EARTH, WIND AND FIRE: SUBSURFACE PITS AT FORT CLATSOP

Surface indications of Lewis and Clark’s Fort Clatsop near Astoria, Oregon have not been identified by archaeologists, and subsurface evidence for the 1805-1806 occupation has been lacking. Archaeological investigations at the site of the Corps of Discovery’s winter encampment have identified ubiquitous subsurface pit-shaped features dotting the landscape. The origin of these pits has been the subject of much speculation over the past five decades, but archaeologists have often assumed them to be of cultural origin. Some have been identified as hearths while others have been called trash or privy pits. An alternative hypothesis is that the pits can be explained by periodic natural disturbances, such as wind and forest fires. Wind and fire disturbances will create at least two types of features in the substrate. Pits will be created when tree roots are ripped from the ground and filled by forest litter, soil organisms, and fire debris. Near surface concentrations of charcoal, ash and burned mineral substrate will be created and preserved when tree roots are burned in place. Recent detailed analyses of a sample of pit features included a comparative study of stratigraphy, granulometry, organic matter and carbonate percentages, and soil chemistry (P and Hg). This research indicates that the pits at Fort Clatsop can be explained by natural disturbances, which have significantly altered the landscape.