FIELD TRIP SIDETRIP K - Twin Lakes Road off Mount Baker Highway (State Route 542)

Twin Lakes Crinoid stem fossils in block of Chilliwack limestone. Ancient volcanic rocks and a glacial pass Twin Lakes are glacial tarns nestled in a U-shaped glacier-carved pass. The brown and rubbly rocks rising up from the evenness of the pass are volcanic rocks of the Chilliwack River terrane, and with a bit of looking, visitors can find fragments or pods of light grey, roughened limestone. Light-colored outcrops on the hillside, which contrast with the darker volcanic rocks, may be the same material. Some of these pods in the volcanic rocks have fossils (see also fieldtrip stop 1). The volcanic rocks themselves are so altered by metamorphism that on close approach they are rather nondescript and unattractive even to a geologist.

On to Lone Jack Mine

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| USGS Geology in the Parks home | NPS Park Geology Tour home | This site is a cooperative endeavor of the US Geological Survey Western Earth Surface Processes Team and the National Park Service. Please share your comments and suggestions with us! parkgeology@den.nps.gov http://www.nature.nps.gov/grd/usgsnps/noca/nocastK.html This page was last updated on 11/30/99

Material in this site has been adapted from a new book, Geology of the North Cascades: A Mountain Mosaic by R. Tabor and R. Haugerud, of the USGS and published by The Mountaineers, Seattle