MAKIXG THE ROCK BOTTOM. I J 



granite, because the cleavage is very poor ; it tears apart 

 irregularly when blasted instead of splitting in smooth 

 lines.* The poor splitting quality may be accounted for 

 partly because this granite was disturbed too much while 

 cooling. In some places it appears to have been pushed 

 and twisted and kneaded while it was in process of 

 crystallizing. In some of these snarled masses while the 

 crystals were being formed they were drawn into shapes 

 like the coils of candy. A pretty specimen of this flow 

 structure is to be seen in a loose bowlder on South Main 

 Street, about three hundred yards before reaching the 

 Scituate line. Other cases are to be seen in the freshly 

 blasted ledges along both sides of Jerusalem Road where 

 it skirts the north shore of the town. 



While these crystals were forming into phalanxes, there 

 was a choosing of sides that continued apacCo The quartz 

 kept moving towards the lower and hotter portions of the 

 pasty mass, while the hornblende and feldspar gathered 

 most thickly towards the outside or upper part. The result 

 is that there are three grades of granite to be seen now 

 in Cohasset. The most plentiful is that middle kind 

 which is a fairly even mixture of quartz and feldspar with 

 a little hornblende. 



It is light gray or pinkish in color, with larger crystals 

 generally than those of the darker granite which formed 

 above it. In the outer or darker granite there is much 

 more of hornblende and mica, with much less of the 

 quartz. The crystals of hornblende and of feldspar can- 

 not show so prettily because of the lack of quartz. 



The third or inner sort of granite is not very visible 

 because only a little has ever come up to daylight. That 

 little has come up through the cracks in the other and 



*John C. Howe, ten or more years ago, opened a quarry on the southwest 

 side of Town Hill, to get some stone for foundations and walls ; but the work was 

 very difficult. Another was worked for a short time, fifty years ago, on the shore 

 north of Sandy Cove. Still another has been pointed out to me in the woods a 

 quarter mile west of Atlantic Avenue, back of Nathaniel Treat's home. 



