400 DESCRIPTIVE GEOLOGY. 



limestone, passing- into a gray granular limestone, the upper portion of which 

 is more or less characterized by shales. So far as known, no fossils have 

 ever been found in the Ute limestone of the Ogden Cafion, except some 

 fragments of Stromatopora^ too much altered for specific identification. 



The Ogden Quartzite immediately succeeds these calcareous shales, 

 overlying them conformably, with a thickness which has been estimated at 

 about 1,250 feet. It is a pale-reddish or yellowish-white quartzite, of me- 

 dium-grained texture and conspicuous jointing planes. Under the micro- 

 scope, occasional grains of quartz reveal the presence of small liquid-inclu- 

 sions, with very mobile bubbles. Subjected to chemical analysis, it yielded 

 97.792 per cent, of silica. At the top of the formation are a few feet of 

 olive-colored argillaceous shales, which separate it frona the great body of 

 the Wahsatch limestone. 



This formation extends to the upper limits of the cafion, exposing a 

 thickness of not less than 4,000 to 5,000 feet. Most of the lower beds are 

 coarsely crystalline, more or less siliceous and cherty in places, and carry- 

 ing not unfrequently narrow bands of argillaceous muddy material. Near 

 the upper limits of the canon, a singular crumpling has taken place within 

 the beds, by which 500 or 600 feet of strata are bent into the form of a Z. 

 The material of this crumpled portion is very black, fine-grained limestone, 

 which is interrupted by frequent thin beds of impure siliceous and muddy 

 material. A similar contortion is seen lower down on the south side of the 

 canon, near the edge of the stream. These contortions do not penetrate into 

 the lower members of the group, nor do they affect the highest members 

 seen in the canon, the latter passing over the crumpled zone without follow- 

 ing its waves. About 1,200 feet up from the base of the limestone was 

 found a collection of fossils, which, while having a general Waverly aspect, 

 also contain some distinctly Devonian forms, and may be therefore consid- 

 ered to indicate somewhere near the dividing-line between the Devonian 

 and Sub-Carboniferous formations. The species determined by Messrs. 

 Hall and Whitfield were : 



Produdus, sp.?, 

 Spirifer alba-pinensis, 

 Spirifer centronatus, 



