128 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
a 25-foot bed of brown sandstone containing a few cephalopods. This bed is 
thought by some (Kirk, 1933.) to be the lower part of the Eureka sandstone. In 
Lone Mountain, 18 miles north-northwest of Eureka, the main body of the White 
Eureka sandstone is thought to rest on the “lower sandstone,” but in Martins 
Ridge some 350 feet of limestone and shale intervene between the two sandstones. 
Yellow limestone.—Overlying the “lower sandstone” occurs about 150 feet 
of thin-bedded, yellow-weathering limestone abounding in fossils. Generally the 
specimens are not well preserved, and they are not silicified. One of the abundant 
genera is Sowerbyites. The species identified from this bed are: 
Camerella umbonata Cooper Multicostella parallela Cooper 
Camerella sp. 3 M. rectangulata Cooper 
Eoplectodonta alternata (Butts) Oxoplecia monitorensis Cooper 
Isophragma ponderosum Cooper Sowerbyella sp. 4 
Lingulasma occidentale Cooper Sowerbyites lamellosus Cooper 
Macrocoelia occidentalis Cooper Valcourea plana Cooper 
Correlation—The brachiopods listed suggest a correlation with the Arline 
formation of the Southern Appalachians. The relationship is best shown by the 
presence of Isophragma, which has not been seen outside of this horizon and the 
lower part of the Benbolt formation. The presence of Sowerbyites is not an 
anomaly because that genus ranges from the Lincolnshire to the level of the 
Bromide (approximately Ridley-Wardell). The Macrocoelia is also in accord 
with the suggested correlation. The zone in question cannot be lower than Lin- 
colnshire or higher than Benbolt, with the balance in favor of the Arline-Effna 
level. 
Dark shale with Reuschella.—Overlying the yellow-weathering limestone 
are dark shales, about 150 feet in thickness, abounding in brachiopods and other 
fossils reminding one most strongly of the Oranda formation of Virginia. Here 
occur : 
Bilobia hemispherica Cooper Oxoplecia nevadensis Cooper 
Bimuria sp. I Paurorthis gigantea Cooper 
Cristiferina cristifera Cooper Plectorthis obesa Cooper 
Eoplectodonta alternata (Butts) Reuschella vespertina Cooper 
Glyptorthis sp. 1 Rostricellula angulata Cooper 
Hesperorthis antelopensis Cooper Sowerbyella merriami Coopet 
Leptaena ordovicica Cooper Sowerbyella sp. 1 and 2 
Leptellina incompta Cooper Strophomena sp. 1 
Correlation —The Reuschella, Bilobia, Leptaena, and Eoplectodonta are links 
to the Oranda formation. This is corroborated by the presence of the trilobite 
Cryptolithus. The other genera are all more or less common in the Virginia 
formation. 
Eureka quartzite.—The main mass of the Eureka, sparkling quartzite, white 
and heavy-bedded, overlies the dark shales. It underlies the Hanson Creek for- 
mation of probable Maquoketa age. This fixes the level of the Eureka as probably 
middle or high Trenton. 
