GEOLOGICAL SURVEY OF THE TERRITORIES. 27 



portions lap on to the sides of the ridge in regular order, then for 

 about five miles they have been entirely swept away, revealing the 

 metamorphic rocks in places and the contact of the unchanged beds 

 with them. An immense deposit of debris covers the lower ridges at 

 the base and juts up against the sides of the ridge; the nearly vertical 

 edges of the fragmentary ridges project above the debris, as remnants 

 left after erosion. The debris or superficial drift is so great that it juts 

 up against the side of the ridge at least six hundred feet above the bed 

 of the Platte, concealing, to a great extent, the underlying forma- 

 tions. Still portions crop out occasionally, showing that they exist. The 

 ridges of cretaceous and lignite tertiary are very distinct in the plains, 

 inclining from the mountain at a small angle. Near the Platte, about 

 ten miles above the Muddy Creek, there is a considerable area covered 

 with light-gray sandstones, which have weathered into most unique 

 forms. They resemble the ruins of some old village, portions of the 

 stone walls with the chimneys remaining. One mass of rock we called 

 the " Blacksmith's Forge." The material is a fine gray sandstone, with 

 very irregular layers of deposition. No single lamina can be traced 

 continuously more than a few feet. The rock is also full of rusty, ferru- 

 ginous, hollow nodules. It has been weathered full of holes and caves, 

 Avhich give it a picturesque appearance. These afford fine places 

 of retreat for wild animals. The sandstone is so soft they have be<^n 

 enabled to extend the natural cavities at pleasure. When exam- 

 ined with a glass the sandstone shows small particles of quartz, with 

 a few grains of feldspar and mica, loosely held together. The dip of 

 all the tertiary beds is northeast 5° to 20°. A bed of lignite crops out 

 in many places. Near old Fort Casper the long benches that extend 

 down from the base of the ridge toward the Platte form a marked fea- 

 ture in the surface. They are composed of tertiary and cretaceous beds, 

 and the latter formation is better shown here than at any other point 

 north of the Chugwater. These benches are really table-lands, their 

 surface appearing even and smooth to the eye. Just above the bridge are 

 some high bluffs on the left bank of the Platte, composed of lower creta- 

 ceous clays, No. 2. On the summit of the hills, about four miles east of 

 the Bed Buttes, are some quite prominent ledges of yellow ferruginous 

 sandstone with Inoceramus and huge rusty concretions;, underneath 

 them are the black shaly clays of No. 2, with all the evidence of barren- 

 ness which they carry with them. There seeing to be an unusual ex- 

 posure of the cretaceous beds for about fifteen miles, and they jut up 

 close to the base of Casper Bidge. The beds incline from the ridge in 

 regular order, and follow its flexures. 



Our camp near the Bed Buttes was an interesting and instructive one. 

 We were located on a broad, grassy bottom of the Platte, in a sort of 

 amphitheater, with the rocky beds rising to a great elevation all around 

 us. The Bed Buttes are so called from the high ridges or groups of ridges 

 which are separated by the channel of the Platte. The basset edges of 

 the beds bear eastward toward our camp, and a layer of the brick-red 

 argillaceous shales is exposed. As we approached them from the east 

 in the afternoon, the rays of the setting sun greatly heightened their 

 color and brought them out in relief, so that we could readily see why 

 they have been such prominent landmarks and have so long attracted 

 the attention of the traveler. These buttes, taken together, may be 

 regarded as an irregular anticlinal, with one side formed of quite 

 lofty ridges, and the opposite side fragments of low ridges, which look 

 as though they had broken off of the edges of the opposite portiou 

 during the upheaval. The red beds are well exposed, with a thickness 



