116 ANNALi^l NEW YORK ACADEMY OF i^CIENCES 



a cavernous weathered surface of fossiliferous gray limestone. Just 

 above the contact lies a coarse sandstone which consists of well-rounded 

 frosted sand-grains bound in a deep red matrix and including bits of 

 limestone and black chert from the underlying series. Although the 

 bedding of the Morgan formation is essentially parallel to that of the 

 limestone below, the relations here clearly indicate a disconformity, sig- 

 nifying an erosion epoch between the Mississippian and the Pennsylva- 

 nian." From faunas obtained above the disconformity, whicli sliow close 

 relationships, the erosion interval is thought to be geologically brief in 

 that region. 



Dr. C. P. Berkey^^ has also described an unconformity at the base of 

 the Weber quartzite in the western Uintas. He says in part: 



"The base of the overlying formation, chiefly quartzite, is a true basal 

 conglomerate. There are abundant fragments and pebbles and boulders from 

 the eherty limestone bed immediately below, and in some places the finer 

 cementing or filling matter is calcareous rock flour (calcilutite) and granular 

 limestone (calcarenite) and chert (silicarenite). Fossils are abundant below 

 the break but rare above it in this area. Fi-om the above, it is certain that 

 there is an erosion disconformity in the Upper Carboniferous of the Uintas 

 that marks moderate readjustment of levels, so that the strata are not perfectly 

 conformable in angle, although the later folding of the range has been so much 

 more profound that this is lost sight of except along the immediate break." 



In the western Uintas, there are two strongly developed quartzites. 

 Barring discrepancies in thickness and noting only succession, the upper- 

 most one of these would appear to con'cspond to the true '^'^Weber." The 

 erosion break occurs here at its base. While Berkey puts the discon- 

 formity into the Upper Carboniferous, he establishes the fact that it 

 occurs below the Weber quartzite, which corresponds exactly with its 

 position in the Big Cottonwood section. Many of the details of descrip- 

 tion also correspond, such as the prevalence of eherty pebbles and much 

 fine material and slight discordance of dip between the upper and lower 

 layers. An absence of fossils above the break in these two sections is 

 also significant. In the northern Wasatch sections at the base of the 

 Morgan formation, fossils occur in limestone layers, showing, according 

 to Dr. Girty, that the unconformity there corresponds to a brief time 

 interval. To decide the value of the unconformity, it is only necessary to 

 find a section not too remote which shows no break and compare it with 

 the Wasatch sections and Berkey's western Uinta section. Such a one 

 is to be had at Mercur in the Oquirrh Mountains. 



2^C. p. Berkey: "Stratigraphy of the TMnta Mountains. T'tah." Bull. G. S. A.. Vol. 16, 

 pp. r)24-527. 1905. 



