ALTOONA AREA ROADCUTS
Whakiakum County, Washington, USA

GEOLOGY
Upper Tertiary Basalt - Basalt of Altoona - Miocene to Pliocene age basalt of "Atoona type" are exposed east of Altoona and consist predominately of flow breccia with small amounts of pillow lava and massive basalt. Although temporally and petrographically similar to the Columbia River Group of the Columbia Plateau to the east, the abundance of related intrusive rocks in the Grays River area and no evidence for physical connection to the Columbia river basalt flows suggests that the Altoona type basalts are locally derived and proximal to their eruptive center (Wolfe & McKee, 1972).

MINERALS
*Quartz-
SiO2- Occurs as curved mm-scale crystals.

* photographed

 
Curved QUARTZ




REFERENCES

Wolfe, Edward W., McKee, Edwin H., 1972, Sedimentary and Igneous Rocks of the Grays Harbor Quadrangle, Washington,
     State of Washington Geological Survey Bulletin 1335, 70 pages.