Defining Paleo-Thorne Lake
Tongass National Forest, Alaska, 2004
by Terry Fifield, FS Archaeologist
The concept behind the Defining Paleo-Thorne Lake project in the Thorne Bay Ranger District was to combine an idyllic paddle up the Thorne River, the largest drainage on southeast Alaska’s Prince of Wales Island (POW), with a geologic search for the shoreline of an intertidal lake thought to exist on the lower Thorne River in the early Holocene period, 7,500–10,000 years ago. Recent archaeological and paleontological research on POW had brought to light one of the earliest human occupations on the Northwest Coast (10,700 B.P.) at On Your Knees Cave as well as the remains of brown and black bear, marmot, heather vole, arctic fox, and other animals that lived during the last ice age. This research, coupled with palynological (pollen) coring of lake-bottom sediments and bogs by Tom Ager of the U.S. Geological Survey, had led Tongass NF Geologist Jim Baichtal to suspect that a substantial salt lake had once existed 6–10 miles inland of the current mouth of the Thorne River. Our long-term goal is to reconstruct the shoreline of the salt lake and identify where people of the early Holocene might have camped. We intended to search for marine shell beds preserved in the estuarine muds forming the modern riverbed and to core bogs and pond basins on tributary drainages.
The reality of the PIT project was perhaps not what the participants imagined when they signed on. We had timed the trip for the late spring, hoping to catch the river at a moderate rate of flow, permitting us to paddle most of the 9 miles of the trip. But it was a beautiful, sunny spring in southeast Alaska, and when May 17 arrived, the river level was very low. We put our four canoes in the water at the Goose Creek confluence with the Thorne, in the middle of a shallow, boulder-strewn section of the river. The crew’s introduction to the project was to slip and stumble over slimy, bowling-ball-sized rocks, while towing canoes loaded with a week’s camping supplies, first downstream and then back up a mile or so to our evening campsite. The river corridor was beautiful, and we did spot some promising shell exposures in the stream banks. Nonetheless, enthusiasm for the “paddle” was not high at the end of day one. Our feet were sore!
As the week progressed, the paddle and the weather improved. We moved into sections of the river corridor where long quiet pools were interspersed with shallow riffles and gravel bars. Sitka blacktail deer grazed on the riverbanks, and there was almost always a bald eagle or two watching from the towering canopy of the old growth spruce and hemlock forest. In the hot sun, we collected marine shell samples from the riverbed and augured beneath the river bottom to a depth of over 2 m, collecting evidence of the past marine and estuarine environments. In two basins adjacent to the Thorne, the team, straining their backs and arms, used the auger with maximum extensions to collect what appears to be glacio-marine muds from infilling basins between 3 and 4½ m below bog surfaces. And on a final day of exploring, we paddled and dragged our canoes about 2 ¾ miles upstream to visit a historical-period trapper’s cabin associated with a modern canoe route.
Though perhaps not the serene paddle envisioned by all the volunteers, the trip was a success. We enjoyed each other’s company and the exertions of the work in the wildness of the river corridor. We collected some valuable data that will extend our understanding of the post–ice age environment of POW. And, on the last day, we floated 9 miles downstream, bumping and bouncing over the boulder fields, quietly floated through the deep pools soaking in the dark reflections of the forest, and even enjoyed a little fast water in the incised sections of the lower river. We felt the tide try to push us back into the forest as we paddled out of the modern estuary and into the community of Thorne Bay. It was a rewarding, if a bit exhausting, trip.