The Geology of Hingham. 43 



of fossils in any of them makes it impossible to determine defi- 

 nitely their age. The fact of slates within half a dozen miles of 

 the town containing trilobites, thus showing them to be primor- 

 dial, has led reasonably to the view that a part at least of those 

 in Hingham might be found to be also primordial. The super- 

 position of the strata, however, and their inclination, as far as 

 these can be studied at their exposures, militate against this 

 view. Nevertheless, considering how much is hidden from obser- 

 vation where the great body of slate lies, towards Weymouth 

 River, and the disturbances to which the formations have been 

 subjected, it is by no means to be regarded as settled that slate 

 of primordial age does not exist in Hingham as in other parts 

 of the basin. It cannot, however, be shown that any is found 

 resting; beneath the rocks of the Conglomerate Series. That 

 which occurs alternating with the conglomerate must be regarded 

 as of the same age as the conglomerate itself. The great body 

 of slate referred to above, towards Weymouth River, seems by 

 its dip, as far as this has been determined, to be superior to the 

 strata of the conglomerate series, and therefore a later rock. 



This slate, on the maps is designated separately from that of 

 the conglomerate series, as belonging to the Slate Series. 



The Conglomerate Series comprises Conglomerates, Sandstones, 

 Slates, and Melaphyr, which have together a thickness of nearly 

 one thousand feet. The great disturbances alluded to, by which 

 all these rocks were rent asunder by faults, and forced into ap- 

 proximately vertical positions, will be more clearly apparent by 

 a glance at the maps than by hours of reading. 



THE CONGLOMERATE SERIES. 



Conglomerate is formed of pebbles or angular fragments and 

 gravel derived from pre-existing formations, these being cemented 

 together into a compact rock. Sometimes the enclosed masses 

 are of considerable dimensions, being several feet in diameter. 

 When the enclosed stones are pebbles, that is, are rounded, the 

 rock is called Pudding-Stone ; when they are angular it is called 

 Breccia. The pebbles or fragments vary much in character, — 

 those of Petrosilex, Quartzite, Granite, and other rocks being often 

 found in close juxtaposition. Such is the case with the conglom- 

 erate of Hingham, as may be seen at almost any exposure. When 

 the rock is "found made up exclusively of fine material, small 

 gravel, and sand, it becomes a sandstone, and as such occurs in 

 Hingham alternating with the coarser portions. 



Conglomerate is the predominant rock over considerable areas 

 of the town. It presents itself prominently in the harbor, com- 

 posing the strata of the islands known as Sarah's, Langlee's, and 

 Ragged, and its walls face the water along the coast front of 

 Melville Gardens. It crops out upon the surface in great abun- 



