224 abstracts: geology 



tion for calibrating the radiometer which includes the galvanometer 

 and the thermopile. 



Various widths and thicknesses of metal were used in the receiver 

 which was covered with various kinds of absorbing surfaces of lamp 

 black and platinum black. The instrument was found satisfactory 

 for refined radiometric measurements. 



The second paper gives the results of an inquiry into the probable 

 value of the coefficient of total radiation of a uniformly heated en- 

 closure or so-called black body. Experimental data are given on the 

 lack of blackness of the radiator, on the absorption caused by atmos- 

 pheric water vapor, on the reflecting power of lamp black, etc. 



W. W. C. 



GEOLOGY. — Ground water in Lasalle and McMullen counties, Texas. 

 Alexander Deussen and R. B. Dole. U. S. Geological Survey 

 Water-Supply Paper No. 375-G, pp. 142-181, with geologic and 

 artesian water maps and sections. 1916. 

 Lasalle and McMullen counties lie in the Coastal Plain of south- 

 west Texas, where irrigation supplies are valuable. Physiographically 

 they consist of uplands and valleys, the uplands being divided into 

 several parallel belts trending northeast, the valley lands including 

 two groups of Pleistocene terraces. On the uplands are remnants of a 

 late Pliocene plain now nearly destroyed by erosion. The sediments 

 exposed comprise several formations belonging to two systems, the 

 Tertiary and the Quaternary. Deep wells encounter also formations 

 belonging to the underlying Cretaceous system. The beds older than 

 the Quaternary have been elevated and tilted toward the Gulf. The 

 upland gravels and valley deposits were laid down after some tilting 

 and erosion had taken place. An important feature is a difference in 

 the direction in which the formations dip on the opposite sides of a line 

 extending diagonally across the area from the northwest corner of 

 Lasalle County, as suggested by the structure contours. A normal 

 fault having a vertical displacement of probably 40 feet is inferred on 

 the evidence of well sections and the quality of the water. There are 

 several extensive sandy beds separated by beds of impervious clay or 

 shale. The sandy beds are artesian reservoirs and supply flowing- 

 wells. Numerous analyses given in the report indicate that almost all 

 the waters exceed 500 parts per million in total mineral content, and 

 nearly two-thirds of them exceed 2000 parts. Sulphate and chloride 

 waters predominate and more than half contain notable amounts of 



