Harder Road Site. Harder Rd crosses the Cheney-Palouse scabland tract. This roadcut is mentioned in Baker (1973) and other articles on scabland flooding, but nowhere well photographed. Its not a big exposure, but contains an advanced-stage calcrete (>Stage III) developed in an upward-fining deposit of sandy loess over >4m of pre-Missoula flood gravel. What we see at Harder is a remnant of a former landscape, one where this blanket-like calcrete crust (a dryland paleosol) was

Synthetic hydraulic fractures produced in Jell-O using a straw and colored syrup (left) and a natural one in the Touchet Beds (right) as sketched by R.L. Lupher (1944). It doesn't take a huge force to generate hydraulic fractures. The conditions just have to be right. A disc-shaped, sand- and gravel-filled intrusion is fed from above by a slender conduit. This structure in the Touchet Beds (Missoula flood deposits) appears identical to hydraulic fractures produced with a stra

The tops of clastic dikes in the megaflood region appear five ways. 1.) Truncated at a bedding contact or an erosional surface 2.) Fracture and fill 3.) Fade out, possibly by bioturbation 4.) Sag becomes dike 5.) False upward pinchout Fracture and fill. Bedforms become infill. The quarter is located at a bedding contact between two flood rhythmites. A fracture opened in the top of the lower bed and filled with sediment. The sand was not vented upward from some layer below. Se

Clastic Dikes in Basalt Bedrock Sheeted dikes with sandy fills intrude downward into Miocene Columbia River Basalt in the Walla Walla Valley, Pasco Basin, Umatilla Basin, Lewiston Basin, and Yakima Valley of Washington, Oregon, and Idah. These same dikes intrude Neogene basin-fill deposits and Pleistocene sediments that predate Missoula Floods (pre-Late Wisconsin, >28 ka). The sheeted, per descendum dikes were not produced by liquefaction. Rather they are injectites (Cooley,

Lateral spreads. A network of lateral spread fractures in pavement formed by an earthquake. Peru 1970. USGS photo archive. Lateral Spreading: A proposed origin for sheeted clastic dikes in Eastern Washington Earthquake-triggered lateral spreading is invoked to explain the many thousands of sheeted Pleistocene clastic dikes in south-central Washington (Cooley et al., 1996; Neill et al., 1997; Pogue, 1998). Previous articles have not provided a coherent model, but I imagine the

What Does Periglacial Mean? "Periglacial" is a term that packs a punch. Like "tundra" or "permafrost", it stands in for a full suite of cold-climate features, biophysical processes, and conditions. Periglacial regions are those that lie just beyond areas covered by glacial ice. They are swaths of cold-affected ground that often fringe glaciated terrain where Mean Annual Temperature (MAT) ranges between -2 to -5 degC. Frozen ground is the common to all periglacial environments

Upward tapering clastic dikes are very rare in the Touchet Beds and other Pleistocene-age deposits in the Channeled Scabland. Nearly all clastic dikes in the region are wedge-shaped and filled from above (Jenkins, 1925; Lupher, 1944; Black, 1979; Woodward-Clyde, 1981; Pogue, 1998; Cooley, 2020). One in one thousand is a reasonable estimate of the upward to downward ratio. Nevertheless, the literature - especially Hanford Site reports - contains a long history of misinterpreta

Reconnaissance Geologists of the Columbia Basin & Okanogan Highlands A significant number of geologists visited Eastern Washington prior to J Harlen Bretz. Their observations on aspects of the region's landscape including glacial deposits, ore deposits, basalt stratigraphy, the Grand Coulee, White Bluffs, and many others informed Bretz's work. O.P. Jenkins with binoculars and an assistant at White Bluffs, WA in 1921. WGS photo archive. J Harlen Bretz (1882-1981) is a colossus

Recent faulting and interesting Plio-Pleistocene stratigraphy exposed in shoreline bluffs along Lower Crab Creek are worth checking out. While the the geography can be a bit confusing, its an easy place to access. The hiking is moderate, mostly off-trail, though some brush and loose footing will be encountered. Total roundtrip hiking distance is less than two miles no matter where you park and turn around points are everwhere. That said, any excusion into Lind Coulee will inc