1893.] NATURAL SCIENCES OF PHILADELPHIA. 313 



NOTES ON THE PHYSICAL GEOGRAPHY OF TEXAS. 



By Ralph S. Tarr. 



Preface. 



This paper is based in part upon personal observation, in part 

 upon the published results of others. 1 Free use has been made of 

 the results of the several geologists who have studied the Texas 

 region, and in most cases direct reference has been made to the 

 sources of information. I am particularly indebted to the publica- 

 tions of Prof. R. T. Hill for many geological facts and interpretations, 

 chiefly in the Cretaceous regions where this author has done so much 

 valuable work. With few exceptions, however, the work done by 

 others has been geological rather than physiographic, and con- 

 sequently I have been in many cases forced to rely upon my own 

 observations alone. Since these were made in sections only, it has 

 not been possible in all cases to make the results as definite as 

 could be desired. My observations were made in 1889 and 1890, 

 the time occupied in field work being almost eight months, the 

 larger part of which was spent in the Central Denuded Area. 

 Aside from this and short excursions and railroad journeys, I also 

 made a wagon journey across the State of Texas from north of 

 Austin to the Guadalupe Mountains in the Trans-Pecos region, and 

 spent several weeks in and about these mountains. 



The results embodied herein must therefore be understood to be 

 the results of reconnoissance, — preliminary exploration of a great 

 and interesting field. Were it possible that in the future I should 

 again have the opportunity of studying the region I would delay 

 the publication of this still longer; but this seems to be entirely 

 out of the question, and I believe that I am justified in placing the 

 results of my study on record to serve as a possible basis for future 

 work. 



Part I. — General Description. 



1. — General Geography. 2 

 (a) Topography. — The State of Texas consists, in the portion 

 which lies east of the Pecos river, of a series of plains, and west of 



1 The appended bibliography is a partial list of works consulted. 



2 1 shall follow in general the classification offered by Prof. R. T. Hill, (Am. 

 Geol., V, 1890, pp. 9-29,) since this is the only classification offered, and is both 

 natural and accurate. 



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