GEOLOGICAL SURVEY OF THE TERRITORIES. 161 



sides covered with masses of roiigli basalt, so much so as to render travel- 

 ing difficult aud very laborious. But inside of this crater there is 

 scarcely a rock to be seen, and the slightly concave surface is thickly 

 grassed over. The immediate sides of this mountain all around are covered 

 with longitudinal ridges of the rock which was evidently i)oured out of 

 the crater and ran down the sides. The circular crater is about fifty 

 vards in diameter, and is now filled up with earth. This rounded moun- 

 tain must have been built up by the continued overflow of melted rock, 

 and at this time its summit is at least twelve hundred to fifteen hundred 

 feet above Fort Union. In the vicinity are what seemed to be rifts, 

 which have now formed valleys or gulches, and on each side of which 

 are thick borders or walls of the basalt. 



About fifteen miles north of Fort Union there is another of these cra- 

 ters which has attracted attention. The depression is about two hun- 

 dred and fifty feet deep and five hundred yards in diameter, aud the rim 

 is broken away on the north side. The borders of the crater are elevated 

 about twelve hundred feet above the fort. This vast mountain mass 

 must be the accumulation of the outpoured melted rocks. All over the 

 sides are immense ridges or banks, as it were, of the nielted rock which 

 has flowed out of the crater. The summit is covered with lava, some of it 

 black and some of it of a red color, but very porous and light, like pumice, 

 so that the wind has distributed great quantities for a long distance over 

 the plains below. This melted material has been iDoured out over the cre- 

 taceous beds, often concealing them over large areas. I am convinced that 

 at one period a very large portion of this country was covered with these cra- 

 ters, but none of them seem now to be so well defined as those described. 



About four miles north of the fort is a mesa capped with basalt, which 

 is underlaid by cretaceous rocks. Sometimes the basalt is worn away 

 over large areas, uncovering the rocks below. The mesa is about three 

 hundred feet above the fort. The valley in which Fort Union is located 

 is a very beautiful one, aud is plainly carved out of the cretaceous 

 plateau. On the west side the abrupt walls can be seen for miles, but on 

 the east the ascent up to the foot of the tertiary mouutains is gradual,, 

 though here and there the cretaceous rocks crop out. 



Before closing this chapter I wish to offer my most cordial thanks to 

 the officers of Fort Union, for courtesies and aid which enabled me to 

 perform the work of a month in a few days. Under the intelligent 

 guidance of Captain W. E. Shoemaker, I spent two most profitable days 

 examining the country in the vicinity of Fort Union, and with Dr. D. C. 

 Peters, United States Army, visited the beautiful Mora Valley. The 

 entire party were the recipients of favors at this post, which showed 

 more clearly than I can express it in words the deep interest which the 

 officers of the army everywhere take in the development of the material 

 interests of that portion of the West where they are stationed. We could, 

 also measure the amount of life in the citizens of any town we visited, by 

 the interest they took in our efforts to study the resources of the country. 

 Mr. C. W. Kitchen, especially, and the citizens of Las Vegas generally, 

 extended every attention to us in their power, and I am convinced that 

 at no distant day th]s must be the most pleasant and jirosperous town in, 

 New Mexico. 



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