242 COMPTE-RENDU. — QUATRIÈME PARTIE 
Bay of Biscay. These observations show that witliin very late 
geolog-ic tirae probably ainiost tlie entire Atlantic sidc of the 
eastern continent bas bcen greatly iipliftcd, attaining as high an 
altitude as that which A. C. Ramsay and James Geikie |conjec- 
tured as a possible cause of the frost-riven liinestone-agglomc- 
rates of Gibraltar^. 
The early part of the Ouaternary era, and the glacial period 
into which its epeirogenic and climatic changes enhninated^ 
hâve been exceptionally characterized by many great oscillations 
of continental and insular land areas. Where movements of 
land élévation hâve taken place in high latitudes, either north 
or South, which rcceived abundant précipitation of moisture, 
ice-sheets were formed, and the weight of these ice-sheets, as 
was first pointed out by Jamieson, seeins to hâve been a chief 
cause, and often probably the only cause, of the subsidence ot 
these lands and the disappearance of their ice. But the original 
sources of the energy displayed in the earth movements of up- 
lift preceding glaciation, and why this lias been so extensively 
developed during the Quaternary era, are very difficult ques- 
tions, which it is not the purpose of this paper to consider, 
since I hâve attempted elsewhere to answer them, in an appen- 
dix to Wright’s/ce Age in North America. It may be properly 
noted, however, that the explanations mentioned are entirely 
consistent with Dana’s teaching that the great continental and 
oceanic areas hâve been mainly permanent from very early géo- 
logie times. 
Against this view that the accumulation of the Pleistoceiie 
ice-sheets was preceded and causcd by epeirogenic élévation, a» 
objection lias been urged which deserves careful attention. R 
consists in an approximate identity of level with that of to-day 
having been held by many drift-bcaring areas at a time very 
shortly preceding the glaciation. This is clcarly known to hâve 
been true of Great Britain and of New England. Near Boston, toi’ 
cxample, my observations of fragments of marine shells in the 
till of drumlins in or adjoining the harbour prove for that tract 
a preglacial height closely the saine as now at so late a tinic 
that the molluscan fauna, of which we hâve a considérable re- 
présentation, comprised only species now living. In respect to 
’ Quart. Journ. Geol. Soc., London, vol. XXXIV, 1878, p. fi0.5-S41. 
