Lahar Stratigraphy - S Fork Toutle River
Gardner State Park has excellent exposures of lahars from the 1980 eruption as well as several older events. Look for the transition from rock-fragment dominated to pumice-dominated flows in the younger material in the low cut along the roadway. The hillside above has a much older deposit.
Photo by James Maynard © 2009 - free use with attribution
A layer of asphalt pavement provides a reference surface separating older and younger lahars.
Photo by James Maynard © 2009 - free use with attribution
