FAEMINGTON AND WEBER EEGION. 377 



out the aid of fossils, the Sub-Carboniferous and Devonian formations have 

 been included within this body. Directly underlying it is a zone of slialy 

 quartzite, passing down into a solid white quartzite, the whole having a thick- 

 ness of about 800 feet, and holding the position of the Ogden Devonian, as 

 it has been colored. Under this again are 800 to 1,000 feet of highly 

 crystalline limestones, which, being entirely conformable with the above, 

 had been considered to represent the Ute limestone, on purely stratigraph- 

 ical grounds. Since the completion of the field-work, there have been 

 obtained from the lowest limits of these limestones on City Creek, in a bed 

 of shaly limestone standing at a high angle, and immediately overlying 

 quartzites and schistose rocks, three forms of Trilohites, of which the two 

 following were sufficiently well preserved for identification, and probably 

 indicate the horizon of the Potsdam group: 



Ogygia parabola (also found at Ophir City, Oquirrh Mountains). 



Crepicephalus (allied to Conocephalites (Crepicephalus) diadematus). 



On the summit of the range directly east of Centreville, and under- 

 lying the Ute limestone, lies a conformable series of quartzites, the upper- 

 most member of which is the same salmon-colored conglomerate-bearing 

 quartzite which underlies the Ute limestone generally in the Wahsatch. 



This series, with the exception of the underlying quartzite, which is 

 considered as Cambrian, may be observed in the south branch of Mill Canon 

 above the saw-mill, and are here seen to rest unconformably upon an older 

 body of Archaean schists. This body extends northward as far as the canon 

 next Mill Canon, and consists of intensely metamorphosed material of an 

 ashen-gray color, composed of quartz, orthoclase, and muscovite. It weath- 

 ers with an excessively rough surface, developing curious wavy lines, and 

 appears to have been a body of quartzitic schists, containing a little ortho- 

 clase and mica, which have undergone the most violent compression and 

 crumpling, obliterating entirely the original bedding, and leaving only 

 obscure traces of short, abrupt, and extremely irregular corrugations. 

 To the northward, it probably passes unconformably under the main series 

 of gneisses and schists, which form the main body of the range east 

 of Farmington. Although the contact was not actually seen, yet the 

 regular dip and strike of the gneisses and schists continue close down to this 



