PREFATORY NOTE 



Now that two numbers; of the Balletin have beeu issued by the Survey, 

 a word of explanation as to the object of its publication seems to be 

 necessary. The vast amount of new material in all departments of nat- 

 ural history collected in the West under the auspices of the Survey, 

 and in some instance demanding prompt publication, suggested the 

 present form, in order that this new matter might not be too much scat- 

 tered, either in the proceedings of societies, or in independent papers 

 not easily accessible to the scientific student. The annual report will 

 not appear until late in the summer, (July or August,) and, in consequence, 

 the Bulletin will be issued from time to time as the necessity arises for 

 the prompt publication of valuable matter. 



ThearticlebyProfessorCopeinthepresentnumberoftheBulletin isone 

 of no ordinary value. While I dissent from some of his views, I regard his 

 researches as having a direct bearing on the solution of the problem to 

 which I have repeatedly called the attention of geologists in my annual 

 reports as the most important one in the geology of the western portion of 

 our continent, viz: The relations of the Cretaceousand Tertiary periods to 

 each other. I have always expressed my belief in the continuity of all 

 the great formations from the Silurian to the present time, and that the 

 highest privilege of the geologist is to discover the evidence that bridges 

 over all chasms and obliterates all the lines of demarkation. When our 

 knowledge of the geological history of the world is more complete, we may 

 expect to find well-marked beds of passage or transition between all the 

 great groups of the geological scale. Hitherto, the chasm between the 

 Cretaceous and the Tertiary periods has been very marked ; but the evi- 

 dence now so rapidly accumulating points to the conclusion that this, too, 

 will be bridged over. The solution of this problem has also a most inti- 

 mate connection with the physical growth and history of the western por- 

 tion of our continent. One of the principal objects of the survey for years 

 has been, to collect all the evidence bearing on this subject that could 

 be secured, and, with this thought in view, I have requested Professors 

 Leidy and Cope to approach the problem through the extinct vertebrate 

 fauna, Mr. Lesquereux through the fossil flora, and Mr. F. B. Meek 

 through the study of the invertebrata. The differences of opinion as 

 to the age of the formations under discussion have been very great. 



Up to within a comparatively recent date I have regarded the entire Lig- 

 nitic group of the West as of Tertiary age. My own explorations began 

 at an early period (1853) in the Northwest, along the Missouri Kiver and 

 its tributaries. There, the Lignite group is largely developed, and is even 

 at this time supposed by some of our best geologists and paleontologists 

 to be of Middle Tertiary age. This group in the Northwest indicates a 

 brackish water deposit at the base, but is mostly of purely fresh-water 

 origin. I traced this group, without interruption, from latitude 49° north, 

 along the east base of the Rocky Mountains southward, to a point near 

 Laramie Peak, latitude 43°, where it is overlapped by the White River 

 deposits for a distance of about two hundred miles. The lignitic beds 

 rise again to the surface about fifteen miles south of the Union Pacific 

 Railroad. A very narrow range of mountains separates this group from 

 the Laramie Plains, and prior to the elevation of the mountains, no 

 doubt, the surface-continuity was unbroken. During the summer of 

 1868 I made a careful examination of the coal-beds at Bear River Sta- 

 tion and Coalville, Utah, and there I found the first proof that I had 



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