During a visit to the Boisfort Valley I noted this isolated small hill rising from the floor of the valley. I had no time to visit the hill, but noted it is the site of a cemetery.
Small hill in the Boistfort Valley
Same Boisfort hill from the southwest
The Boistfort Valley is located in the east Willapa Hills. The Boisfort Valley is one of the earliest Euro/American settlement areas in Washington State with some of the earliest donation land claims as well as the oldest public school district in the state. The name Boistfort is old French meaning strong wood and was likely named by early Hudson Bay Company French fur employees that settled in the valley. The valley was along the route from Fort Vancouver on the lower Columbia River to Fort Nisqually on Puget Sound. Topographic maps show it as Boistfort Prairie. Green forested hills rise up to the east and west. The valley was badly flooded in 2007 during heavy rains and hundreds of landslides on the steep forest lands above the valley. The South Fork of the Chehalis River flows from south to north through the valley. The valley had decidedly northern California feel about during my visit - hot 90s plus temperatures, brown grass and large oaks on the valley floor.
Wells (1981) and Wells and Sawlan (2014) geology maps of the east Willapa Hills have the hill mapped as part of the younger alluvial material that covers the valley floor, but its elevated stature suggests it is an older erosional remnant. Perhaps too small of a scale to warrant a separate designation. Wells mapped a nearby similar height ridge as a basaltic intrusion and the lower slopes of the valley as McIntosh marine sediments. So possibly the hill is an older alluvium deposit remnant or some harder outcropping of bedrock rising slightly above the valley floor.
Even more intriguing is the Lewis County soil map. That map indicates the hill is underlain by Salkum silty clay loam, a soil derived from glacial drift. The glacial drift interpretation would be exciting (for glacial history folks) as it is well south of the interpretation of the farthest extent of the Puget ice lobes. There is a mound-like hill of somewhat slightly greater height north of Chehalis call Grand Mound that is mapped on geology maps as glacial drift of uncertain age. Perhaps the soil mappers were influenced by the mound topography at Grand Mound and based the interpretation off of that mound. But then again it is hard to figure how this little bump is glacier related given its location.
A land form worth some further investigation perhaps.