The Cambro-Ordovician sedimentary succession in central East Greenland is considered to represent deposits formed during a slow, westward-advancing marine transgression. The sandstones, shales, limestones, and dolostones comprising the succession range in age from Early Cambrian through Middle Ordovician (Champlainian) and appear to reflect patterns of deposition comparable to modern shallow-marine shelf sediments. The roughly 3,000 m of Cambro-Ordovician strata lie with apparent conformity on Precambrian rocks of glacial and marine origin and are superposed unconformably by Devonian "Old Red" fluvial deposits. Tidal current-bedding structures in the sandstones exhibit a marked bimodality with vector means on the east and presumably downslope. Intraformational flat-pebble or flake conglomerates, stromatolitic algal structures, oolitic textures, and desiccation phenomena in the shale and carbonates also favor a shallow marine environment for these deposits. Measured sections at 2 widely spaced localities demonstrate a remarkable lithologic lateral continuity presumed attributable to deposition on a broad marine shelf with very low relief.

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