Seismite Indicates Pleistocene Earthquake Activity in Ellis County, Kansas

The post-Precambrian stratigraphic record is incomplete with one estimate that 80 percent of time is not represented (Merriam, 1963). Even so, there is ample evidence that the craton has remained active through time as recorded by the soft-sediment deformation that occurs in the record. Soft-sediment deformation or convolute features occur when the sediment is yet in a semi-liquid state and a trigger (earthquake) causes the sediment to deform by dewatering (Fig. 1). The soft-sediment deformation which forms convolute features has been adequately described in the geological literature and are referred to as seismites.