Caves and Karst in Southeast Alaska

Forest soils can be very acidic in the cool Alaskan rainforest. As a result, karst features form wherever limestone or marble bedrock is present. Nearly all the drainage in these areas is underground, and sinkholes and caves are common. In the photo to the right, a river emerges from Cavern Lake Cave on northern Prince of Wales Island. The water originates from Cavern Lake on the hillside above. This cave is one of two that Tongass National Forest has designated for visitors (the other being El Capitan Cave), and a trail and viewing area have been constructed. No gate has been placed on this cave because it only extends back about 50 meters (and requires wading for most of that distance). So it is safe for visitors and provides a clear example of drainage in a karst system.

Because the geology of Southeast Alaska is so complex (resulting from oblique microcontinent collisions), limestone is scattered about the region in a seemingly random pattern. But wherever limestone is present, caves can be found in abundance. These vary from large to small, with passages that are horizontal or vertical, and with entrances that range from gigantic sinkholes to tiny, obscure openings. Caves with active rivers tend not to preserve fossils because of the frequent flushing, although some such caves (El Capitan and Devil's Canopy) contain fossils in upper levels where conditions are quiet.

Starlight Cave (left, right, and below) is one of the larger and more spectacular pits on Prince of Wales Island. It is an effective natural trap for deer. At the bottom, a horizontal cave extends in two directions.

Two types of caves in Southeast Alaska contain fossil bones: 1) carnivore dens and 2) natural traps. Carnivore dens tend to be small horizontal caves, generally 1-2 meters in height and width and about 30 meters long. They also tend to have tight entrances. Most of the caves listed below fit this pattern. Bears, otters, and (in the past) foxes have used such dens, which contain their own remains plus that of their prey (primarily rodents, birds, and fish). Natural traps are pit caves into which large mammals occasionally fall (especially bears and deer). Although these caves tend to have lower diversity than den sites, they help to fill in the record for large herbivores which are underrepresented in the den sites. Zina Cave and Hole 52 Cave are examples of natural traps in Southeast Alaska from which fossil mammal skeletons have been recovered. Many others have been identified that contain only recent deer remains (see photos of Starlight Cave at left and above).

Below are links to cave sites that have been excavated or investigated as part of the paleontological research in Southeast Alaska. The amount of work done at each site, as well as the potential for future excavation, varies greatly and will be discussed individually for each cave. Work in some caves is completed, whereas others are prime targets for future excavations. The sites are listed by region and in the order in which they were found or excavated.

   
© 2002 by Timothy H. Heaton