156 



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

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

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

 canon are capped by the bluish strata of the higher Ko. 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 reach Cunningham 

 Gulch. Traversing the caiion, 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. 



Proceeding to the head of Cunningham Creek, the volcanic rocks are 

 seen only as forming the crests of ridges, while the main drainage runs 

 over metamorphic rocks. Station 17, near the head of the creek just 

 mentioned, is located on gneiss, and may be regarded as one of the out- 

 posts of the metamorphic area already mentioned. From there the line 

 of outcrop extends east and southeast on the one side, west and south 

 on the other. Local accumulations of mica or quartz change the lith- 

 ological character of the rock, and the appearance of chlorite in it gives 

 rise to a continuation of the metamorphic area to the southeast as chlo- 

 rite schist, the rock composing the lower portions of the Cunning- 

 ham walls, and containing a number of ore-veins. Further down on the 

 Animas, where these metamorphic rocks should be exi^ected to crop out, 

 within a few miles below Baker's Park, on the Animas caiion, we find 

 nothing but volcanics. Along either side of the river, from Cunning- 

 ham Gulch downward to the point just given, volcanic rocks appear to 

 form the entire mass in view. Although the lower portions of the rocks 

 exposed probably do not belong to No. 3, it is very difficult to identify 

 them with any one of the underlying groups, and they must be referred 

 to a position near to or in intimate connection with No. 4. Owing to a 

 large quantity of debris in Arastra Gulch, the majority of lodes thus 

 far discovered have been claimed at an elevation of more than 1,000 

 feet above the creek. At no point in that gulch have I observed crop- 

 ping out of metamorphic schists, although I have reason to believe that 

 they really do underlie the volcanic material. This suspicion is based 

 upon the character of the Little Giant ore, which contains chlorite and 

 none of the minerals mostly found in the trachorheites. Prospecting 

 has also been done farther down the river, but as my time was limited, 

 I had no opportunity of visiting any of the lodes there located. 



The conditions on the west side of the Animas appear to be of a more 

 simple character, the metamorphic rocks not reaching over in such a 

 manner as to crop out, although at some depth they may i)robably be 

 found. It is possible that considerable erosion took jplace before the 

 volcanic flows invaded the reeions, and before the lodes were formed — 



