lxxxiv REPORTS OF GEOLOGISTS. 



in co-operation with your Survey, which brought with it a small remunera- 

 tion for my services, which had previously been entirely voluntary. 



The extent and character of the region to be surveyed, as set forth more 

 fully in the accompanying paper, embraced an area of over 72,512 square 

 miles, or over one-fourth (27.75 per cent) of the total area of the State — a 

 region three times as large as the combined area of Massachusetts and Con- 

 necticutt, Rhode Island, New Jersey, and Delaware, or three times the size of 

 West Virginia. Since it would have been a physical impossibility for the 

 whole force employed upon your Survey to have covered this enormous area 

 with even a reconnoissance, it became a matter of necessity that the region 

 should be divided into working districts, and the work of my assistants lim- 

 ited to some certain portion. 



In accordance with the necessity, the total area was subdivided, therefore, 

 into the following artificial divisions for working convenience: 



1. Northern District, or portion north of the Colorado, including 24,000 

 square miles. 



2. Southern District, or portion south of the Colorado, including 48,000 

 square miles. 



3. Isolated areas, including remnantal patches surrounding the buttes of 

 Northwest Texas, or preserved in the mountain disturbances west of the 

 Pecos, or exposed in the Tertiary areas of East Texas by denudation. Area 

 not estimated. 



The Northern District was chosen as the best adapted for preliminary 

 operations, and the work has been confined to that field. 



Unlike most districts of the State, this region has been thoroughly recon- 

 noitered by previous investigations, and hence it was resolved to make what- 

 soever work was undertaken of a complete and final character. 



GEOGRAPHIC AND TOPOGRAPHIC WORK. 



The absence of good geographic and topographic maps has been seriously 

 felt, except in the small portion of the district covered by the United States 

 work, but it has been impossible to devote time to the correction of these de- 

 ficiencies, although some valuable data has been necessarily collected under 

 this head. 



STRATIGRAPHIC WORK. 



Since all geologic products of economic value are derived from the rocks 

 composing the strata, considerable work has been devoted to the ascertain- 

 ment of the stratigraphic conditions of the region, part of which has been of 

 the character of reconnoissance to ascertain and define the sequence of the 

 rock sheets and a part to the making of carefully measured and delineated 



