244 RECORD OF SCIENCE FOR 1887 AND 1888. 



alphabet was devised, aud iiow geologists read geologic history from the 

 hills as well as from the strata and their contained fossils. 



This line of investigation has been successfnlly pursued by Davis,* 

 who has acquired such skill in the interpretation of geologic history 

 from topogniphic forms as to be able to read the principal events in 

 the geologic development of New Jersey and Pennsylvania from topo- 

 graphic maps ; it has been pursued by McGee with such success that 

 " probably for the first time important i)rnctical conclusions, involving 

 the consideration of hypogeal structure and orogenic movement, have 

 been based on the interpretation of topography aud on inferences from 

 the present behavior of the streams by which the topograi)hy 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 Neiv Geolor/y. It opens a new field for the science 

 so extensiv^e as to nearly double its domain j 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- 

 sively 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 chielly 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, aud 

 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 afforded by the organization and 

 active work of the Congres Gt'ologique 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 

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

 subclassifications are designed to be thrown together into a general 

 taxonomic 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, IST. 13. Winchell; on the 



*Nat. Geog. Mag., vol. i, pp. 11-26. 



t7th Ann. Rep. U. S. Geol. Survey, 1888, pp. 547-548. 



