HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 107 



property at Argenta, in Big Cottonwood Canyon, is a good example, and 

 from this occurrence the name Maxfield formation is suggested for the 

 series. 



SILURIAN STRATA 



The presence of Silurian strata in western America was doubted for a 

 long time. It has recently been shown by Kindle,^ ^ however, that the 

 Silurian period is represented in a number of widely separated regions, 

 and among them, in the northern AVasatch. In Green and Logan Canyons, 

 east of Cache Valley, Cache County, Utah, Kindle reports the following 

 fauna obtained by F. B. Weeks : 



Favosites gothlandica Lamark 

 Favosites niagarensis Hall 

 Halysites catenulatus Linn. 

 Zaphrentis sp. 

 Pentamerus ohlongus Sow. 



Below the Paradise limestone which carries these forms, there is a dark 

 colored limestone of undetermined age. Above it there is a dark magne- 

 sian limestone 800 to 1000 feet thick, carrying Devonian types. How far 

 the Silurian strata extend toward the south is not knoAvn. Blackwelder 

 reports limestones 1000 to 1500 feet thick in the northern AVasatch, on 

 the west side of Cache Valley, which lie between the Geneva formation of 

 Ordovician age and the identifiable part of the Mississippian. In the 

 lower part of this limestone series occur Halysites and Favosites, and a 

 brachiopod fauna somewhat higher up is thought by Kindle to be the same 

 as his Pentamerus fauna of the Bear River range. 



From the occurrence of these limestones at Ute Peak, near the southern 

 end of Cache Valley, the Fortieth Parallel geologists gave the name Ute 

 limestone to the Silurian strata of the Wasatch region. Special mention 

 was made of the occurrence of this member at Alta, in Little Cottonwood 

 Canyon, where a limestone 1000 feet thick is boldly exposed above the 

 Cambrian shale on the north side of the canyon. Above this so-called 

 Ute limestone, and separating it from the higher limestone series known- 

 as the Wasatch limestone, are nearly a thousand feet of quartzite and 

 shale, mostly quartzite, which were called Ogden quartzite from their 

 somewhat greater development in Ogden Canyon. Tlie Ute limestone 

 thus appears as a stratigraphic unit between two well-defined quartzite 

 formations in its typical occurrence. In the latter part of tliis report, it 



" E. M. Kindle : "Silurian Fauna in Western America." Am. .Tour. Sci.. 4th Ser., 

 Vol. 25. 1908. 



