BIBLIOGBAPHY. 17 



In 1897 appeared a number of minor articles b}' Lakes, Draper, Rickard, and 

 others. Some of these are included in the bibliographjr, but require no special dis- 

 cussion. The Pueblo folio, bj^ G. K. Gilbert, which was published the same year, 

 receives consideration in connection with the Pikes Peak and Walsenburg folios in 

 the resume. 



The Aspen monograph, b}^ Spurr, with an introduction by S. F. Emmons, and the 

 Tenmile folio, b}' Emmons, which were published in 1898, are two works of detailed 

 and monographic character, such as have established sections at a number of points 

 through the State, serving as convenient standards of comparison with each other 

 and with works which have more of the character of reconnaissance. To these it 

 will he necessary frequently to refer. 



The same is trije of the Walsenburg folio, bj' Hills, and the Geology of the Rico 

 Mountains, bv Cross and Spencer, which appeared in 1900. 1 have hesitated to 

 include in the bibliography two papers by A. C. Spencer and myself, which were 

 published this year. They deal with the Ouraj' limestone and its Devonian fauna, 

 and their connection with the present subject consists in the fact that this formation 

 and fauna were for a longtime considered of Carboniferous age; that the Ouray lime- 

 stone does, locally at least, contain a Mi.ssissippian fauna in its upper part, though this 

 was not known at the time these papers were written; and that I erroneously referred 

 two specimens of this Mississippian fuana to the Devonian. I shall have occasion 

 several times to refer to these facts, but it will not be necessary to give special dis- 

 cussion to the papers themselves. 



In 1901 N. H. Darton read a paper before the Geological Societj" of America 

 upon a comparison of the stratigraphy of the Black Hills with that of the Front 

 Range of the Rocky Mountains. This paper was never published in full, but iden- 

 tical abstracts of it appeared in the bulletins of the society and in Science. No detail 

 is naturally expected from this paper, but some interesting comparisons and corre- 

 lations are made between the Front Range section and that of the Black Hills. I 

 will briefly discuss this paper at a later point. Elmer S. Riggs the same year 

 described the Dinosaur beds of the Grand River Valley in southwestern Colorado. 

 To this paper also I shall somewhat briefly refer later on. 



In 1903 only two papers have come to hand dealing directly with the Paleozoics 

 of Colorado. Both are l\v AV. T. Lee. In one of them he describes the areal 

 geology of the Castle Rock region. This paper is of interest because it describes 

 one of the rare occurrences of well-defined Paleozoic strata along the eastei'n 

 margin of the Front Range in Colorado, and I shall make special reference to it in 

 my resume of geologic literature. In the other he speaks of the Carboniferous 

 l)eds of the Sangre de Cristo Range, and to this, too, I will give further consideration. 



143(;i— No. 16—03 2 



