THE CHINLE GROUP

OF

NORTH EASTERN ARIZONA

ROCK POINT FORMATION

(Uploaded 1/3/09)

A red flagstone type unit primarily from Gallup, New Mexico to the Arizona border. Deposition environment included mud flat, and eolian sand sheet and eolian dune deposits. It is the primary tetrapod footprint unit of the Chinle as well, containing dozens of ichnofauna species whose track makers are primarily reptilian in origin. The Chinle is overlain by the Jurassic Wingate, and Entrada Sandstones.

30 miles down highway 602 from New Mexico into Arizona, the best exposures in the state of Rock Point formation can be seen. Thinly bedded sandstones that split into sheets is its primary lithology.

A lower unit at the site was more massive, and formed this road cut along highway 602.

The lower massive unit consisted of a fine grained orange sandstone with fine laminar bands, but no cross bedding. This is typical of deposition in a fluvial environment.

Another view down highway 602 of the Rock Point, the beds were typically up to several feet in thickness and could be traced for thousands of feet.

Just over into the New Mexico border, we found the Zuni Buttes composed of Rock Point sandstone were similarly bedded to those in Arizona.

Also seen here in the Zuni Buttes, the same lower massive unit was found indicating the same depositional unit as in Arizona. Formations are not restricted to geographic boundaries and States, but often straddle several states.

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