78 
A RECORD OF TIME 
rock bears testimony that he was here and lived his 
life and fought the ceaseless fight for existence ♦ 
Then the record tells of cold too intense for animal 
or vegetable life* For ages a continent of ice, seem- 
ingly immovable but for ever moving, ground the 
rugged fragments of rock into symmetrical boulders* 
These are imbedded in hard clay, the accumulation 
of a long era of glacial action* That the continent of 
ice moved is shown by the worn and pulverised rocks 
as well as by the continuous motion of the glacial ice 
still remaining elsewhere* That it yielded to a warmer 
era is shown by the abundance of animal and vege- 
table remains in the supervening gravel and sand* 
Here the shells are still preserved, and the remains 
of some fifty species have been collected* Many are 
remarkably perfect* 
The great majority of these species are now extinct, 
but some of the Clams still survive, an evidence 
of the limit of subsequent destruction* The climate 
was milder than any that has been experienced in 
this region during the present geological era* The 
Osage Orange and other trees now indigenous to the 
Mississippi and Ohio valleys are found in abundance* 
A good-sized tree-trunk taken out was cut up and 
used by a cabinetmaker, the few hundred thousand 
years it had lain there under water, ice, and dry 
earth, having served to improve rather than injure 
it* The discovery of a Fish's head was a new revela- 
