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-si^ed 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- 



