A long (55 miles) ridge which runs from the Cascade Mountains to the Columbia River
and is part of the Columbia River Basalt flows from 17 to 14 million years ago.
It's plant community is defined as part of the shrub-steppe zone.

Shrub-steppe is defined as that area dominated by grasses and brush (~sagebrush) with
low rainfall and variable soils. In North America it covers that area between the
Cascades/ Sierra Nevadas to the Rocky Moutains from SE British Columbia down to
Arizona and New Mexico. Within this large area (~200,000 square miles) there are
many sub-divisions.

The wildflowers shown here represent the Standard and Lithosol Vegetation Zones as
defined by R. Taylor in "Sagebrush Country", 1994.