GEOLOGICAL SURVEY OF THE TERRITORIES. 101 



The lower portions of the Tertiary period of the West seem to be ma- 

 rine in their character, as shown by an abundance of fossil remains of 

 the genus Ostrea; but the physical conditions do not seem to have 

 been favorable for the development of a great variety of marine life. 

 The impressions of deciduous leaves similar to those belonging to our 

 present fruit and forest trees are very numerous throughout the Tertiary 

 beds of marine character, and they may be found in almost all localities 

 where the character of the rocky beds is such as to favor their preser- 

 vation. The marine beds gradually pass up into those of purely fresh- 

 water character. 



All these facts are very important, inasmuch as they fulfill all the 

 conditions of the growth of the continent, showing clearly all the steps 

 of progress onward even to the present time. 



There is another point of interest connected with these modern de- 

 posits of the West. There seems to have been a vastly increased de- 

 position of sediments during both Cretaceous and Tertiary times in the 

 West. The sediments are greatly deficient in calcareous matter, and 

 show a vast preponderance of arenaceous material. I have estimated 

 the thickness of the Cretaceous beds, as shown west of the Laramie 

 Mountains, at 5,000 feet, and the Tertiary the same ; so that we ha,ve here 

 10,000 feet of rocks of comparatively modern date. 



The next important question is, can all this vast area be made useful for 

 agricultural or grazing purposes "? 



We have shown that the eastern slope of the mountains can be culti- 

 vated very successfully by irrigation, but west of the Laramie range the 

 elevation above the sea is greater, and the climate much more severe in 

 winter. Even at the Laramie Eiver the elevation above the tide- water 

 is 7,222 feet, nearly 3,000 feet higher than Salt Lake Valley, and more 

 than 1,000 feet above Cheyenne City, near the eastern base. 



The Laramie Plains are also surrounded by lofty ranges of mountains, 

 the tops of some of which are covered with perpetual snow. The sum- 

 mer, therefore, in these plains must always be short, and the winter 

 severe. It is believed, however, that east of the Medicine Bow River the 

 principal cereals, as wheat, buckwheat, oats, and barley, can be raised 

 successfully. Potatoes and turnips, of very good quality, have been 

 raised this year in the valley of Rock Creek, on sod ground, and with 

 very little irrigation. 



The following valuable notes were furnished me by Major- General 

 John Gibbon, United States Army, commanding Rocky Mountain de- 

 partment, with permission to copy them entire. General Gibbon has 

 given more attention to this subject than any other man in the Territory. 

 He has cultivated an extensive garden at the military post. Fort 

 Sanders, for two years past. 



Vegetables which can be raised in Laramie Plains : 



All seed should be planted as soon after 1st of May as possible. 



Potatoes. — Should be planted early in May, in rows three feet apart ; 

 thoroughly irrigated immediately after planting, and the ground be- 

 tween the rows frequently kept open with a cultivator. It would be 

 better to plow out the furrows; fill them with manure or straw, and 

 plant on that. 



Peas. — Very fine ; soak the seed before planting in rows three feet 

 apart, and cultivate as above. 



String heans. — The same. 



Radishes. — Very fine; sow either broadcast or in rows three feet 

 apart, thin, and then weed out to four inches apart. 



