GEOLOGICAL SUEVEY OP THE TERRITORIES. 15 



limited in extent. The lowest bed of quartzites resting upon the granit- 

 oid rocks I have estimated to be 1,500 to 2,000 feet in thickness. It has 

 a very brittle fracture, although so hard and compact, usually very fine, 

 and, to the naked eye, without grain, but it is sometimes composed of 

 an aggregate of water-worn pebbles, mostly quite small, or crystals of 

 quartz. This lower bed has evidently been more or less changed by 

 heat, and the external evidence of change grows fainter as we proceed 

 up from the quartzites into the limestones, until all traces of it disappear. 

 In regard to the age of these quartzites there is much obscurity. So far 

 as my own investigations are concerned, I only know that they attained 

 a great thickness — that they seem to form the lower portion of the shaly 

 sedimentary rocks of this region. The discovery of the well-known 

 Silurian coral, Halysites cateniUaria, in the last bed of limestone, points 

 to a Silurian horizon. The texture of the rocks in these mountain 

 ranges renders the discovery of fossils in great numbers and in a good 

 state of preservation quite doubtful. We shall wait for the report of 

 the more careful investigations under the direction of Mr. Clarence 

 King. The Carboniferous group in this region is well defined by its fos- 

 sils,. and, I have no doubt that the Silurian and Devonian are well repre- 

 sented. It may be that all the lower quartzites should be embraced in 

 the Silurian. If opportunity presents, I hope to discuss these obscure 

 points more in detail in the closing chapter of this report. 



The same remarkable illustrations of mud-flats and shallow water 

 deposits as occur in the quartzites of the Uintah Mountains are 

 seen here. Some of the layers are closely crowded with rather coarse 

 fucoidal stems or roots, suggesting the Devonian age. As is quite well 

 shown on our maps, the ranges of mountains west of longitude 111° 

 have a trend nearly north and south, or perhaps, more accurately, west 

 of north and east of south. Many of the little streams that empty into 

 the lake pass through the Wahsatch Eange at right angles, or nearly 

 so, thus forming the deep and picturesque canons for which this basin 

 is so remarkable. Cross-sections of the mountains are thus exposed, 

 enabling the geologist to work out with considerable clearness the order 

 of superposition of the beds ; though, with all these advantages, it is 

 not always an easy task. Sometimes the strata are much crushed and 

 folded, or concealed by recent deposits or debris. 



On the morning of June 4, I made an exploration up Ogden Canon, 

 which forms an excellent example of the cross-sections referred to above. 

 A fine creek about 30 feet wide and 3 to 5 feet deep has cut a channel 

 through the mountain and its ridges. The stream, as it comes out of 

 the mountain on the west side, opens into a broad grassy valley, thickly 

 settled by farmers, and joins the Weber Eiver about five miles dis- 

 tant. Five miles from the entrance of the canon to the eastward there 

 is an expansion of the valley, with table-like terraces on the north side, 

 on one of which a Mormon village is located. The terraces are 30 to 50 

 feet above the bed of the creek. On the northeast side of this valley are 

 hills 800 to 1,000 feet high, composed of arenaceous clays, with some 

 beds of limestone, while east and southeast are numerous ridges of 

 limestones with corals and other fossils, showing them to be of Car- 

 boniferous age. The north and northeast sides of the hills are rounded 

 and sloping, and covered with coarse bunch-grass and small bushes. 

 The valley is full of springs and meadow-like areas. The scenery can 

 hardly be surpassed in any country for wild, picturesque beauty. The 

 character of the rocks in the order of superposition does not differ mate- 

 rially from those exposed in the valley of the Weber Eiver, along the line 

 of the Union Pacific Eailroad. There are the Tertiary beds of the Wah- 



