Death Valley Turtlebacks Part 2

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This photo is actually the Copper Canyon turtleback. The steeply dipping red fanglomerates overlying the slip surface are the Copper Canyon Formation. The Mormon Point turtleback is overlain by more gently dipping, Quaternary (?) conglomerates and the contact is not well exposed. The Copper Canyon Formation is well mapped in Harald Drewes "Geology of the Funeral Peak Quadrangle, California, on the East Flank of Death Valley", USGS Professional Paper 413, 1961 although he did not attempt an interpretation of some important features of the unit. Nyborg, 2011, describes the formation in considerable detail and puts the base of the formation at about 5 million years and the upper part at about 3 million years, based on dates for three basalt flows. The upper part of the formation contains a large-rock avalanche that slid into the basin across the alluvial deposits and plowed into the lacustrine rocks in the center of the basin. I estimate the LRA at about 1 km thick in the least-eroded part overlying the lakebeds. The LRA is weakly brecciated and composed of metamorphic rocks. The overlying CCF is poorly exposed. The partly covered white rock along the contact appears to be intensely sheared carbonates possibly remnants of the upper Precambrian carbonate section exposed in many of the ranges to the east and southeast. I mapped the Mormon Point and Copper Canyon turtleback area for my Penn State Ph.D. thesis (J.K. Otton, 1977, unpublished).