ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded 'promptly to the editors. 

 Each of the scientific bureaus in Washington has a representative authorized to 

 forward such material to this Journal and abstracts of official publications 

 should be transmitted through the representative of the bureau in which they 

 originate. The abstracts should conform in length and general style to those 

 appearing in this issue. 



GEOLOGY. — Ground water in San Simoji Valley, Arizona and New 

 Mexico. A. T. Schwennesen. U. S. Geological Survey Water- 

 Supply Paper 425-A. Pp. 35, with maps. 1917. 



This is a preliminary report on an extensive investigation of the 

 Quaternary geology of the San Simon Valley and adjacent parts of 

 Gila Valley and its relation to artesian water supphes in the region. 

 The stream deposits, which resemble the ordinary deposits of other 

 desert basins, are here separated by beds that were laid down in a 

 lake or other body of water to a depth of several hundred feet. These 

 lake beds form a gentle syncline whose axis nearly coincides with the 

 axis of the valley. They include 300 to 400 feet of dense, homog- 

 eneous, blue clay, which serves well as a confining bed for the water 

 in the underlying sand strata and older alluvium. Extrusive basalt 

 is interbedded with the stream deposits and layers of tuff occur in the 

 lacustrine formation. 



The report gives data on artesian and pump wells, and on the de- 

 crease in artesian pressure. It includes an excellent discussion of 

 agricultural possibilities by R. H. Forbes. 0. E. ]\Ieinzer. 



GEOLOGY. — Ground water for irrigation in the Morgan Hill area, 

 California. W. O. Clark. U. S. Geological Survey Water- 

 Supply Paper 400-E. Pp. 48, with 3 plates. 1917. 

 The water-bearing formation in the area consists of recent alluvial 

 deposits which are composed of clay or claylike materials, sand, and 

 gravel. Most of the deposits were formed by Coyote River, which 

 has built an alluvial fan entirely across the valley and which has alter- 

 nately diverted the streams on it into the Bay of Montere}' and into 

 San Francisco Bay. 



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