Like most of Oregon and Washington south of Puget Sound into the Willamette Valley the landscape and climate of Clark County are determined by its placement between the volcanic Pacific Coast and Cascade Ranges, where glaciation helped form a U-shaped valley which meets the river valley of the Columbia River as it leaves the Columbia River Gorge. Volcanic andisol soils are common, with fertile mollisols in the lower areas. The central and southwest areas of the county are generally flat floodplains, sculpted by torrents of prehistoric Lake Missoula. A series of dramatic floods known as the Missoula Floods took place 15,000 – 13,000 years ago, as several ice dams melted, forming a series of low steps such as the “Heights”, “Mill Plain”, “Fourth Plain” and “Fifth Plain”. Clark County’s Köppen climate classification is “Csb.” (From Wikipedia on Clark County)

Counties: Cowlitz, Clark, Lewis, Pacific, Skamania, Wahkiakum County

Features: Termination of the Columbia River, Cape Disappointment, Long Beach Peninsula, Mount Saint Helens,