents involved in the formation of the following mountain ranges:



Appalachians (3 Paleozoic orogenies)


Rockies (4 Mesozoic/Cenozoic orogenies)



Know era of origin and peak diversity for the following:

Prokaryotes (bacteria and cyanobacteria [including stromatolites])

Eukaryotes (single celled and multicellular)

Ediacara Fauna (know significance and reason for preservation)

Burgess Shale Fauna (know significance and reason for preservation)



Fishes (ostracoderms, placoderms, acanthodians, cartilaginous fishes, bony fishes)


         Ancestral (large) forms



         Dinosaurs, pterosaurs, marine reptiles





         Carnivorous giants

         Song birds


         Whales, bats, odd‑toed ungulates, even‑toed ungulates, proboscidians, rodents



Know prominent fossils (including reef formers, good index fossils, and top carnivores) of the following time periods:








Have a full grasp of the important aspects of the following topics:

Uniformitarianism, composition of atmosphere, history of solar system and earth, relative and absolute dating, geologic time scale, organic evolution, plate tectonics, glaciation events