Only the Clear Lake volcanics in California lie as far west in the coterminous United States. Below this they were scoured by the cataclysmic Bretz floods from Glacial Lake Missoula around 13,000 to 15,000 years ago.
Boring lava is characteristically a light-gray phyric olivine basalt.
A specimen from Rocky Butte is predominantly labradorite, with phenocrysts of olivine, mostly altered to iddingsite. The volcanoes locally contain scoria, cinders, tuff, tuff breccia, and ash. Battleground Lake State Park is nestled in a stately stand of timber northeast of Vancouver, Washington. The deep, small, oval-shaped lake is an ideal family angling destination, and is only about 45 minutes from Portland. The park offers camping, hiking, picnicking, swimming, and of course, fishing.