Intrusive basalt and andesite

Sills, plugs and dikes of basaltic andesite, basalt, and andesite. In the Cascade Range most of these represent feeders, exposed by erosion, for flows and flow breccias of units Tba and Trb and a few are feeders for units QTba and QTa; in foothills of western Cascades includes several sins and dikes that may represent feeders for flows in unit Tu. May include some invasive flows. Includes a few dikes of hornblende and plagioclase porphyritic andesite, commonly altered, that probably were feeders for parts of unit Tu
State Oregon
Name Intrusive basalt and andesite
Geologic age Miocene to Pleistocene
Lithologic constituents
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-andesite (Dike or sill, Stock or pipe)
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basalt (Dike or sill, Stock or pipe)
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basaltic-andesite (Dike or sill, Stock or pipe)

Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.

NGMDB product
Counties Clackamas - Klamath