We have a singular focus: Collect accurate fill band counts from several hundred locations along the 500 km-long flood route through the Columbia Basin (Lewiston, ID to Albany, OR). We have planned our stops in advance and secured the necessary landowner permissions in order to maximize travel efficiency.

The funding we seek directly supports field data collection, including the travel and spartan accommodations (tent camping).

Our study area is vast. Getting to all of our sample sites is our primary challenge. We provide our own excavation tools, sample-collection supplies, camping equipment, and vehicles so no new equipment will be purchased.

This is bare-bones, old-school field work like you probably did back in the day.

Additional Information

A typical clastic dike in Missoula flood deposits. Each vertical fill band represents an increment of filling and dike widening driven by flood loading. Each band represents one outburst flood event.Some dikes grew very large. This one is 2m wide. Many show evidence of reinjection over time, consistent with the 2000-3000 year Missoula flood cycle. The left-most fill band in the photo above intrudes from the bed just above and left of the trowel. On the right, many fill bands intruded later and were sourced in the overlying beds. One way we can tell the dikes intruded downward from the surface is by the composition of their fill. Whatever sediment was available at the surface at the time of injection was forced downward. In this case, light-colored silty sediment was injected into ancient river gravels.Once in awhile you get lucky and catch the dikes in the process of formation. These examples show how mobilized sediment cuts across sedimentary layering, but was only able to reach this stratigraphic level.If you excavate away the sandy fill material to expose a dike's wall, you will see this. The silt walls are lined by upward-pointing features called "flute casts". Flute casts are unambiguous indicators of fluid flow direction. Sediment entered the dikes from above.The dikes have clear relationships to flooding. Here, downward-tapering dikes originate from the base of a high-energy backflood channel confined in a narrow bedrock canyon.The dikes cut straight through layers of varying grainsize and strength routinely. This dike, thicker at its top, originates in tan colored flood sediments at the top of the outcrop and penetrates downward through older layers of sand, silt, and gravel.Reinjection of younger fill bands into older ones is common. Here, a smaller dike (right) joins a larger one (left), utilizing the pre-existing plane of weakness.In several locations around the Columbia Basin, silt-sand dikes intrude bedrock. This example shows a 15cm-wide dike intruding several meters into pillow basalts of the Columbia River Basalt Group. The dike is sourced in flood sediment atop deposited atop the basalt (out of frame). Cross-cutting relationships like this leave little room for traditional explanations that attribute the dikes to liquefaction and upward escape of fluidized sediment. Clastic dikes in the Columbia Basin are unusual in the geologic record. Fieldbook for scale.Floodwater loading appears to explain best the large soft-sediment deformation features preserved in shoreline exposures near the mouth of the Sanpoil River. The Sanpoil is located 200km north of Wallula Gap and the major through-going fault zone, the OWL. Here, clay-rich sediment of Glacial Lake Columbia was mobilized by Missoula floods that overtopped them, forming a contorted, dike-like body.One way to visualize the formation of clastic dikes by floodwater loading is with this debris flow analog from Black Dragon Canyon, Utah. The photo shows red clastic dikes forced downward into light-colored sediment from the base of a heavy, over-riding debris flow. Debris flows are rapidly-deposited and can be quite voluminous, thus impose heavy loads. Missoula floods also arrived very quickly and were, in places, more than 100m deep. Slackwater lakes in back-flooded valleys stood atop valley fill sediment for several weeks prior to draining.Some dikes in the Columbia Basin are lithified. These dikes are finer grained and generally constructed of a much thinner set of fill bands. Lithified dikes are older than the more common Missoula flood-age dikes, which are late Pleistocene in age. Lithified dikes are early to middle Pleistocene in age, a period sometimes referred to as "pre-late Wisconsin". These dikes also formed during a glacial period and under climate conditions similar to that during Missoula flooding. This older set of dikes intrude flood-related deposits in the Walla Walla and Pasco subbasins. We see this older set as further link between clastic dikes and outburst floods. Thin sections have been made from several dikes and the petrographic analysis of the fill bands and micro-scale cross-cutting relationships is currently underway.