203 



Table of the Ilingham Strata. 



Granitic roclvs (diorite, Jinuiite, and felsite). 



1. Conglonierato (basal). Tiiiclvucss uncertain. 



2. Molapliyr 120-240 feet 



3. Fine conglonierate and sandstone, alternating . . . 120-200 " 



4. Gray slate 40- 60 " 



5. Conglomerate, sandstone, and slate, alternating . . . 100-170 " 



6. Gray and red slate 'JO-130 " 



7. Conglomerate ;>0- 50 " 



8. Red slate 20- 40 '^ 



i). Conglomerate 40- 50 " 



10. Red slate 20- 30 " 



11. Conglomerate 75-100 " 



12. Red slate 50- 75 " 



13. Sandstone and conglomerate, alternating 200-300 " 



905-1445 " 



14. Gray slate 500 -f- 



Dikes of diabase intersecting; the bedded rocks, owinj^ chiefly, 

 it is probable, to the less continuous outcrops, but partly, no 

 doubt, to the fewei' faults, are much less conspicuous in Iling- 

 ham than in Nantasket. They probably agree with the 

 Nantasket dikes in dating from the plication and faulting of the 

 strata. The most important distinction is that between the 

 great masses of coarsely crystalline diabase scores or hundreds 

 of feet in breadth and very irregular in outline, and the ordinary, 

 narrow, wall-like dikes of finely crystalline diabase. The 

 latter, at least, belong chiefly to the east-west systems of 

 Nantasket. No clear intersections have been observed ; and no 

 dikes which could certainly be referred to the youngest or 

 north-south system of Nantasket. 



LITIIOLOGY. 



The rocks of Hingham are, lithologically, so similar to those 

 of Nantasket that a very brief treatment of this to[)ic will 

 suttice, the main purpose of these studies being to decipher the 



