474 Reports and Proceedings—British Association— 
serves to show the direction in which we must look for further 
advances in this department of inquiry. 
During the last twenty years the evidence of inter-Glacial conditions 
both in EHurope and America has so increased that geologists generally 
no longer doubt that the Pleistocene period was characterized by 
great changes of climate. The occurrence at many different localities 
on the Continent of beds of lignite and fresh-water alluvia, contain- 
ing remains of Pleistocene mammalia, intercalated between separate 
and distinct Boulder-clays, has left us no alternative. The inter- 
Glacial beds of the Alpine lands of Central Europe are paralleled by 
similar deposits in Britain, Scandinavia, Germany, and France. But 
opinions differ as to the number of Glacial and inter-Glacial epochs 
—many holding that we have evidence of only two cold stages and 
one general inter-Glacial stage. This, as I have said, is the view 
entertained by most geologists who are at work on the Glacial 
accumulations of Scandinavia and North Germany. On the other 
hand, Dr. Penck and others, from a study of the drifts of the German 
Alpine lands, believe that they have met with evidence of three dis- 
tinct epochs of glaciation, and two epochs of inter-Glacial conditions. 
In France, while some observers are of opinion that there have been 
only two epochs of general glaciation, others, as, for example, M. 
Tardy, find what they consider to be evidence of several such epochs. 
Others again, as M. Falsan, do not believe in the existence of any 
inter-Glacial stages, although they readily admit that there were great 
advances and retreats of the ice during the Glacial period. M. 
Falsan, in short, believes in oscillations, but is of opinion that these 
were not so extensive as others have maintained. It is, therefore, 
simply a question of degree, and whether we speak of oscillations 
or of epochs, we must needs admit the fact that throughout all the 
glaciated tracts of Kurope, fossiliferous deposits occur intercalated 
among glacial accumulations. ‘The successive advance and retreat 
of the ice, therefore, was not a local phenomenon, but characterized 
all the glaciated areas. And the evidence shows that the oscillations 
referred to were on a gigantic scale. 
The relation borne to the glacial accumulations by the old river 
alluvia which contains relics of Paleolithic man early attracted 
attention. From the fact that these alluvia in some places overlie 
glacial deposits, the general opinion (still held by some) was that 
Paleolithic man must needs be of post-Glacial age. But since we 
have learned that all Boulder-clay does not belong to one and the 
same geological horizon—that, in short, there have been at least two, 
and probably more, epochs of glaciation—it is obvious that the mere 
occurrence of glacial deposits under Paleolithic gravels does not 
‘prove these latter to be post-Glacial. All that we are entitled in 
such a case to say is simply that the implement-bearing beds are 
younger than the glacial accumulations upon which they rest. Their 
horizon must be determined by first ascertaining the relative position 
in the Glacial series of the underlying deposits. Now, it is a 
remarkable fact that the Boulder-clays which underlie such old 
alluvia belong, without exception, to the earlier stages of the Glacial 
