GEOLOGICAL SUKVEY OF THE TERRITOEIES. 123 



and a few shrubs in the immediate bottom, the level, lawn -like terraces 

 covered with a thick carpet of grass, and gradually ascending to the hills 

 on either side. The entire surface has been so perfectly softened down 

 by time that the beauty of the scene is perfect. It is true, the plains are 

 not at all times as uniformly smooth as this view would indicate. Not 

 unfrequently the surface is rugged in places ; masses of sandstone or 

 limestone with steep sides rising in the midst of the plains — monuments 

 left after the action of the waters that have smoothed down these beautiful 

 landscapes. It would seem that they are left to aid us in reconstructing 

 the geography of past geological times. 



Near the middle of these plains, on Cooper's Creek, are some quite re- 

 markable exhibitions of the chalk cliffs of the middle cretaceous period, in 

 which are oyster-shells, fish scales, and the bones of a huge Saurian rep- 

 tile. A little farther to the west is a long line of yellow sandstone bluffs 

 two hundred to three hundred feet high, forming beds of transition or pass- 

 age between the cretaceous and tertiary periods ; and still farther west are 

 more rugged hills in which are found beds of coal. We see, too, everywhere 

 indications of the action of water on the surface of the plains. In many 

 places rounded boulders of all sizes, from the minute pebble to a mass two 

 or three feet in diameter, are found scattered profusely over the ground. 

 Sometimes these rocks accumulate in vast quantities on the side of a hill, 

 literally paving it; then again in long lines or rows, as if they had been 

 carried* by swift water or dropped from an iceberg. Everywhere in the 

 vicinity of the mountains are abundant indications that the last act in 

 the drama was the existence of large bodies of water everywhere among 

 the mountains, which must have come from the mountains themselves, 

 inasmuch as the drift material indicates a local origin. We may suppose 

 that prior to the present period the temperature of the climate was very 

 much lower; that vast bodies of snow and ice accumulated in the mount- 

 ainous portions of our continent, and as the climate became more mild, 

 the ice and snow slowly melted, transporting icebergs filled with rocks all 

 over the plains, and when one of these vast icebergs would lodge and 

 melt, the accumulations of worn rocks and debris would be great. In 

 almost all cases the slope of the hill opposite the mountain range is the 

 one covered with the debris, as if the mass of ice in floating down passed 

 over the summit of the ridge and lodged on the opposite side. But it 

 would be impossible for us to linger in all these pleasant places; entire 

 volumes could be written illustrating the details of the geology of these 

 plains; our only object is to gather along our route such facts as will 

 illustrate our views and link our story together. 



Before we again start on our way westward, we ought to take a glance 

 at the North Park, which is only about fifty miles to the southwest of 

 Fort Sanders. The journey is quite easily made in two days, and even 

 in one day on horseback, which is by far the best method of traveling in 

 this mountainous region. In August, 1868, I made a tour to the North 

 Park with a small party of Army officers, and I shall not soon forget the 

 scene of beauty that was opened to my vision from the summits of the 

 mountains surrounding the park. I was the more desirous of visiting 

 this region because so little was known in regard to it, and, although my 

 visit was short and my examinations necessarily limited, I had the sat- 

 isfaction of giving to the world the first accurate knowledge ever obtained 

 by personal investigation of the geology of that interesting region. 



Our course from Fort Sanders was nearly southeast, up the Big Lara- 

 mie Biver, toward its source in the mountains. The geology of the plain 

 country through which the Big Laramie flows is very similar to that of 

 the Little Laramie, about fifteen miles to the westward. There are 



