790 EXPERIMENT STATION RECORD. 



WATER— SOILS. 



The cienegas of southern California,' E. W. Hilgard [Califor- 

 nia Sta. Rpt. 1893 and 1894, pp. 185-188). — "A cienega, in tlie parlance 

 of the native Californian, is a limited area showing' a growth of water- 

 loving i^lants, appearing sporadically in otberwivse arid surroundings — 

 usually hillsides or valley margins — and occasionally giving rise to 

 flowing siiriugs." The cienegas of the San Antonio, Santa Ana, and 

 Mill creeks, and of the Teniescal Valley, are described and their value 

 as sources of water supply discussed. 



"While they do not i-eiuler the establishment of artifieial storage reservoirs snper- 

 fluoiis, they do supplement them locally to a very material extent, rendering it pos- 

 sible to occnpy for agriculture large areas that otlicrwise would have remained arid 

 for many years to come. 



"But there arises the question as to the geographical limits within which these 

 natural storage reservoirs may reasonably be sought, lor it is notorious that they are 

 not usually found, and the name and idea of the cienega is not generally known in 

 the northern portions of California. 



"The essential condition of cienega formation is manifestly the opportunity for 

 the abundant formation of deposits of exceptionally coarse and pervious gravel and 

 cobbles near the points where the canyons emerge from the mountains. This, again, 

 is necessarily conditioned upon the occasional occurrence of violent, torrential rain- 

 fall in the mountains, alternating with periods when quiet deposition allows of the 

 formation of water-shedding layers. Another condition appears to be the ready 

 weathering of the parent rocks into rounded forms, by which close packing is pre- 

 vented, so that abundant interspaces are permanently maintained. Both conditions 

 are fulfilled to an unusual extent in the granitic ranges of southern California." 



Investigations in soil physics, K. H. Lougheidge {California Sta. 

 Rpt. 1893 and 1894, pp. 70-100, dgms. 2). — The results of examinations of 

 a large number of different soils made at intervals during the past 15 

 years at the California Station are summarized in this article, "in order 

 to draw as far as possible some conclusions, either positive or negative, 

 as to the relation of the various sediments or ingredients to the i)ower 

 possessed by soils to absorb hygroscopic moisture, to their capacity for 

 holding water, and to their power of transmitting water by capillarity." 

 A somewhat detailed discussion is given of the influence of i)liysical 

 constitution and chemical composition of the soil on its liygroscopicity, 

 especial attention being given to the influence exerted by clay; the 

 methods and results of studies of the water-holding capacity of differ- 

 ent soils, and the rapidity, height, and extent of the cai)illary rise of 

 "water in soils of different character subjected to different treatment. 



The general conclusions drawn are as follows: 



"(1) The power possessed by soils of absorbing moisture from the atmosphere and 

 to hold water within their pores is not proportionate alone to the amount of com- 

 bined surface presented by the particles of the soil; and while, as a very general 

 class, soils with large percentages of clay and fine silts have a high moisture and 

 water capacity coefficient, such materials by no means control that power, simply 



1 Read at the meeting of the Geological Society of America at Washington, August, 

 1891. 



