100 GEOLOGICAL SURVEY OF THE TERRITORIES. 



if it had been wrought with a pluinb line. There are a few small grooves 

 or scratches, and by means of a compass I ascertained the direction to 

 be about 27° west of north, or about northeast and southwest. There 

 seem also to be two sets of scratches crossing each other at different 

 angles. 



It would appear, from the evidence we have, that all the limestones 

 underneath the yellow marl and pebble deposits around Omaha, and 

 south to the Platte River, were smoothed or planed off by immense 

 masses of ice passing over them, for wherever these superficial deposits 

 have been stripped, the upper rocky layers are planed off with remark- 

 able smoothness. In the mountains proper, the evidences of glacial 

 action are not uncommon, especially on the sides of the deep valleys and 

 gorges, but the causes were local and operated when the temperature of 

 the climate was much lower than it is at present. 



Westward from Omaha we wend our way among the rounded grassy 

 hills which rise in wave like undulations as far as the eye can reach in 

 every direction. The first glance at such a scene strikes the stranger 

 with astonishment at its wonderful beauty, but it soon becomes so mon- 

 otonous that any flat plain or rugged mountain is a relief. About thirty 

 miles to the westward the road passes out of the hills into the valley of 

 the Platte, and the journey westward is one gradual ascent to the moun- 

 tains, walled on either side by more or less abrupt hills or bluffs. Here 

 we may stop for a while to discuss some of the more important geologi- 

 cal features for the first one hundred miles of our route. The surface 

 deposits over this area possess no small degree of interest, both in an 

 economical as well as scientific point of view, but I have already suffi- 

 ciently explained their character. They seem, however, to occupy a 

 very large area in this portion of Nebraska, concealing almost entirely 

 the underlying or basis rocks. The geology, therefore, becomes some- 

 what obscure, and can be studied only at a few outcroppings, from point 

 to point. The principal exposures are along the Platte, where the river 

 has cut a wide and deep channel through the surface of the country. 

 The fact, however, that the strata are very nearly horizontal, that there 

 are no upheavals nor mountain elevations to disturb the original posi- 

 tions of the beds, aids us much in our investigations. We believe that 

 the whole of Douglas County is underlaid by the limestones of the upper 

 coal measures, with perhaps a moderate thickness of the rusty sand- 

 stones of the lower cretaceous or Dakota Group lying above them in the 

 western portion of the county. At the mouth of the Platte these coal- 

 measure limestones are very conspicuous, and supply the greater por- 

 tion of the building stones of this region. The dip, if any, is quite gen- 

 tle toward the northwest, and at the mouth of the Elkhorn River the 

 carboniferous limestones have passed beneath the water-level of the 

 Platte, not to be seen again until we arrive at the eastern margins of 

 the Rocky Mountains. Overlying these are the ferruginous sandstones 

 which contain the impressions of deciduous leaves. Near the mouth of 

 Elkhorn are some of the abrupt bluffs of this sandstone, and the soft, 

 yielding nature of the rock has enabled the Indian to record on it his 

 curious hieroglyphical history. 



Fig. 4 illustrates the sandstone bluffs as they occur on Little Blue 

 River in the southern portion of Nebraska. 



The question often arises in the minds of visitors to this region, how 

 the law of compensation supplies the want of fuel in the absence of trees 

 for that use. Many persons have taken the position that the Creator 

 never made such a vast country, with a soil of such wonderful fertility, 

 and rendered it so suitable for the abode of man, without storing in the 



