Oklahoma Unconformity

This is a road cut along the thruway as it passes through the Arbuckle Mountains of Oklahoma, looking west. There is a lot going on in this photo, and so it is more challenging to understand than some of the other images you are working on in this exercise. Try to find and note the following features: 1) the unconformity that separates overlying Pennsylvanian conglomerates from underlying Ordovician limestones, marls and shales, 2) bedding in the underlying Ordovician sedimentary rocks, 3) an intense fracture set in the underlying strata (and not in the overlying rocks), 4) a late fault, and 5) the drill holes from blasting the road cut.

Questions that might arise include the following. What type of unconformity is this, and what is its regional significance? Why is the basal conglomerate so coarse and relatively thick, and the bedding so hard to see? Which way do the underlying strata get younger (are they overturned)?

Link to interpreted version.

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