GEOTHERMAL DATA OP THE UNITED STATES 677 



form in different parts of the same flexure and illustrate the difficulty in inter- 

 preting underground structure from surface observations. Rock texture is an 

 important factor in influencing the minor crenulations. In this connection 

 some account was given of the construction of the structure map, especially in 

 areas where the coal has not yet been mined. 



GEOTHERMAL DATA OF THE UNITED STATES 

 BY N. H. DABTON 



(Abstract) 



This contribution consists of all available records of underground tempera- 

 tures in the United States. Some of the data are compiled, but there are also 

 presented results of observations by the author and his associates with a 

 special type of thermometer in deep borings and mines. Temperatures of many 

 artesian flows are included in the list. Some of the geologic relations of the 

 thermal gradients in certain districts are described and their probable cause 

 considered. 



MAGNITUDE OF CONTINENTAL DEPOSITS l 

 BY CHABLES B. KEYES 



(Abstract) 



With the constantly and rapidly growing appreciation of the importance of 

 those sediments now widely known as continental deposits, the establishment 

 of critical criteria for their discrimination has not kept pace. Certain of these 

 criteria need especial emphasis. In the genetic determination of some of the 

 more recently formed terranes, such as are found on the American continent 

 west of the Mississippi River, physiographic criteria are most useful. 



Of continental deposits those strictly fluviatile in origin are probably of far 

 less importance than has been supposed. Those of eolic nature appear to be 

 much more widely distributed and greater in extent than usually ascribed. 

 Wind-blown materials which come finally to rest in the ocean seem to consti- 

 tute a very considerable proportion of the sediments of all geologic ages that 

 are now commonly regarded as essentially marine beds. Some Paleozoic for- 

 mations lately considered as eolic in character are believed not to be such. 



When carefully evaluated, it may prove that fully one-half of all known 

 geologic formations belong to the continental mass of deposits. 



GLACIAL CIRQUES NEAR MOUNT WASHINGTON 

 BY JAMES WALTEB GOLDTHWAIT 



(Abstract) 



Several of the "ravines," "gulfs," or "basins" on the flanks of Mount Wash- 

 ington and neighboring summits of the White Mountains have distinct cirque 

 form. They lie on all sides of the range, and can not be explained as products 

 of glaciation by the ice-sheet which covered the summits. They seem surely to 

 have been carved out by local glaciers of the Alpine type. 



1 Read by title December 28, 1912. 



