dhabe, 
JOURNAL OF CEOLOGY 
APRII-MAY, 1902 
GEROLOGIC FORMATIONS VERSUS LITHOLOGIC 
INDIVIDUALS. 
A RECENT article in this JouRNAL by Bailey Willis, entitled 
oy 
“Individuals of Stratigraphic Classification, renews a discus- 
sion of both fundamental and practical questions coming before 
the geologist engaged in areal mapping, which has gone on 
since the earliest days of geology and seems destined to go on 
indefinitely. The writer recognizes that Mr. Willis voices the 
beliefs of many geologists, among them being Edwin C. Eckel, 
whose still more recent contribution to the discussion? indorses 
the statements by Mr. Willis. But there is another and funda- 
mentally different view of the matter, also held by many work- 
ing geologists, and the writer wishes to present a few remarks 
from that standpoint. It is desired particularly to discuss the 
proposition maintained by Mr. Willis that the proper carto- 
graphic units, representing ‘ Individuals of stratigraphic classi- 
fication,’ are ‘lithologic individuals,” discriminated by the 
geologist solely on lithologic characters. Mr. Willis cites the 
rules of the United States Geological Survey, established some 
twelve years ago, concerning cartographic units, upholding them 
in their most literal interpretation. But the writer does not 
*Jour. GEOL., Vol. IX, p. 557. 
2**The Formation as the Basis for Geologic Mapping,” Jour. GEOL., Vol. IX, 
p. 708. 
Vol. X, No. 3. 223 
