8 iNTRODtTCTtON. 



The present report shows how nearly the facts were represented by this 

 map made by Prof. LeConte years previous to the present investigation. 



In the spring of 1887, while the law creating a geological survey was 

 before the Legislature, Profs. W. F. Cummins and R. T. Hill addressed 

 that body on the subject of geology. In his address, Prof. Cummins 

 made the statement, as the result of his investigations, that the Llano 

 Estacado was the site of a fresh water lake in Quaternary times. 



During the next year, Prof. Hill crossed the State in two railroad trips, 

 one via the Texas and Pacific, in company with Prof. Cummins, west- 

 ward bj" Pecos City, passing over the southern part of the Plains; 

 the other to Tucumcari, crossing the northern border of the Plains. 

 In an article entitled "Notes on the Geology of Western Texas," 

 published in the Geological and Scientific Bulletin for October, 1888, im- 

 mediately after his return from the West, he says: 



" The surface of the Llano Estacado is an early Quaternary loam, and 

 a direct continuation of the great plains of Kansas and Nebraska." 



Similar statements were made by him in other papers, but in none of 

 them was there any reason given for thus referring the deposits which 

 was more conclusive than those already offered by Shumard, Blake, Hall 

 and Lesley, Marsh, Le Conte, and Cummins before him. 



It will be observed that all of the statements, except that of Mr. Mar- 

 cou, while agreeing upon the fact of the presence of Tertiary or Quater- 

 nary deposits in the Llano Estacado, are simply based upon the lithologic 

 character of the materials, and in no case was any positive paleontologic 

 evidence brought forward to substantiate the assertions. 



The actual determination of the age of these deposits is the result of 

 the work of this Survey. 



In the winter of 1889-90 Prof. Cummins, while making his section 

 across the Permian to the top of the Llano Estacado, found the first fos- 

 sils in the plains material at Blanco Canyon, Crosby county. The beds 

 were briefly described in his paper, "The Permian of Texas and Its 

 Overlying Beds," in our First Annual Report (1889) under the name of 

 "Blanco Canyon Beds" (p. 190), and stated to be later than the Creta- 

 ceous. 



In the same Report the beds are referred provisionally (on account of 

 lithological resemblance and diatomaceous earth) to the same horizon 



