326 . GEOLOGICAL SURVEY OP THE TERRITOEIES. 



The sandstone over tlie Gebruug eoal, No. 4 of the section, is by its 

 appearance, its mode of weathering by effoliation, &c., the equivalent of 

 the lignitic fucoidal sandstone. On the south side of the river, where 

 the coal is opened, it does not contain fossil remains of any kind, and is 

 comparatively thin. Bat on the other side, its thickness increases to 

 about 75 feet, and it has some remains of fucoids, and a thin bedaf coal, 

 (6 inches,) a mere streak in the sandstone. In its upper part, this sand- 

 stone, ferruginous and shaly, contains a quantity of dicotyledonous 

 leaves, Fopulus, Platanus, &c., with large fragments of Sabal leaves, all 

 species which, by identity with some found at the Eaton and in the 

 Arkansas Valley, do not leave any doubt about the contemporaneity of 

 these Lignitic measures. 



By far the most interesting member of the section at Gehrung's is the 

 conglomerate formation at the top. These rocks are a compound of small 

 grains or pebbles, mostly of white quartz, and of silex of various colors, 

 varying in size, at least for the largest pro]iortion, from that of a pea to 

 that of the head of a pin. Pebbles as large as a walnut are still abun- 

 dant ; the largest, like the tirst, are rare, and especially found within the 

 layers of the top. This formation, 150 feet thick at least, is conforma- 

 ble to the strata overlying the coal of the base of the section, and here, 

 as it will be still seen at other places, it overlies immediately thick banks 

 of soft, laminated, bituminous, black clay. The materials forming this 

 conglomerate are cemented together by a thin coating of carbonate of 

 lime, which easily disaggregates under atmospheric influence, except in 

 the upper stratum, where the cement has been hardened by ferruginous in- 

 filtration. Its greater resistance has then locally preserved the whole mass 

 from destruction. These conglomerate clifls, which, from the hotel of 

 Colorado Springs, arrest the view to the west, appearing like high bluffs 

 of white sandstone, are evidently the mere vestiges of an extensive 

 formation, originally covering the base of the mountains from the 

 Arkansas River, extending far inland to the east. For hundreds of 

 miles the ground of Colorado Territory is formed by its debris. They 

 have given to the soil that apparent sterility of surface which is so 

 remarkably changed into fertility by the culture of the substratum com- 

 posed of softer-grained materials and lime. Nearer to and along the 

 base of the Colorado Pinery, whose Lignitic hills have escaped destruc- 

 tion by the upheaval of the ridge, these conglomerates, still detached 

 from the common mass, and molded into the most diversitied forms by 

 disintegration, have scattered columns, pinnacles, round towers, and 

 cupolas over a wide area, the far-lamed Monument Park. 



I have not had opportunity to examine the highest ridges of this 

 Colorado Pinery, whose southern base is about live miles from Colorado 

 Springs, and on the other side descends to five miles south of the South 

 Platte. Dr. F. V. Hayden, who has surveyed the formation, considers 

 it as Upper Miocene (f) (modern Tertiary deposits) comparing it to a group 

 of rocks which covers the country from Fort Bridger to Weber Caiion, 

 and also to a series of sands and sandstones along the Gallisteo Creek 

 below Saute Fe, the Gallisteo group.* We shall have opportuuitj'^ to 

 see this formation again, and to consider its age with more details. 

 Here, as at other localities, it is conformable to the Lignitic, which re- 

 appears on the northern side of the ridge, along Cherry Creek and other 

 branches emptying into the Platte. No beds of Lignite are as yet re- 

 ported along this slope; but the clay-beds have, as on the other side, an 

 abundance of silicified wood. I have seen many fine specimens of it in 



* Dr. F. V. Hayden's Report, 1869, p. 40. 



