244 RECORD OF SCIENCE FOR 18X7 AND 1888. 



al[)lial)et was devised, and now geologists read geologic liistory from the 

 liills as Avell as from the strata and tbeir contained fossils. 



This line of investigation has been successfnlly i)ursued hy Davis,* 

 who has ac(]uired such skill in the interi)retalion of geologic history 

 from topographic forms as to ha able to read the principal events in 

 the geologic development of ]S"ew Jersey and Pennsylvania from topo- 

 grai)liic mai)S ; it bas been pursued by McGee with such success that 

 " probably for the first time important practical conclusions, involving 

 the consideration of hypogeal structure and orogenic movement, have 

 been based on the interpretation of topography and on inferences from 

 the present behavior of the streams by which the topography has been 

 determined ; " t and it has also been pursued with success by Willis in 

 the central Appalachian region. So complete has been the develop- 

 ment of this method of investigation that nearly as much information 

 concerning the geologic history of the Atlantic slope has been obtained 

 from the toi)ographic configuration of the region within two years as 

 was gathered from the sediments of the costal plain and their contained 

 fossils in two generations. 



The interpretation of geologic history from topographic configuration 

 may well be called the ISfew Geology. It opens a new field for the science 

 so extensive as to nearly double its domain ; and this field has been 

 fully entered by American geologists alone and within the last two 

 years. 



DEPOSITION. 



The clastic rocks — the products of deposition — have been more exten- 

 eively studied than any other class of geologic phenomena ; out of their 

 study has grown the greater part of geologic literature ; surveys and 

 commissions have been endowed chiefiy for the purpose of investigating 

 them ; national and international conventions have been established to 

 discuss them; and their relations to science in general, to the arts, and 

 to the welfare of the race have been elaborated by a host of students. 



During the biennial period special attention has been given to this 

 branch of geology under the stimulus afibrded by the organization and 

 active work of the Congres Geologique International abroad and the 

 American committee of the Congres in this country. The American com- 

 mittee operated mainly through subcommittees, consisting of a few spe- 

 cialists (one of whom was the reporter of the subcommittee) and some- 

 times associates. Each subcommittee sought to develop a taxonomy 

 apjdicable to a particular i)art of the geologic column, and the various 

 subclassifications are designed to be thrown together into a general 

 taxouomic system similar to but more refined than those current in 

 objective geology for a generation. The reporters were, on the Archean 

 Persifer Frazer; on the Lower Paleozoic, N. IJ. Winchell; on the 



* Nat. Gpoj?. Mag., vol. i, pp. 11-26. 



t7tli Ann. Rep. U. S. Gool. Survey, 1888, pp. 547-548. 



