Deep-sea sedimentary record of the late Wisconsin cataclysmic floods from the Columbia River

New results from Ocean Drilling Program Site 1037 and U.S. Geological Surve y high-resolution seismic-reflection profiles confirm the great thickness, fast deposition rate, distant source, and convolute path of turbidites that fill the Escanaba Trough, the rift valley of the southernmost segment of t he Gorda Ridge. Accelerator mass spectrometry C-14 measurements provide the first direct dating of the Escanaba Trough turbidites, demonstrating an av erage deposition rate faster than 10 m/k.y. between 32 and 11 ka and as fas t as 15 m/k.y. during the oxygen isotope stage 2 lowstand, In the upper 60 m of sediment, the petrology of turbidite sand beds, which are as much as 1 2 m thick, show that the dominant source for the turbidites is from the Col umbia River, which is more than 800 km to the north, rather than from the m uch closer rivers of northern California. New high-resolution seismic-refle ction profiles show that, except for areas of very recent volcanism, the en tire Escanaba Trough below 3200 m water depth is floored by the turbidite s equence that was cored in the upper 60 m at Site 1037B, The ages of the upp er 120 m of turbidites correspond with the ages of channeled scabland depos its associated with latest Quaternary jokulhlaups from glacial Lake Missoul a, The age and source characteristics suggest that these megaturbidite beds in Escanaba Trough are most likely deposits formed by hyperpycnally genera ted turbidity currents as the largest of the Lake Missoula floods entered t he sea.