Northrup Canyon is a glaciated coulee east of Steamboat Rock
along Highway 155. This image shows a grass filled valley that was likely
once a glacial lake. The high cliffs in the distance are Columbia River
Basalt. The conifer forest grows amongst outcrops of glacier carved granite.
The glaciers carved roche moutonnees in the granite. A roche moutonnee
is a small bedrock hill that typically is rounded by glacial erosion on
the uphill side, but has steep cliffs on the downhill side caused by the
moving ice sheet plucking away blocks of bedrock. The orientation of roche
mountonnees can indicate the direction of ice movement. In many places,
the surface of the granite still preserves striations (scrape marks left
by rocks dragging along in the bottom of the ice sheet). |