226 abstracts: hydrology 



HYDROLOGY. — Geology and water resources of a portion of south- 

 central Washi7igton. Gerald A. Waring. U. S. Geological Sur- 

 vey Water-Supply Paper No. 316. Pp. 46, 1 pi. 1913. 



Two geologic formations are exposed in the region here discussed: 

 Yakima basalt, of Miocene age, and the Ellensburg Lake deposits, also 

 Miocene, which are deposited directly on the basalt. Over a consider- 

 able area these formations are obscured by wind-borne material. Glacial 

 erratics occur sparingly. 



The main surface features conform to the structure, broad ridges 

 and wide plains and valleys being the dominant topographic forms. 

 The ridges resemble basin ranges but are unsymmetrical anticlines 

 rather than faulted blocks. Faulting has, however, produced the steeper 

 slopes. 



Stream gorges that cut directly across ridges appear to have been 

 formed by the slow uplift of the ridges across the established stream 

 courses. 0. E. Meinzer. 



HYDROLOGY. — The effects of ice on stream flow. William Glenn 

 HoYT. U. S. Geological Survey Water Supply Paper No. 337. 

 Pp. 77, with plates and views. 1913. 

 The quantity and distribution of winter stream flow are the result 

 of the combination of factors that may be classified as climatic, geologic, 

 topographic and vegetational. The climatic factors are precipitation, 

 temperature, barometric pressure and winds; the geologic factors in- 

 clude surface and underground rock structure; the topographic factors 

 include relief and slope which determine the character and amount of 

 natural storage, the location, size and trend of the drainage basin, and 

 the character of the streams and their tributaries; the vegetational fac- 

 tors comprise not only forestation, but the effects of all plant growth 

 and cultivation. A fifth factor is the result of artificial control of the 

 streams for water supply or power. 



The determination of stream flow during open water periods is based 

 upon a relation between stage and discharge which is determined by 

 measurements. During periods of low temperature, surface ice, frazil 

 and slush ice, and anchor ice, alone or in combination, will be formed. 

 The presence of ice in any of the above forms on the river tends to raise 

 the stage without a corresponding increase in flow. The presence of 

 ice is due primarily to low temperature, so that in order to determine 

 the stream flow during the winter it is necessary to make a study of 

 temperature, ice formation and gage height in connection with discharge 

 measurements. The temperature is also the largest factor in determin- 



