318 GEOI.OGICAL SURVEY OF THE TERRITOEIES, 



Part I —DETAILS OF EXPLORATIONS IN THE LIGNITIO FOR- 

 MATIONS OF THE ROOKY MOUNTAINS. 



Before arriving at Denver, on the line of the Kansas Pacific Railroad, 

 I had the opportunity of examining, at two different places, heaps of 

 lignitic coal taken out of abandoned and closed shafts. The lignite 

 appeared of very poor quality, had been taken from various depths, and 

 little evidence on the age of the strata could be obtained from the mixed 

 and mostly disintegrated materials scattered around near the mouth of 

 the shafts. West of Denver, at Golden, Marshall's, &c., I became more 

 intimately acquainted with the general features of the so-called western 

 Lignitic formation. Afterward, from Denver, my explorations were pur- 

 sued southward to Colorado Springs; then in the Arkansas Valley, and 

 from Oaiion City, along the base of the Rocky Mountains, to Trinidad 

 and the Raton Mountains, in New Mexico. As it is at this last-named 

 locality that I was for the first time able to see a well-exposed section 

 of the whole formation, to study, therefore, its essential characters and 

 the relative position of its more important members, Ij)ropose to begin, 

 at the Raton Mountains, the descriptive narration of my researches, to 

 pursue it hence northward to Denver and Cheyenne, and then along 

 the Union Pacific Railroad to Evanston, where the explorations were 

 discontinued. In following this plan some preliminary general conclu- 

 sions may betaken from the data ascertained at the beginning, and may 

 be used henceforth as points of comparison and reference for facts and 

 observations obtained elsewhere, and which may afford confirmation or 

 conflicting evidence. 



§ 1. Raton Mountains. 



The small town of Trinidad is pleasantly nestled on the south side 

 and in the bottoms of the Purgatory River, which here runs eastward, 

 to take farther east a more northerly course to the Arkansas River. 

 Behind the town a series of round, more and more elevated hills cover the 

 base of the highest peak of the Raton : Fisher's Peak, a dark basaltic or 

 volcanic mass, which towers above the country at an altitude of about 

 2,000 feet. Opposite Trinidad, on the south side of the river, appears 

 an extensive range of hills capped by thick, mostly perpendicular rocks 

 of sandstone, overlying black soft shale, which descend in steep slopes 

 to the plain. On the western side the Raton Creek, running north, 

 passes through the hills in a narrow, pleasant, green valley, entering 

 Purgatory River three miles above Trinidad. 



In passing obliquely from the town to the Raton Valley, in a north- 

 west direction, the stage-road gently ascends about 150 feet to a plateau 

 which at first is seen formed, even at its surface, of the black shale No. 

 4 of the Cretaceous,* which here contains well-preserved, large, charac- 

 teristic shells in ferruginous concretions. But soon the plain appears 

 cut by undulations, which already, one mile from Trinidad, have their 

 tops strewn with large broken flags of sandstone, over which no other 

 trace of fossil remains but marine plants or fucoids are seen. A little 

 farther from the town the same sandstone is in place, immediately and 

 conformably overlying the black shalej and in entering the small val- 

 ley of the Raton, the road curves around steep hills, whose base rests 



* The divisions of tlie Cretaceous indicated in this report are those of Messrs. Meek 

 and Haydeu, marked in the general section of this formation in Dr. Hayden's report, 

 1B70, page 87. 



