Diapir of red silty till extruded through sandy carapace of a mudboil
The till plain between Victory and Townsend Lakes is formed on red, silty-clay till, derived in part from sedimentary rocks and red volcanic porphyries of the Precambrian Dubawnt Group, which crop out more than 100 km to the northwest. The color contrast between unmodified till and the sandy carapace through which the diapir has penetrated makes it very easy to see these structures in this area. The red color of the till is primarily the result of a pigment composed of clay-sized, crushed specular hematite, which constitutes over half of the sand-sized, non-magnetic heavy minerals (S.G. >3.3) of this till. When the till is modified by washing at the surface, the red pigment, which is largely in the clay and silt sizes, is removed, creating a reworked, sandy, rigid residue, which forms the carapace structures of a mudboil. Traces of dikes and diapirs of the red till on the till plain are marked by light gray to white patches or linear features, such as those evident in images 0090, 0099, and 0216. I believe that this image and other views of this particular feature were exposed by excavation of one of the linear white areas on image 0090. Images 0059 and 0091 are different views of the same excavation as image 0055. See detailed discussion for image 0240.
Updated 05/06/2010 AW