THE ROSWELL ARTESIAN BASIN. 



DATA CONCERNING A VALUABLE ARTESIAN 

 BASIN IN THE PECOS VALLEY IN NEW MEXICO. 



AN investigation of this important the north the thickness of the forma- 



artesian basin has just been com- tion has been greatly reduced by ero- 



pleted by Mr. C. A. Fisher, a geologist sion, especially in the vicinity of Ros- 



of the U. S. Geological Survey. His well, where it scarcely exceeds 100 feet, 



report, giving a large amount of inter- The underlying massive limestones 



esting'and valuable data, will be issued reach a very great thickness in this 



by the Survey in the near future. general region, but it is only the upper- 



Location. The Roswell artesian basin most member, a porous, sandy lime- 

 is located in the Pecos Valley, in south- stone, with which we have to deal in 

 eastern New Mexico. It occupies an the present consideration, 

 area varying from 6 to 8 miles in width, Distinct Horizons. There are four or 

 and extending from a point a few miles more distinct artesian water horizons 

 north of Roswell, New Mexico, to near occurring in the Permian beds of the 

 the mouth of Seven River, a distance Roswell basin. Three of them are 

 of about 60 miles. The greater part of found in the lower part of the red 

 this area lies along the west side of sandy series, while the fourth and 

 Pecos River, the surface rising very strongest flow is in the porous sandy 

 gradually toward White and Sacra- limestone. 



mento mountains. The eastern limits Source of Supply. These water-bear- 



of the basin are determined by moder- ing formations outcrop in successive 



ately high bluffs, which follow the gen- zones on the slopes to the west, where 



eral course of the river throughout the they receive their water supply by di- 



entire length of the basin. The west- rect absorption from rainfall and the 



ern margin is not indicated by any sinking of streams. The Hondo, Felix, 



topographic feature, but flows are ob- and Penasco are the most important 



tained on the gradual slope to an alti- sources of supply in this area. These 



tude equal to that of North Spring streams all rise high on the slopes of 



Lake, the apparent head of the Roswell the El Capitan, White, and Sacramento 



artesian waters. mountains, where the annual rainfall is 



Character of Rocks. The rocks of the relatively large. As a result they carry 

 district comprise limestone, sandstone, an abundance of water in their upper 

 clays, and gypsum, which are believed courses, all of which sinks in the out- 

 to be of the Permian age. Overlying crop zone of the porous sand}' lime- 

 these deposits are extensive sheets of stone and the overlying sandy series, 

 sand, gravel, and clay, laid down in and passes underground to the eastward, 

 successive terraces between the river After the water has entered these porous 

 and the high limestone slopes to the formations it is held down by impervi- 

 west. For convenience the Permian ous layers of limestone and clays, and 

 beds may be divided into three groups, under the lower lands eastward it is 

 the upper gypsum beds forming high under considerable pressure, 

 bluffs on the east, the red sandy series Depth. The flowing wells of this 

 which underlie the valley, and the mass- district vary from 50 to 800 feet in depth, 

 ive limestones comprising the rugged the shallowest ones occurring in the 

 slopes to the west. The beds have a uni- low valley lands east of Roswell. To 

 form dip of about 4 degrees to the east- the south this main flow is reached at 

 ward. The gypsum series has an aver- a much greater depth, due to the pres- 

 age thickness of about 300 feet, while ence of beds belonging to the upper 

 the red sandy series immediately under- part of the red sandy series. In sink- 

 neath reaches a thickness of about 600 ing an artesian well in the town of Ros- 

 feet in the south end of the basin. To well it is necessary to pass through 



(373) 



