84 SUEVEY OF COLORADO AND NEW MEXICO. 



At one locality I saw a remarkable intrusive layer between the red or 

 variegated beds whicb are supposed to be triassic and the Jurassic. It 

 is a very compact, heavy syenite, and forms a ridge of upheaval, and 

 dips in the same direction and at the same angle with the unchanged 

 beds above and below. 



About four miles below the first basaltic caiion on Grand Eiver, 

 aj)parently the same ridge comes close to the river again. On the north 

 side there is a high basaltic uplift, which shows well marked lines of 

 stratification, as if the melted material had been poured out in thin reg- 

 ular sheets or layers. The dip is about north. In many places the 

 entire mass is made up of a coarse conglomerate, and has the peculiar 

 steel color which seems to characterize modern erui^tive rocks. The dip 

 of this basaltic ridge, at this point, is thirty-six degrees. On the oppo- 

 site side of the river there is an isolated i^ortiou cut off from the main 

 ridge, with a dip about south or southeast twenty-four degrees. 



Continuing our way west down Grand Eiver we pass over a series of 

 upturned ridges of sedimentary rocks, inclining in the same direction 

 with the basaltic ridge trending parallel with it, composed of cre- 

 taceous and older tertiary beds. Looking eastward from the Grand 

 Canon, below the hot springs, this remarkable basaltic ridge seems to 

 form a semi-circle with a general dip about north. 



Immediately below the hot springs the Grand Caiion commences, 

 and the river cuts its way through an upheaved ridge of massive 

 feldspatbic granite for three miles between walls from one thousand to 

 one thousand five hundred feet high. The south side is somewhat sloi^ing 

 and covered thickly with pines, while the north side is extremely rugged, 

 the immense projecting masses of granite forbidding any vegetation to 

 gain a foothold. It would seem that the river had worn its w^ay through 

 a sort of rift in the granite, but at the upper end it has cut through the 

 uplifted sedimentary ridges nearly at right angles. In some places the 

 north side is gashed out in a wonderfully picturesque manner, so that 

 isolated columns and peaks are left standing, while all the intermediate 

 portions have been worn away. This granite ridge will average perhaps 

 five miles in width, and extends an unknown distance across the i)ark 

 northeast and southwest, and it is from the southeast side that the 

 ridges of upheaval above described incline. 



The granite ridge seems to form a sort of abrupt anticlinal. On the 

 southeast side the rocks are all bare or covered with a superficial deposit 

 of recent tertiary marls. I»[one of the older unchanged rocks are seen 

 on this side, but the modern sands and sandstones are exposed in a 

 horizontal position in the channel of the river. 



The hot springs are located on the right bank of Grand River, at the 

 juncture of the sedimentary rocks with the granites. Just east of the 

 springs is a high hill. Mount Bross, one thousand to one thousand two 

 hundred feet above Grand Eiver, which seems to be coraj)osed mostly of 

 the older tertiary strata, alternate yellow and gray sandstones, and lamin- 

 ated arenaceous shaly clays. The whole is so grassed over that it is diffi- 

 cult to take a section. The beds incline east of north at a small angle. 

 I regard the beds as of the age of the coal formations of the West, older 

 tertiary. I found excellent imjiressions of deciduous leaves, among 

 which are those of the genus Magnolia. Just opposite the springs, the 

 left bank of the river shows a perfect section of all the layers from 

 the cretaceous to the Jurassic. The bank is not more than ten 

 feet thick above the water, and yet it shows that the river itself rolls 

 over the upturned edges of all these beds. 



