Geology of the Okanogan Highlands 2011 - Stop 7


Ralph Dawes compares his geologic map with what is found on the ground.


Dacite, from lava flow.


Cheryl Dawes takes a closer look to determine the composition of the elongated black marks in the dacite, and suggests they may be obsidian.   

Suggested resources:

    •Northwest Exposures -- a Geologic Story of the Northwest,
     by David Alt and Donald Hyndman

    •Roadside Geology of Washington,
     also by David Alt and Donald Hyndman, Mountain Press Publishing (Missoula, Montana).  ISBN            number 078-0-87842-160-2

    •Note: The Roadside Geology series of books also includes other states that may be of interest.