13 
themselves * When the Men of the Polished Stone Age appeared’ 
they were accompanied by the domestic horse and dog, and agricul- 
ture was well developed among them. They were also contem- 
porary with a fresh set of wild animals; the Mammoth and the 
Woolly Rhinoceros are gone; tho Cave Lion and Cave Bear have 
disappeared, ‘‘ the two sets of men, their remains, and their animal 
companions are sharply and definitely separated by a complete 
gap. ‘‘ The deposits of the Mammoth age, and it would seem of the 
Reindeer Age as well, are covered with beds of yellow earth, brick 
earth, and earth with angular stones, which antedate the later 
stone age. These deposits are of the same nature with the super- 
ficial gravel, soils, and loess to be found resting on the Pleistocene 
deposits everywhere in the northern hemisphere, and which have- 
poured into all the old caverns of the Palwocosmic Age.” No- 
Mammoth remains occur above such deposits. 
What happened between the two great Stone Ages to cause this 
*oap?” Had it anything to do with the disappearance of the 
Mammoth? . 
I am now crossing the borders and entering the Debateable Land,. 
where little is certain, and where every point brought forward will 
‘give ample opportunities for discussion, of which I hope many will 
avail themselves. : 
You must know that among students of geology there are two 
schools of thougut, including what are termed Uniformitarians and 
Catastrophists. The former, with Sir C. Lyell at their head, believe. 
that physical changes have always been going on in the world in 
much the same way as they are going on now; the same agents at: 
work—rivers, rain, frost, and fire; and varying little if at all from 
their present normal rate. Itis they who make such enormous 
demands for past time, as they must necessarily do in order to- 
account for such results at a slow rate. The Catastrophists on the 
other hand refuse to be bound down in this way; they do not deny 
the similarity or even the identity of the agencies of change, but. 
they hold that these agencies have in old times acted occasionally 
with far greater violence and intensity than they ever do at 
present. And there is a great deal to be said in favour of their - 
views. 
Like all enthusiastic partizans, adherents of both sides are apt to. 
make very positive and sweeping assertions occasionally, against 
- which it is necessary that we should be on our guard. You may 
know them by their use of such phrases as—‘ It can easily be 
shown, &c.”’ ‘It is a well-established fact, &c.”’ ‘‘ This theory is 
now exploded, &c., &c. Several ‘exploded’ theories have lately 
* The Statement refers only to the Men of the River Drifts, not to the Cave-men 
who may possibly be represented now by the Eskimos. 
