WEBER QUARTZITE 531 



mation of Pennsylvanian age to which they gave the name "Weber 

 quartzite/' According to the original measurements the formation is 

 5,000 to 6,000^^ feet thick. A similar quartzite has been found in the 

 Park City district to the south and in Big Cottonwood Canyon, southeast 

 of Salt Lake City, but it has not been identified from Ogden Eiver north- 

 ward, so far as the writer can learn. 



Last summer the writer traced the outcrop of the quartzite northward 

 from the type locality, and in doing so found that it grows thinner and 

 finally disappears about 7 miles north of Weber River. If the Paleozoic 

 formations were fully exposed in this locality, the interpretation of this 

 disappearance would be comparatively easy; but the facts are obscured, 

 because the Eocene deposits come in from the east and cover all of the 

 beds above the Weber quartzite at the point where the latter disappears. 

 However, it is significant that when the Pennsylvanian strata do reappear 

 4 to 5 miles farther northwest, the Weber quartzite is missing, and the 

 Pennsylvanian phosphatic series^^ (the Park City formation of Boutwell) 

 rests directly on the Mississippian limestone. -The structure is simple 

 and outcrops are sufficiently good, so that faulting can not be appealed to 

 in this region. In all other sections observed from here north and north- 

 west the same relation holds. 



Farther northeast, on the eastern slope of the Bear Lake valley, Gale^^ 

 has found the Weber quartzite generall}^ present, but varying considerably 

 in thickness. 



A closer examination of the sequence shows also that the sandy beds 

 which mark the base of the Park City formation rest not on one, but on 

 several members of the Mississippian system, as shown in the accom- 

 panying sections. The shale and limestone member at the top of first 

 and fourth are missing in the other sections. These beds are peculiar, 

 because the shales are purple and the limestone nodules bright green 

 mottled with red, and in addition they are richly fossiliferous. For these 

 reasons the strata are not likely to be overlooked. Furthermore, the 

 fauna in these beds is correlated by Cirty with the Kaskaskia fauna of 

 the Central States, and therefore may be supposed to be older than the 

 fauna at the top of the Mississippian limestone in Weber Canyon, which 

 Girty refers to the early Pennsylvanian. Unfortunately, in these sections 

 the exact contact was not visible, and for that reason the evidence loses 

 some of its cogency. 



^ To the writer these measurements seem excessive ; but as he has made no exact 

 observations to test their accuracy, he can only register a doubt. 



22 The Carboniferous beds are described in the writer's paper, "Phosphate deposits 

 near Ogden, Utah." U. S. Geological Survey, Bulletin 430, Contributions to Economic 

 Geology, 1909. 



» Hoyt S. Gale : Personal communication. 



