201 



lying slute, the latter undoubtedly marking the position of a 

 synclinal axis ; but the south side of the syncline is probably 

 cut off by the boundary fault, for we seem to [)ass abrui)tly 

 from the slate to the granite. In the vicinity of Hockley 

 Lane a transverse fault appears to separate this normal suc- 

 cession of the strata from an inverted succession which extends 

 thence eastward to Main Street or beyond. The melai)hyr is 

 now on the south side, overlying the conglomerate ; and these 

 stratified rocks, althougii occui)ying a synclinal position 

 between the granite on the north and soutii, are, we must 

 suppose, bounded on both sides by important liislocations and 

 terminated on the east by the great fault along the east side 

 of Hingham Harbor. 



Noi'thwest from the western extremity of the granite axis, a 

 very steep, narrow, and broken monocline separates the granite 

 from the great trough holding the main body of slate. This 

 faulted monocline is marked by a second band of mela[)hyr, 

 which broadens toward the northeast, forming the larg(! quad- 

 rangular area of this rock east of Huit's Cove. This is the 

 largest exposure of mela[)hyr in Hingham, and, although it 

 appcivrs to be bounded on all sides by downthrow faults, the 

 quaquaversal dips of the bordering strata show that, in a lesser 

 degree, it is essentially similar in its structural relations to the 

 granitic area. On the west side, the upper bed of conglom- 

 erate and the slate are seen to di[) away from the melaphyr. 

 On the north, the downthrow of the sedimentary rocks is suffi- 

 cient to conceal the conglomerate, and the slate lies with 

 conformable strike against the melaphyr. On the south, the 

 narrow monocline se[)arating this body of melaphyr from the 

 granite broadens somewhat, until it reaches the fault at the 

 northwest end of Squirrel Hill, where it changes, perhaps 

 abruptly, to a broad shallow syncline of melaphyr and con- 

 glomerate on the south, separated by a strike faidt from a 

 gentle southerly monocline of conglomerate and sandstone on 

 the north. These features probably extend east under Broad 



