MAKING THE ROCK BOTTOM. 2<) 



scratches that one piece has given to the other. In the 

 center of the village on the east side of Main Street, within 

 a hundred feet of the engine house, there are several of 

 these scratched places on the ledge of rock within reach 

 of every passer-b3^ The vertical marks show how the rock 

 on the west side of that ledge — possibly acres of it under- 

 lying the road and the railway station, that whole neigh- 

 borhood — was dropped downward. At the same time 

 the rocky ledge upon which the Grand Army Hall is 

 perched was borne upward by the heaving crust of earth. 



There may be, indeed there must be, many other places 

 in the cracks of our ledges where the scratches of faulted 

 rock might be exposed if only a piece were to be blasted 

 out to show it as in this case. 



Sometimes in cruising through the woods of our town 

 men come to the abrupt wall that terminates a ledge ; and 

 their guess is not very far from facts when they imagine 

 that where the low bog now lies was formerly the solid 

 rock that slipped downwards to accommodate the displace- 

 ments of the earth's crust beneath. 



On the north side of the town next to Straits Pond, 

 Jerusalem Road runs along the side of a granite wall that 

 has lost all that used to belong to it upon the north, by 

 a deep faulting. 



Just across the road from the granite ledge the rock is- 

 wholly conglomerate. Far down beneath the conglomer- 

 ate rock Professor Crosby assures us that there is to be 

 found the granite which used to be continuous with our 

 northern wall of granite before Boston basin slumped 

 downwards into the interior. 



The conglomerate, and all the lava that was poured out 

 into this basin, is sadly jumbled and is faulted very much 

 more than our Cohasset rock bottom. 



But the comparatively small amount of our faulting 

 is enough to contribute a large degree of the beauty and 

 the variety of our ledges and lawns. Our harbors, both 



