CORRELATION. 63 
Correlation of rocks of the Iron Springs district with rocks of the Colob Plateau. 
Colob Plateau. 
Huntington and Goldthwait. 
Basalt. 
Dutton. 
Iron Springs district. 
Quaternary sand, gravel, and Quaternary sand, gravel, and 
clay. clay. 
Basalt. 
Pleistocene gravels. 
Pleistocene conglomerate. 
Trachyte, andesite. 
Andesite, trachyte, rhyolite. 
Andesite, trachyte, rhyolite.etc. 
Tertiary limestone, shale, and 
conglomerate. 
Tertiary limestone, shale, and j Claron limestone, including some 
conglomerate. sandstone and conglomerate. 
Cretaceous sandstone, shale, and 
limestone. 
Cretaceous sandstone, shale, and Pinto sandstone, including some 
limestone. shale, conglomerate, and lime- 
stone lenses. 
Colob sandstone. 
Jurassic shale. 
Jurassic sandstone. 
(?) 
Kanab sandstone. 
Painted Desert sandstone and 
shale. 
Shinarump conglomerate. 
Triassic sandstone, shale, and 
conglomerate. 
(Missing.) 
Moencopie shale and sandstone. Permian shale and sandstone. 
Super-Aubrey shale and lime- 
stone. 
Aubrey limestone. 
Carboniferous limestone. 
(Missing.) 
Homestake limestone. 
The fossils found in the Homestake limestone are few and poorly 
preserved. They were referred for determination to Prof. Eliot 
Blackwelder, of the University of Wisconsin, and Dr. George H. 
Girty, of the United States Geological Survey. Professor Blackwelder 
determined some of the better preserved forms as Aviculopecten, a 
genus ranging from Silurian to Triassic, but here probably Carbon- 
iferous. Doctor Girty says: 
The specific determination of these forms is hardly possible from the imperfect con- 
dition of the material. . . . I believe that should you obtain more complete col- 
lections they would prove that the beds from which they were obtained should be 
correlated with that portion of the Wasatch Mountains section which the geologists 
of the Fortieth Parallel Survey designated the Permo-Carboniferous. This is likely to 
be the highest Paleozoic horizon found in your region. 
The overlying Pinto formation is satisfactorily determined as 
Cretaceous. The Homestake limestone could not be Jurassic, accord- 
ing to its fossils, and since the limestone is dissimilar to the Triassic 
and Permian sediments of the adjacent High Plateaus, which arc 
masses of sandstone and shale, it is referred to the next preceding 
period, the Carboniferous. Specific correlation with the Aubrey 
(Carboniferous) limestone naturally suggests itself, but it differs much 
from the latter in appearance and lithologic character, in that it is 
more sandy, shows bedding plainly, and is yellow, while the Home- 
stake limestone is a pure, massive, dark-blue-gray limestone, lacking 
a conspicuous bedding. 
