Detailed mapping in the Sierra Madre Occidental, near Durango City, Mexico, has documented more than 700 m of rhyolitic volcanic rock (Río Chico Formation) overlain by basaltic lava-flow rock (Metates Formation). The Río ...

The Edwards Limestone (Albian) is a mosaic of shallow water, back-reef, carbonate lithofacies averaging about 450 feet thick, that have been dolomitized, chertified and dedolomitized. Intermittent subaerial exposure during ...