Lawyers Cave

On the Alaskan mainland east of Wrangell Island, along Blake Passage, a thin band of marble extends up the mountainside. In this carbonate rock, several caves and many other karst features have been located by Forest Service scientists and cavers of the Tongass Cave Project. Lawyer's Cave is the closest of these to the ocean and was discovered and named by local residents. Cavers, not aware of the previous name, called it Phalanges Phreatic Tube--"phreatic tube" for the cave's shape and origin, and "phalanges" for the toe bones of a bear that they found inside.

The cave has two entrances: an abrupt tubular opening on the north end and a small sinkhole on the south end. The cave is 20 meters long and is a non-branching horizontal crawlway from end to end (see photo below). The floor sediment is soft and organic on the southern end and more rocky and inorganic in the middle and at the northern end. Bones of bears, birds, and fish were found scattered about on the surface in the rocky areas.

Dr. Heaton visited Lawyer's Cave with Jackie de Montigny of Tongass National Forest (Wrangell District) and USD students Andy Klock and Nat Carter for two days in 1998. In the initial exploration of the cave, Dr. Heaton found a bone awl at the surface inside the south entrance (see photo below). They mapped the cave and collected a sample of bones. They also dug four shallow test pits and took sediment samples from two other surface locations for screening. The sediments contained abundant rodent and fish remains, plus two obsidian flakes were found (one shown in photo below). The three artifacts were turned over to archaeologist E. James Dixon for study.

The artifact and two other bone samples were submitted for radiocarbon dating to get general idea of the age of the deposit. A bear phalanx found on the surface was dated to 6,290 years old, and a duck coracoid buried 20 cm (at the bottom of the deepest test pit) was dated to 8,880 years old. The bone awl was dated to 3,050 years old. The fact that an early Holocene date was obtained from a shallow test pit means that the cave holds great promise for elucidating the early postglacial history of the Alaskan mainland.

The most surprising discovery of the cave, compared to the fossil sites on Prince of Wales Island, was the diverse rodent population. From a mere 16 bags of screened sediment, five rodent species were recovered: flying squirrel (Glaucomys), deer mouse (Peromyscus), long-tailed vole (Microtus longicaudus), red-backed vole (Clethrionomys), and bog lemming (Synaptomys). Each species was represented by 2-7 isolated teeth. This diversity seemed remarkable compared to the extensively-excavated postglacial den sites such as El Capitan and Bumper Caves, which produced only one to three species of rodent. The reason for this difference can be found by considering modern populations. Because of the water barrier that separates the mainland from the coastal islands, the islands have only a small subset of the terrestrial micromammals. The question to be asked is how long these rodent species have been present on the mainland, and therefore how long they have had to attempt island colonization.

Lawyer's Cave clearly holds great potential for elucidating the early postglacial history of Southeast Alaska. Because of this, a larger excavation is being planned.

   
© 2002 by Timothy H. Heaton