The Elder Sandstone was named by Gilluly and Gates (1965) for exposures 8 miles southeast of Mount Lewis in the Shoshone Range. The "hill extending from the sharp bend of Elder Creek in Sec. 30, T. 28 N., R. 46 E., to the Utah Mine is designated as the type locality."

Both the lower and upper contacts of the Elder Sandstone are faults wherever exposed, making its original relationship to units such as the Valmy or Slaven Chert cryptic (Gilluly and Gates, 1965; Stewart and McKee, 1977). Fossils are quite sparse in the Elder, however Middle Silurian graptolites have been found in two localities in the Shoshone Range (Gilluly and Masursky, 1965; Gilluly and Gates, 1965). The Elder Sandstone is probably an equivalent of the Roberts Mountains Formation and is here considered Llandoverian in age.

The Elder Sandstone is a fine-grained, yellowish-brown, moderately cemented, feldspathic silty sandstone, with interbeds of siltstone, tuffaceous shale, and thin, gray to yellow-brown chert (Gilluly and Gates, 1965, Gilluly and Masursky, 1965). Minor quartzite and cherty shale are also present with the Elder which is metamorphosed to lower greenschist facies.

These distinctive yellowish sandstones contain 10-20 percent potassium feldspar, and 5 percent muscovite, but the main mineralogical constituent, 70 to 80 percent, is quartz (Gilluly and Masursky, 1965). They show ripples and small-scale cross-bedding, as well as fine, planar laminae up to one quarter inch thick (Gilluly and Gates, 1965). Euhedral pyrite is common in the sandstones, making up as much as 3 percent of some rocks, and giving the yellow-brown hue to the formation as a result of its oxidation. Some of the sandstone contains white porcelaneous grains which are probably devitrified glass shards, and grades into what are essentially siliceous ash beds (Gilluly and Gates, 1965). The siltstones also have the same general mineralogical composition as the coarser sandstones, and contain ghosts of pumice shards suggesting a volcanic component. The shales are also tuffaceous and may represent reworked siliceous ash (Gilluly and Masursky, 1965).

Although exceedingly rare, tan, light-brown, and gray cherts are present within the Elder. They rarely exceed 3 feet in thickness. The cherts contain as much as 20 percent sericite and 10 percent potassium feldspar suggesting a pyroclastic origin.

Faulting along both the upper and lower contacts of the formation, as well as local isoclinal folding, make thickness estimation difficult. Gilluly and Gates (1965) speculate that a thickness of 2,000 feet at a minimum and probably 4,000 feet of Elder Sandstone may have been present in the Shoshone Range.

The Elder Sandstone is exposed within the Shoshone and southern Sheep Creek Ranges.

The Elder Sandstone is essentially a shallow marine volcaniclastic sequence deposited under the influence of sediment gravity flows (Girty and others, 1985). Gilluly and Masursky (1965) speculate that the upwards coarsening of the Fourmile Canyon Formation may have continued into the Elder Sandstone, and the two may be part of a consistent sequence deposited in a site which is now structurally dismembered. Lee (1978) felt that the small and large-scale coarsening upwards sequences, grading, horizontal and climbing ripple cross-lamination, and thin sandy channels in the Elder Formation suggested distal turbidities. The Elder does not contain sole markings.

Work by Girty and others (1985) shows that the Elder contains rock fragments of Paleozoic carbonate, argillite and chert, quartzite, and intermediate to mafic volcanics. Detrital zircons in the unit are dated at 2.2 Ga. and suggest that along with a Paleozoic source terrain, a Precambrian crystalline terrane may have also supplied sediment to the Elder Sandstone. Such a terrain would have been positioned west of the continental margin of North America during the Silurian.