It marks the southernmost limit of Jurassic fluvial and lacustrine sedimentary formations, which pinch out to leave a single sandstone body.

The Zuni Sandstone is found south of the I-40 corridor in west-central New Mexico.

At about this latitude, the Todilto, Morrison, and Summerville Formations pinch out to leave a Jurassic section that is almost entirely composed of eolian sandstone.

This is designated as the Zuni Sandstone, which is thus the lateral equivalent of the combined Entrada and Bluff Formations.

[1] At the type section at Dowa Yalaane (Taaiyalone Mesa), the formation consists of about 80 meters (260 ft) of eolian sandstone corresponding to the Entrada Formation.