[9] The Cable Canyon Sandstone is present in the northern exposures of the group and lies unconformably on the El Paso Formation.

In the Franklin Mountains, the upper El Paso Formation shows pronounced karst weathering.

[9] The group is interpreted as having been deposited within 30 degrees of the equator on the subtidal zone of a passive continental margin during the transition to late Ordovician glaciation.

The presence of abundant chert and phosphate minerals in the group is attributed to upwelling along the continental margin, possibly triggered by glaciation.

The Upham Formation is rich in fossils, including brachiopods, bryozoans, corals, crinoids, gastropods, nautiloids, and receptaculids.