183 



opinion, but have observed many facts pointing to the contrary 

 conclusion ; Adz., that the areas covered by the uncrystallines of 

 Eastern Massachusetts have never much exceeded their present 

 limits. These sediments, consisting of conglomerates, sand- 

 stones, and slates, have evidently been deposited in shallow 

 water, and in close proximity to the land ; the arenaceous 

 beds particularly being often ripple-marked, and also showing 

 wave action in their irregular stratification. Mr. Matthew 

 appears to hold a similar view with respect to the Cambrian 

 beds of New Brunswick, the evidence being plain that they 

 were formed at a time when the sea and land had something 

 near their present relations. The indisputable want of synchro- 

 nism between the deposits of the Boston and Narragansett basins 

 is inconsistent with the theory of their original continuity. 



I have noted the occurrence of rocks of the Shawmut group 

 in each of these ancient bays, and in a preceding paragraph it 

 is implied that the Narragansett basin is filled mainly with Car- 

 boniferous strata. The River Parker and Boston basins, on 

 the contrary, contain, so far as known, in addition to the 

 Shawmut breccia and amygdaloid, only rocks of Cambrian 

 age. These last are believed to all represent about the same 

 horizon as the Paradoxides bed in Braintree, belonging, with 

 that, to the Acadian epoch of the Primordial period. 



PKIMOEDIAL. 



Boston Basin. 



The most diligent search, continued for many years, by, in 

 the aggregate, a small army of observers, has failed to bring 

 to light, among the rocks of the Boston basin, more than one 

 locality affording fossils. This is the celebrated slate quarry 

 on the south shore of Hay ward's Creek, in the extreme north- 

 east corner of Braintree. These slates, containing Paradoxides 

 Harlani, are on the southern edge of the basin, and closely 

 involved with the granite ; but this highly characteristic fossil 

 serves to connect the strata holding it with the Primordial rocks 



