NOTES ON THE GEOLOGY OF NOHTHEASTERN NEW MEXICO. 



By O. St. John. 



In the region of the headwaters of the Canadian is embraced a terri- 

 tory which, for the completeness of its geological record and the interest 

 of its concomitant topographical and scenic features, is not excelled 

 perhaps by a similar extent of country in the West. It is bounded on the 

 ■west by the Spanish range, which in this part of its course consists of a 

 densely-wooded watershed-divide, 9,000 to 11,000 feet in altitude, from 

 which at intervals lofty lateral spurs are thrown off, whose bald summits 

 overtop by 1,000 to "2,000 feet the actual watershed, which latter extends 

 in a general north-south direction. Near the Colorado line, the range is 

 intersected by the Eaton Mountains, a range of gladed hills extending 

 eastward forty or fifty miles, and constituting, with the still easterly 

 prolongation in the Chicorica Mesa, the northern limits of the district, 

 which opens out to the southeastward into the great plain. Thus defined, 

 the district comprises an area of about twenty-five hundred square miles. 



During the season of 1869, in the progress of his extended reconnais- 

 sance of the Eocky Mountains, Dr. Hayden visited this region, from 

 whom we have authentic account of its general geological features, 

 and their intimate relation to those prevailing in other and similar 

 districts to the north and south. A few months' residence in this part 

 of the country in 1874-'75* afforded the writer opportunity to become " 

 somewhat familiar with its geological features ; and the purpose of the 

 present communication is to present such facts as may tend to contribute 

 something toward a similar knowledge of remote and perhaps hitherto 

 rarely- visited, localities, and their connection with already-examined 

 districts. 



THE UPPEE BASIN OF THE CANADIAN. 



In the mountains along the western boundary of the district, many 

 little streams take their rise, which, flowing southeasterly across the 

 great Tertiary plateau, whose surface they score with rugged gorges 

 and beautiful little valleys, finally emerge into the upper basin of the 

 Canadian. This basin forms one of the peculiar and interesting features 

 of the region, and which deserves passing notice, as well on account of 

 its scenic surroundings as the important part it must eventually take 

 when the time arrives for utilizing its thousands- of acres of fertile irri- 

 gable lands. Among the most important of these tributaries are the 

 Vermejo and the Cimarron ; the aflluent which retains the designation 

 of the principal stream rising in the plateau, its drainage being entirely 

 derived from the Eaton ridge. A short distance below the mouth of the 



* It is with peculiar pleasure the writer seizes the opportunity to express his ac- 

 knowledgments to his friends Messrs. Frank Springer and W. R. Morley : to Mr. 

 Springer he owes the possibility of a pleasant sojourn of several mouths at Cimarron ; 

 •and to Mr. Morley he is indebted for valuable data, especially relating to the topography 

 and hypsometry of the country. 



No. 4 1 



