200 GEOLOGICAL SUEVEY OF THE TEKEITOEIES. 



portions contain very numerous individuals of a few species of fresh- 

 water shells, which are sufficient to mark the bed as of late Tertiary 

 (Pliocene ?) age. (Dr. Curtis, of our party, afterward obtained from the 

 shore at the southern end of Salt Lake specimens of oolitic sand, which 

 show that this kind of calcareous deposit is still forming abundantly in 

 this basin.) The beds exposed are about 200 feet thick. They show, at 

 this point, a dip of about 25° south, 68° west. As no corresponding 

 disturbance of the surface of the terraces is apparent, it is evident that 

 the upheaval antedates the Terrace epoch. The lower terraces show 

 extensive deposits of coarse gravel, which is well exposed in the cuts of 

 the Utah Northern Eailroad, and supplies that road with an abundance 

 of superior ballast. 



After crossing Bear Eiver, the Tertiary limestones are found covering 

 the entire foot of the mountain, for two or three miles, though the mount- 

 ain itself is still plainly comiDosed of the older limestone, which appears 

 on its summit. Then the Tertiary disappears altogether, and the upper 

 quartzite rises so as to form the face of the ridge, for four or iive miles. 

 Then the Tertiary comes in again, in a heavy body of compact flinty 

 limestones and siliceous shales, running to the very tops of the hills, 

 which are here much depressed. The strata are mainly nearly level, 

 only the portion nearest the valley having a westerly dip, which at some 

 IDoints reaches 40°. About nineteen miles above Hampton's Bridge, the 

 mountain rises again, and the Tertiaries disappear again, exposing the 

 face of the lower limestone, which has now risen so as to form the en- 

 tire mass of the mountain. At the junction of the two series of strata, 

 it is evident that the Tertiaries lie unconformably upon the older lime- 

 stones, many layers of which are here crowded with fragments of tril- 

 obitcs and other fossils, which are plainly of the age of the Quebec 

 group. Among the specimens from this locality which have already 

 been worked up, there are at least fifteen trilobites of the genera Gono- 

 coryplie, Bathyurus, DicellocepJialus, Agnostus, &c., five brachiopods, two 

 gasteropods, and one pteropod. As we approach Malade City the mount- 

 ain becomes higher and more precipitous, a point about three miles 

 south of that place being found to be about 2,500 feet above the river. 

 Of this total, about 2,000 feet are exposed in the face of the mountain, 

 the terraces being mostly washed away. All the strata exposed belong 

 to the Quebec Group, and consist mainly of limestones, though including 

 perhaps 200 feet in all of sandstones, partly shaly, but mostly thick- 

 bedded and quartzitic, as well as an indeterminate amount of interlam- 

 inated greenish calcareous shales. The uppermost limestones are com- 

 pact and full of nodules and layers of chert ; the lower ones vary greatly, 

 from pure compact to coarsely fragmentary, to fine-grained silicious, 

 and to oolitic and coarsely concretionary forms. The colors vary from 

 drab to blue, gray, buff, flesh-color, and pale red, sometimes uniform, 

 sometimes mottled and streaked. Some of the beds, of both the lime- 

 stones and the sandstones, would make good building-stone ; but these 

 are rather too high in the section to be conveniently quarried on the 

 face of the mountain ; though they could probably be easily reached by 

 ascending some of the numerous canons which break through the range 

 in this neighborhood. The fossils occur at various levels, from bottom to 

 to of the section, though some portions of considerable thickness are 

 entirely barren. They can be most easily obtained from the tumbled 

 masses of the different beds which lie numerously along the foot of 

 the mountain. As Malade City is only one day's ride, by stage, from 

 Corinne, the locality can easily be visited by collectors who may be pass- 

 ing over the Central Pacific Eailroad. The section should be more care- 



