1575.] 403 [Dodge. 



Slates also appear in this line of strike, on the road to Hough's 

 Neck and on Slate Island, one and a half and five miles to the east- 

 ward. At Rock Island Cove on Hough's Neck, there is conglomerate 

 varying to sandstone with large quantities of light gray and greenish 

 eruptive rock. 



( f.) In the South Shore district, the slates are so involved with the 

 crystallines on the one hand as to afford many opportunities of study- 

 ing their strati graphical relations. 



In Hingham, the slates which lie between the conglomerates and 

 the crystallines on the south of this district, are probably part of the 

 conglomerate system. The others, farther north, seem to belong to 

 an older, or, at least, different series. 



Between the second and third crystalline bands, there are slates 

 along the Old Colony Railroad, appearing at the surface nearly the 

 whole distance from the bay of Weymouth Fore River, west of North 

 Weymouth Station, to, and a little beyond, Weymouth Landing. They 

 lie parallel to the northern limit of the second band, and are nearly 

 vertical. On White's Neck, near the bay and a few rods north of the 

 railroad, they are of the common argillaceous variety, but along the 

 track, they are thin and soft, smooth and slippery. They are cut by 

 quartz veins, and near these they sometimes assume an appearance 

 like black plates of mica. The surfaces are often bronzed. Toward 

 Weymouth Landing, igneous outflows are so abundant that it is diffi- 

 cult to determine whether the rock is the intrusive with slate frag- 

 ments, or slate cut by the intrusions. Just east of the station, the 

 slates are hard and black, and have nodules of pyrites. From here 

 westward, they are very closely locked in among the crystallines, 

 alternating at the surface with these, or in spots among them. On 

 the north side of Monatoquot River the crystallines occur on each 

 side of Quincy Avenue, and westward, very near the railroad at East 

 Braintree station. On the south side, they appear along Union Street 

 and between it and the river. Just west of Quincy Avenue these 

 give place to slates cut by igneous intrusions which extend to the cor- 

 ner, and crop out also on the east side of Quincy Avenue opposite 

 Union Street. In these places, the slate often resembles that of the 

 Braintree trilobite quarry. 



(g.) Passing north from the crystallines of the second band at 

 this place, we come at once upon those of the third, which occupy the 

 region between Monatoquot River and Quincy. The Paradoxides 



