1 2 HIS TOR Y OF COHASSE T. 



Subterranean pressure and subterranean heat make a 

 complicated condition of affairs that cannot be reproduced 

 in our artificial devices, though it may be fairly well under- 

 stood. The facts about granite such as these noted, and 

 many others wherever granite is found, tell very conclu- 

 sively that it was not formed as limestone and sandstone 

 and slate and other sedimentary rocks by a deposit on the 

 earth's surface, but rather at a prodigious depth under the 

 solid ground, and by the slow crystallizing of molten sub- 

 stance. From two to five miles thick of other rock must 

 have lain upon the stuff that crystallized into granite. 



In some places of the world where the layers of rock 

 have been turned up edgewise by the earth's upheavals, 

 the granite appears, and the layers that formerly rested 

 horizontally upon it have been measured from surface to 

 surface, and thus have been ascertained to be miles thick. 



In the middle part of Massachusetts there is a layer of 

 slatestone which is ten thousand feet thick, and it shows 

 every indication that it once was spreading flat over all the 

 eastern part of the State and far out into the bed of the 

 ocean. It has been tipped up by a slight wrinkling of the 

 earth's skin, and that part which was over Cohasset has 

 been worn off by the waves and by the gases of the air 

 and by the rain washings of countless ages. 



Sir William Thomson, whose opinion in matters of 

 the age of this earth is the most mature, estimates that 

 twenty-five millions of years have passed by since the 

 Cambrian period, — the time when our granite began to 

 be pushed upward by the little wrinkle that was necessary 

 in the skin of the earth. If this estimate be true, the 

 pushing was so slow that if successive generations of 

 people had lived on top of the wrinkle they would have 

 Ijeen willing to swear an affidavit that not one inch had it 

 moved. But nature speaks more correctly the facts than 

 any human testimony. 



If our most reliable citizen to-day were asked whether 



