Polished slab of aphanocrystalline dolomicrite from the upper part
of the Seven Rivers Formation. Wispy remnants of lamination are an
indication of extensive bioturbation but calcified skeletal fragments
are extremely scarce in these strata. Dolomite here, as in most of
the Permian shelf deposits of this region, appear to be a very early
diagenetic replacement resulting from the reflux of hypersaline to
mesosaline lagoonal brines. Slab from roadside outcrop along New
Mexico Highway 137 in western Rocky Arroyo, Eddy Co., NM.

© Peter A. Scholle, 1999

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