THE TIME OF THE MAMMOTHS. 149 
by the usual standards of duration, yet only a geological 
yesterday. Once such journeys as we propose making were 
very difficult, and attended with dangers to soul, if not to 
body, whieh might well make any but the stout hearted in- 
vestigator hesitate. But now that the wall, which once di- 
vided the preadamie time from the present, has been so 
frequently breached and trodden over by those bound on 
expeditions into an even more remote past than that to 
whieh we seek to penetrate, we may set out on our journey 
without fear of meeting with a reception, on our return, 
which might make us wish that we had stayed among the 
monsters of that ancient time. 
We will not strain the imagination of the reader by asking 
him to conjure up a pieture of land and sea unlike that given 
by our present continents and oceans. He need not flatten 
out mountain ehains, or dry up river systems, in order to 
represent to himself a true picture of the theatre which bore 
the actors of the scenes we are about to describe. Our good 
old continent was much the same then as now. All the 
changes which have taken place would fall within the limits 
of error of the maps of the past few decades. The unceas- 
ing agents of change operating through water, have done 
much work; but a little longer delta to the Mississippi, a 
somewhat greater projection of Florida to the southward, 
a lessened area of the great lakes of the north-west, are 
about all the more important changes which have been ac- 
complished sinee the time of which we speak. 
In order to come in contaet with living elephants and 
mastodons, we need not go so far into the history of our 
continent as to traverse the glacial period. Long after the 
time when this great ice envelope shrouded the northern half 
of this continent, the great pachyderms continued to form 
the most important feature in the life of our continent. .If 
we wish to go back to the time when these great animals 
first came into our fields and forests we must ascend much 
farther into the past, beyond two or more glacial periods, 
