196 REPORT UNITED STATES GEOLOGICAL SURVEY. 
Hoback and Salt River Valley. But, unfortunately, the facilities were 
entirely insufficient for acquiring a knowledge of the mountain tract 
forming the continuation of this range in the region north of the Grand 
Canon of Snake River, it being impossible to trace out in a satisfactory 
manner the complicated structural features, which obtain with equal 
force in that quarter, from such distant points of view afforded by the 
mountain eminences on the south side of the Grand Canon. The obser- 
vations of Professor Bradley, in 1872, disclosed several folds and extra- 
ordinary local disturbance in the strata comprising the natural section 
exposed in the walls of the Grand Canon, and which doubtless bear inti- 
mate connection with the facts observed during the perhaps more de- 
tailed work of the present season briefly alluded to above. The region 
north of the Grand Cafion is excessively cut up by the combined effects 
resulting from geologic disturbance and subsequent aqueous erosion, some 
idea of which may be gathered from inspection of the topographic charts 
prepared by the survey ; and while the one state of things offers excep- 
tionably favorable facilities for the detail study of local sections, the 
other renders a more general study, especially at this distance, extremely 
hazardous and unsatisfactory. In certain instances the identity of for- 
mations may be confidently recognized, but, in other cases, color or litho- 
logical appearances are insufficient criteria upon which to affirm the 
stratigraphiecal position and age of extensive deposits prevalent in that 
quarter. The outlying gray ridge on the west, which forms the eastern 
barrier of the lower valley of Snake and Salt rivers, is unmistakably 
Carboniferous. . Then succeeds a wide belt, out of which huge ridges 
have been sculptured by the elements from pale-red and buff beds, which 
seem to hold a position high above the latter, possibly forming part of 
the Laramie series, which appears to be much better developed (probably 
due to its being less extensively denuded) in that quarter than in the 
region visited-the present season. And to the east of the latter, extend- 
ing over to the Upper Snake in the vicinity of-the lower portion of Jack- 
son’s Basin, the mountain escarpments exhibit all the lithological ap- 
pearances familiarly ascribed to the Jura-Trias and post-Jurassic forma- 
tions of the region. More than this the nature of the facts perhaps do 
not warrant. But a brief summary of the examinations of that part of 
the latter belt lying along a part of the course of the Grand Canon visited 
the present season is here appended. 
Our route brought us to the Snake, at the confluence of a small tribu- 
tary draining part of the west flank of the John Day ridge, about seven 
miles in a direct line south of the mouth of Hoback’s River. This little 
valley is wholly excavated in the westerly-dipping Jura-Trias deposits, 
the Gryphza bed of the former being well developed in the immediate 
neighborhood of the confluence. Below this point the Snake enters that 
part of its course more properly designated by the term canon. We here 
found on the terraced intervale indications of old placer workings, which 
had been opened eight years ago by a party of miners associated with 
Jeff. Stantiford, a well-known prospector and explorer of this region. 
The enterprise was, however, interfered with by the Indians, since when 
no organized mining operations have been resumed in this quarter.. The 
locality, which is wonderfully interesting, both in its scenic and geologic 
surroundings, was carefully examined by my companion, Mr. Perry, with 
especial reference to the placer deposits and warm and mineral springs. 
A mile or so above this place the Snake changes its southerly course to, 
a westerly direction, which it pursues thence to the debouchure of the 
Grand Cation. The steep hills on the west side of the river, opposite 
and for some distance above the abandoned placer mines, present fine 
