Dodge.] 404 [February 3, 



quarry lies on the south shore of Hay ward's Creek, where the slates 

 are closely involved with the crystallines and eruptives. This crystal- 

 line range appears again to the eastward in North Weymouth, north 

 of the cemetery, and there, too, are large quantities of slate, par- 

 ticularly on its north side, cut by eruptives and with strike varying 

 from N. W.-S. E. to E. N. E.-W. S. W. Just across Hayward's 

 Creek, north of the trilobite quarry, is a little slate; and quarter of 

 a mile north, it appears again, south of Ruggles' Creek. Passing to 

 the eastward, parallel to the northern limit of the crystallines of the 

 second band, we find at the same distance from it as these slates 

 (about a mile and a half), another outcrop on Eastward Neck in 

 Weymouth between Howe's and Great Hills; and in the extreme 

 north-western part of Hingham, and on the north side of Hewitt's 

 Cove, other occurrences of similar character; black, thin and con- 

 torted. Possibly, unless glaciation has been too deep, careful search 

 westward on this line might disclose other slate outcrops among the 

 crystallines where the ground is low south of Penn's (or Payne's) 

 and Pine Hills, and toward Punkapog. Also about Town River, 

 east of the railroad. Some have connected the two districts (e) 

 and (/) in East Quincy, but I have seen no indications of the 

 topographical correctness of this. 



The slates in all these districts resemble each other closely, and are 

 very likely parts of the same system. I have, however, distinctly 

 marked the outlines of each district so that if they can be distin- 

 guished hereafter, they can be separated without destroying such 

 results here reached, as still may remain true. 



The slates vary in character from a compact flinty variety to dis- 

 tinctly laminated, or banded with different colors or textures, and 

 not unfrequently the wave action can be traced in the varying thick- 

 ness of the strata. 



In all the localities they are much disturbed by intrusions of igne- 

 ous rock (which is sometimes poured out over them), are faulted, 

 hardened and distorted. It is to these intrusions that we owe their 

 existence now in many places. The harbor slate islands and Nahant 

 bear witness to the protection against the sea afforded by their hard- 

 ening and sustaining agency. The conglomerate, if it ever existed 

 between the outer islands, has been worn away where the channels 

 now run. 



It is probably to these slates that search for fossils in this vicinity 



