About Forty Last-Glacial Lake Missoula Jökulhlaups through Southern Washington

Geologic map of the Vancouver and Orchards quadrangles and parts of the Portland and Mount Tabor quadrangles, Clark County, Washington, and Multnomah County, Oregon

“…Historically inactive but position atop cataclysmic-flood deposits requires late Pleistocene or Holocene age. Radiocarbon ages from eolian silt on uplands near Ridgefield, north of map area, show episodic deposition through the Holocene (Punke and others, 2011) Cataclysmic-flood deposits (Pleistocene)-Sediment deposited by colossal glacier-outburst floods caused by repeated breaching of ice dam that impounded Pleistocene Lake Missoula in western Montana (Bretz, 1925(Bretz, , 1959Allison, 1978;Waitt, 1980Waitt, , 1985Hanson and others, 2012). Largest floods achieved stages of 400 ft (120 m) above sea level as they spread over the eastern Portland Basin.…”

Hydrogeologic Model for the Gable Gap Area, Hanford Site

“…Sandy beds may be fine and grade upward into thin beds of sandy silt to silt (see Figures 4.9B and 4.1); graded beds such as these are sometimes referred to as "rhythmites." Each rhythmite may represent the deposition from a separate flood (Waitt 1980(Waitt , 1985Smith 1993), or perhaps surges from a single flood (Bjornstad 1980, Baker et al 1991. Most rhythmites go undetected in boreholes; however, because drill cuttings are generally collected at 5-ft intervals, the scale of the rhythmic bedding is much finer.…”

Hydrogeologic framework, groundwater and surface-water systems, land use, pumpage, and water budget of the Chamokane Creek basin, Stevens County, Washington

“…Glacial Lake Missoula, dammed behind the Purcell Trench lobe ( fig. 4), was about 600 mi 3 in volume and reached a maximum depth of 2,200 ft (Waitt, 1980). Enormous catastrophic floods occurred over a 2,000-year period when the ice dam of the Purcell Trench lobe periodically failed, sending floodwaters west and southwest.…”