A GEOARCHAEOLOGICAL INVESTIGATION FOR AN 1805 LEWIS AND CLARK SITE, COASTAL OREGON

Lewis and Clark, legendary explorers of the western USA, spent the winter of 1805 along the Oregon coastline. During their stay, they mapped many locations, including a native village along the former Clatsop River. Several wooden structures south of the river's outlet to the Pacific Ocean were noted in their journals. Previous investigations by other researchers have failed to locate the historic site. This research coincides with the Lewis and Clark Bicentennial and seeks to resolve the physical location of the Clatsop native village and associated Clatsop River channel outlet.

After reviewing Lewis and Clark's map and journal records, and speaking with local residents, a study area was selected along the west shore of Slusher Lake, within the Camp Rilea Military Training Facility, near Warrenton, OR. Ground penetrating radar (GPR) equipment (PulseEKKO 100 and 1000 systems) was used to image the subsurface to depths of up to 16 m. An Australian bucket auger and Oakfield soil borer were used to collect 21 cores. A Trimble ProXR differential global positioning system (dGPS) and ArcGIS 8.3 were used to create a spatial database and site map that incorporates the locations of laser level stations, soil cores and descriptions, GPR transects, and surrounding site infrastructure.

GPR profiles collected along the ridge west of Slusher Lake show parallel to sub-parallel, continuous to semi-continuous reflection patterns, which are interpreted as vertically accreting coastal sand dunes. A channel-form reflection pattern was noted on the GPR records northwest of Slusher Lake and is interpreted as the old, relict Clatsop River outlet originally mapped by Lewis and Clark. Core samples collected to a maximum depth of 6 m along the GPR profiles reveal no buried soils or cultural remains. This suggests that the village is located > 6 m below the modern surface. These results have helped constrain the physical location of the historic native village mapped by Lewis and Clark and are being used to plan a detailed subsurface investigation within the Slusher Lake study area. Future work will involve the use of GPR and hydraulic coring equipment to attempt to locate and sample cultural remnants dating to the time of Lewis and Clarks’ arrival.