CRITERIA FOR RECOGNITION OF LAHARIC BRECCIAS, SOUTHERN CASCADE MOUNTAINS, WASHINGTON
Comparison of properties of laharic (volcanic mudflow) and pyroclastic breccias leads to the conclusion that two described volcanic breccias near Mt. Rainier, Washington originated as lahars. The two volcanic-breccia deposits are typical of many breccias within a thick andesitic series (Eocene-Oligocene), suggesting that rapid denudation of nearby volcanoes was an important process in the accumulation of the lower Tertiary andesitic material within the southern Cascade Mountains of Washington.