6 DESCRIPTIVE GEOLOGY. 



broad table-like country, with here and there a few landmarks that have 

 escaped erosion, rising above the general level for 400 or 500 feet. Signal 

 Peak, near the head of Box Elder Creek, which presents a commanding 

 view of the southern portion of the Laramie Hills and of the Colorado 

 Range, is a characteristic point. 



On the summit of the range, tree growth is very limited, although, 

 over the entire area, there are on the slopes of the hills and under the 

 shelter of the larger rocks many small groves of pine, sufficient to make 

 the view picturesque, but not enough to be of much practical importance. 

 In a few localities in the larger sheltered basins of Crow, Lodge Pole, and 

 Horse Creeks are considerable bodies of good timber, but possessing no 

 great vigor of growth. Saw-mills have been erected in one or two locali- 

 ties on Crow Creek. Aspen-groves add to the beauty of some of the upper 

 basins. The streams are all too narrow to afford any good bottom-lands, 

 and the only attempts at cultivation are one or two small ranches on Dale 

 Creek. 



In geological structure, the Laramie Hills form a single anticlinal range, 

 one of the most marked to be found within the limits of this survey. 



Its central mass, a heavy body of metamorphic granites and granitoid 

 rocks of Archaean age, forms the axis, while on the flanks, dipping both east 

 and west away from the range, rest heavy rock masses of sandstone and 

 limestone of Palaeozoic age. 



These later beds, lying unconformably upon the older granites, are 

 seen way up on the sides of the range, at altitudes higher than the old crys- 

 talline bodies. Nowhere over the entire area of the Laramie Hills are there 

 any remnants or patches left standing of the Palaeozoic beds ; but there can 

 be but little doubt that they formerly passed over the top and formed con- 

 tinuous strata. On the west slope of the mountains the Palaeozoic beds pre- 

 sent a somewhat monotonous, uniform, unbroken body in a north and south 

 line, along the entire slope down to the Laramie Plains. The highest incli- 

 nation of the beds observed was 10° ; the lowest, 4°. 



Upon the east side the contrast is quite marked, and the diversity in 

 occurrence as striking as is the uniformity on the opposite side. The con- 

 tinuity of the strata is frequently broken, the beds occasionally not appearing 



