ksduch.] SWEETWATER VALLEY METAMORPHICS. 99 



Directly east of Elkhorn Gap we meet with considerable difficulty in 

 disentangling' the intricacies of stratigraphical disturbances. We find 

 that from that point to the termination of the hills at Whiskey Gap, the 

 main bulk is composed of the same metamorphic granite. Descending 

 from the summit Ave find a series of sedimentary beds folded so as to be 

 completely overturned. Beyond these granite occurs again. So far as 

 can be determined without the aid of analysis and microscope, the two 

 granites are entirely the same. The second group, perhaps, shows more 

 decided structure. The two granitic outcrops run parallel with each 

 other until the smaller one is lost under the strata of the Sweetwater 

 Group. 



As we approach Whiskey Gap we find that the main granite of the 

 hills comes to an abrupt termination, and that the ridge immediately 

 opposite is formed by sedimentary beds trending in the same direction. 

 Crossing the gap we observe a dip of the sedimentary strata toward the 

 southwest, but as we go farther east this changes to south, and the 

 granite sets in again. Encroaching upon the sedimentari.es this forms 

 the northern slope of the hills, while the highest portions are formed by 

 Pakeozoic strata. As we reach Sandy Creek Pass we see that the gran- 

 ite has monopolized the bulk of the hills, and that the sedimentary beds 

 still retain their southerly dip. 



In preceding pages I have termed the structure of the Sweetwater 

 and Seminole Hills an anticlinal one. It remains to be stated that the 

 sedimentary strata on their immediate slopes afford but little evidence 

 touching this point, but from the glimpses which could be obtained of 

 beds underlying the Sweetwater Group, this must necessarily be the 

 type of the hills. 



The northern and northwestern portions of the Granite Hills show a 

 difference of structure which led to a more careful examination. It was 

 found that instead of being composed of the same Prozoic granite as the 

 main mass, they were formed by stratified granites, with some horn- 

 blendic schists. Owing to the isolation of the outcrops, it was a difficult 

 matter to reduce them to a system. Enough was seen, however, to 

 indicate that they stand in close relation with the anticlinal upheaval 

 which is marked as B in subsequent sections. Toward the eastern ter- 

 mination of these metamorphics their stratification is particularly plain. 

 It is so apparent, that from a short distance, even, I supposed the rocks 

 to be unchanged sedimentary. The suspicion presented itself that some 

 of the Silurian beds, which elsewhere are found unchanged, might have 

 furnished the material for the granites and hornblendic schists here 

 observed. This could not be proved, however, as the superincumbent 

 Tertiary beds prevent all study beyond the immediate surface of this 

 locality. At this point the areas occupied by metamorphics are detached 

 and of small extent. Dips may be observed which indicate participa- 

 tion in the anticlinal fold above alluded to. 



For the purpose of elucidating the interesting features connected with 

 this range, as well as to show the relations between the oldest rocks of 

 the region, I have constructed a series of parallel sections. They run 

 from south to north, in every instance cutting the Sweetwater Eiver. 



Section III is taken along a line east of Camp Stambaugh. I have indi- 

 cated the existence of the Prozoic granite (a) at some depth. Emerging 

 from, under the Tertiary strata (T) we find the metalliferous schists (&). 

 They are covered, in part, by Potsdam Quartzite {d) which appears in the 

 Little Canon of the Sweetwater. From the evidence obtained farther 

 northwest, I have indicated the younger granites (c) covered by the regular 



