Glacial Geology in A)ncrica. — Fairchild. 165 
iod. He did not agriee with Agassiz's extreine' views of great 
southern extension of a polar ice-cap; and his moderate con- 
chisions are; in general, accepted to-day. ■ ■.: -.i-.; : 
At this opportune time, 1.867, when, the gxeatly stimulated 
thought of the people.. was turned into peaceful ways, the re- 
vised edition of Dana's Manual carried the glacial theory i iMo 
every college of the land as the evolutionary product '.of the 
discussion upon the drift during the fourth of areiitury.:Hio:W+ 
ever^ the theory stiJl found soiue opposition, and ast latetial 
1871 Dana said that Aiuerican geologists; were divided ofntj^e 
iceberg and glacial theories, and' he deemed, ii necessary t<5 
give further proofs against the formen. the 
When shall we say ' that glacial i geology had its. .beginning 
in America? ;The discussion of.'the theory began in 1841 with 
the address of Edward Hitchcock; c -Tire acceptance isfnitjh'e 
theory by any number of Americans!, could notrhave bepn\eki-* 
lier than the personal advocacyby Agassiz aTTd.G'uyot:'iia't'i81|8 
to 1850. In some: qualified form ftheiHeDcy lw.a's; doetbtiiaES 
adopted earlier by a few independerit thirrkersr,: as;Coniradi8^d 
iVanuxem. 'The general acceptance of the tiieory,.and(thieiitiak> 
ing'ofit a basis for. systematic. wo^k-'iaaii'deiinvEstlgatiiQttal aiai 
probably not before 1867.. - / t: -.?': cf the thicory v::x\ tlie mak- 
The periods in' the histoi^.'of .drift-studyiincAtrietica; may 
be stated as 'follows: ^ (/'. 
Undisputed reigiiiof idiluvial ' hypbthjasiisr- ito .■i82|L3]ica may 
h Discussion of' the glacial hypothesis — 1841 to 1848. 
Gradual adoption.' of i'the glacial ttreohy-i^i^Q tri3j(.866. 
Development of glacial geolog>r-^-e 18671 [irpidiatei 848. 
Centers' of L)isper!sio?i. -^T)^e tzrW ^\^^ of tlie unity and 
simplicity of the ice-cap,-' following -Agassiz's extravagant hy- 
pothesis of hemispheres of ice'. did::iibt lo-ng: enflfihe theittesiiuF 
advancing knowledge. --The dii-ectiDirrof iatriae::and:tliffrtriTnt4 
pf iperipheral moraines wer.e\S(6:o!n: crstogTiized-ae ti'nditialiiug 
complexity of growth arid' of ('movement ilii; rS^l ©ana-eaiirl 
giied for multiple centers of radial nim^merit,' ind he olt-iathejl 
the New England glacier' td' a eource:'b.etwteen: Ct^e StriiLaar- 
renc'e and Hudson bay. In. 1879 hcsaidLthereflidd befeirrnd) 
ice-cap involvingthe whole' polar region', amd rcc<D]gni^d,Iads\>. 
that an in'clination oF the lahd surf5iGei'wa9(hcii:.nex:essdrj')rfcai the 
.'•........, ::-■■;] ,-^ :;;;;■ i:c(I, alsj, 
. . :";cccrsarv for the 
