ANCIENT CATACLYSMIC FLOODS IN THE PACIFIC NORTHWEST: ANCESTORS TO THE MISSOULA FLOODS

The Missoula Floods left erosional and depositional features behind in eastern Washington, now termed the scablands. At least 89 floods occurred when Glacial Lake Missoula’s ice dam repeatedly ruptured and re-formed between 15 to 18 thousand years ago, with 40 of the floods reaching Wallula Gap (Allen et al., 2009). Evidence of older deposits have been wiped out by the Missoula Floods in most places. By searching geological literature evidence of older flood deposits can be found. Geologists have sited magnetic reversals in flood sediments that date some paleosols to at least 780,000 years before present. Further evidence can be found in the formation of caliche, which takes longer than 15,000 years to form. This project will involve visiting every site referenced in literature to look for evidence of older flood deposits. Each site will be described and samples will be taken and analyzed for color, particle size, cementing, caliche, and dates where possible. Flood deposits from the sites will be correlated to each other to begin to form a chronology of the Ancient Cataclysmic Floods.