230 GEOLOGICAL SUEVEY OF THE TEREITORIES. 



considered by the prospectors as very promising. A settlement lias 

 been made at Howardsville, on the Animas, this being a point more 

 favorable, perhaps, than many others, having the additional advantage 

 of being centrally located with reference to the mines. At the bend of 

 the Animas, near the base of Sultan Mountain, station 26, is Baker's 

 Park proper ; there is a settlement called Silverton. A short distance 

 to the east of Silverton is Arastra Gulch, which became well known 

 some years ago by the discovery of the " Little Giant" mine, and now 

 contains a number of others. In a similar position to Howardsville is 

 Cunningham Gulch, with a number of promising lodes, as yet compara- 

 tively undeveloped. Besides these points, prospecting and mining to a 

 small extent are carried on throughout the entire vicinity, both on the 

 mountains and in the caiions. Smelting-works were in the course of 

 erection at Silverton when visited by our party, but, as I am informed, 

 were not completed satisfactorily. 



Geognostically, the northern portion of the district just described 

 shows scarcely any important variation from the general character of 

 the surrounding country. All the rocks of that part, so far as I have 

 had occasion to observe, are volcanic, exhibiting, as at many other 

 neighboring points, a great variety in texture^and mineral constituents. 

 From stations 13 and 14, the No. 4 of our schedule, above given, extends 

 west and southwest, changing in lithological character, although the 

 stratigTai)hical relations remain simple. I am inclined to attach con- 

 siderable importance to this latter feature, all the more so, inasmuch as 

 a satisfactory explanation of the geological relation could otherwise 

 only be obtained after very careful detail studies. The rock upon which 

 station 15 is located is of a grayish to muddy-green color, containing 

 small, irregular fragments of a triclinic feldspar, and some sauidite. 

 Cubical pyrite crystals, of about 0.3™™ edge, are dispersed throughout 

 the rock, giving it, upon decomposition, a brown color. 



Similar in general character, but varying in detail, are the rocks 

 composing the mountains on either side of the Animas down to Silver- 

 ton, and a short distance beyond. They are mainly aggregates, as 

 those from station 15, sometimes containing pyrite as an impregnation. 

 In Cunningham Gulch, the lower portions are of a dark-gray color with 

 a greenish tinge, while the higher portions of the hills bordering the 

 caiiou are capped by the bluish strata of the higher No. 4, as described 

 above from Handle's Peak. In Arastra Gulch the rock containing the 

 lodes higher up on the mountain-sides closely resembles that of station 

 15 at some points, while at others, without any great change in the 

 vertical direction, it answers more to the bluish variety. From all that 

 I could observe, however, I have come to the conclusion that the lode- 

 bearing rocks of Baker's Park belong to that trachyte series which has 

 been designated as No. 4. 



This feature of regularity disappears when we study Cunningham 

 Gulch. Traversing the canon, whose walls rise 3,500 feet above the 

 creek, it will be perceived that the dark colors of the rocks still pre- 

 dominate, but that the lower portion of the steep walls has a tinge of 

 gray and green, and- is not horizontally stratified. This might, upon a 

 cursory examination, lead to the conclusion that the lower rocks, show- 

 ing weathering in a vertical rather than horizontal direction, were co- 

 lumnar trachyte. A short distance below the elevation at which the 

 " Highland Mary " and several other lodes are located, a sharply-marked 

 horizontal line may be observed, very slightly inclining toward the west. 

 Above that line the rocks are horizontally stratified, varying from a 

 bluish to a maroon color — the trachyte No. 4. 



