Geologic units in Washington (state in United States)
Darkgray, finegrained, dense, porphyritic in part, basalt flows in central and southcentral part of State; commonly interbedded with conglomerate, sandstone, and siltstone. Includes small areas of rhyolite north of Cle Elum in Kittitas County, and andesite north of Leavenworth in Chelan County.