Mat 20, 1904.] 



SCIENCE. 



795 



The Cambrian is represented by 300 feet of 

 sandstone of Acadian or Saratogan age ex- 

 posed on the southeastern flank of the Frank- 

 lin Mountains. Two other areas of sandstone 

 of possible Cambrian age, but in which no 

 fossils were found, are in the southern Hueco 

 Mountains and northwest of Vanhorn. 



The Ordovician is represented by about 

 1,200 feet of limestone in the Franklin Moun- 

 tains. Three well-defined horizons are pres- 

 ent, the Calciferous, the Galena Trenton and 

 the Richmond. The Calciferous is also pres- 

 ent in the southern Hueco Mountains and 

 northwest of Vanhorn. A few isolated areas 

 of limestone of the Niagara division of the 

 Silurian occur in the Franklin Mountains. 



The Devonian system and the Mississippian 

 series of the Carboniferous are absent. The 

 Pennsylvanian is represented by two limestone 

 formations. The older occurs on the north- 

 western flank of the Franklin Mountains and 

 the younger covers a large area in the Hueco, 

 Diablo, Finlay and Cornudas mountains. 

 These formations are each several thousand 

 feet thick. In the Diablo Mountain region 

 there is evidence that the pre-Pennsylvanian 

 land was reduced to a peneplain. 



Over 4,000 feet of rocks of Permian age 

 containing a unique fauna which is being 

 studied by Dr. G. H. Girty are present in 

 the Delaware and Guadalupe Mountains. At 

 the base of the section are 200 feet of black 

 limestone. Above are over 2,000 feet of 

 sandstone and interbedded limestone which 

 are capped by 1,800 feet of massive white 

 magnesian limestone. The relation of the 

 Permian to the Pennsylvanian is concealed 

 by the intervening Salt Basin. 



A broad belt of gypsum, at least 300 feet 

 thick, overlies these rocks and the gypsum is 

 overlain by about 200 feet of sandstone and 

 limestone which outcrop in a low range of 

 hills west of the Pecos River. The age of 

 these rocks is not known. They are either 

 Permian or early Mesozoic. 



The Jurassic is represented by a small 

 limestone outlier of the Malone Mountains. 

 The relations of these rocks to adjacent 

 formations, however, is unknown, being con- 

 cealed by unconsolidated basin deposits. 



The Cretaceous is represented by the Fred- 

 ericksburg and Washita divisions of the 

 Comanche, which cover a considerable area. 

 The Fredericksburg has been divided into 

 three formations consisting of sandstone and 

 limestone aggregating about 1,500 feet in 

 thickness which are well exposed in the Finlay 

 Mountains, about Sierra Blanca and in the 

 southern Diablo Plateau. The Washita has 

 not been subdivided. It consists of about 

 200 feet of buff-colored limestone and cal- 

 careous sandstone and shale well exposed near 

 San Martine and Kent, and is present also 

 in small outlying areas in the Sierra Blanca, 

 Black and the Cornudas Mountains and in 

 the vicinity of El Paso. There is evidence 

 of the northward progress of the Comanche 

 Sea in this area, shown by Washita rocks 

 lying on the Carboniferous in the northern 

 ■part of the area, while farther south rocks of 

 Fredericksburg age immediately overlie the 

 Carboniferous. 



The Hueco, Salt and Toyah Basins — desert 

 wash-covered areas characteristic of the Trans- 

 Pecos country — are capped by unconsolidated 

 detritus of Pleistocene age. Deep wells show 

 that this material extends to considerable 

 depths, and though no fossils have been found, 

 possibly the lower deposits are of Tertiary age. 



Mr. A. C. Veatch then discussed ' Some 

 Peculiar Artesian Conditions on Long Island, 

 N. T.' 



On Long Island, while the principles which 

 govern artesian flows are necessarily those 

 which produce the same phenomena elsewhere, 

 there are certain essential modifications in the 

 nature of the factors which produce these 

 results. They may be briefly summarized as 

 f oUows : 



1. The deep zone of flow and the surface 

 zone are essentially continuous. The whole 

 island is composed of sands, with discontinu- 

 ous clay masses, and the rain water is free to 

 penetrate to any part of these beds without 

 regard to dip. 



2. The head depends not on dip of the 

 strata, but on the curved nature of the ground 

 water table, which gives to the water under a 

 clay bed a pressure equal to the height of the 



