The elevation of the Zuni Mountains is due to a major uplift of the geological strata called the Zuni uplift. This northwesterly trending anticline is deeply eroded, exposing the pre-Cambrian core. Cretaceous and older sedimentary strata once covered these mountains. The total elevation of the original Zuni uplift can be estimated from the thickness of the sedimentary rocks surrounding the current mountains, 4100 feet of Paleozoic rocks, 9500 feet of Mesozoic rocks, and 6600 feet of Cenozoic rocks -- 20200 feet total -- have been eroded from the summit of the Zuni Uplift, These mountains are still over 9000 feet at their highest point!
The remains of these layers are now seen in concentric rings around the mountains, with the harder layers rising out of the surface as tilted, sandstone capped ridges, and the softer layers forming valleys between these layers. The town of Ramah lies in one of these valleys, between a Cretaceous ridge to the south and a Jurassic ridge to the north. El Morro National Monument, where passing travellers for centuries have inscribed their names (more graffitti! this time enshrined as a National Monument) is also one of these eroded ridges.
References
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© 1994 Karen M. Strom
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