254 Physical History of the Trias. 



where it forms a peculiar brecciafced marble, used for the columns in the 

 Capitol at Washington. 



Note C. — There remains still another parallel between the deposits now 

 forming in the Bay of Fundy and those laid down in the old Triassic estu- 

 ary. A.t the northern end of the Bay of Fundy are the Tantra marshes, 

 covering thousands of acres, and evidently produced by the filling up of 

 that portion of the bay. The material forming these prairie-like marshes is 

 in many places a carboniferous mud, fitted under the necessary condi- 

 tions to form a carbonaceous shale or slate, in which vegetable impressions 

 and the remains of animals now living would not be wanting. Such a 

 swamp deposit, formed on the border of a great estuary subject to extremely 

 high tides, would suffer many interruptions, and be less regular than the 

 coal deposits of the great carboniferous marshes. We may reasonably infer 

 that the geologist of future ages will find in the region now occupied by the 

 Bay of Fundy a great formation of sandstone and shale fringed on either 

 side by shore deposits, as already said, and at the northward passing into 

 an irregular accumulation of carbonaceous shales, slates, and sandstones, 

 in many places rich in fossils, and perhaps also carrying coal. 



Turning now to the Trias, we recognize, as already shown, the deposits 

 of the open estuary in Connecticut, New Jersey, etc., but far to the south, in 

 Virginia and North Carolina, we find the swamp deposits of the same estuary 

 in the coal fields near Richmond and those on the Deep and Dan Rivers. 

 Here are conglomerate, carbonaceous sandstone, and shales, together with 

 beds of coal which are sometimes of great, though irregular thickness. These 

 deposits appear in rapidly changing successions, and were evidently formed 

 in the swamps on the border of the Triassic estuary, where the shores were 

 low and favorable to such conditions. These accumulations of carbonaceous 

 material along the swampy shores, we consider synchronous with the beds 

 of sand and mud found in the open waters of the same old a estuary. This 

 seems to us a very simple and natural explanation of the occurrence of coal 

 only in the extreme southern end of the region of Triassic rocks, and of its 

 absence in the northern areas. It is the reversal, as regards their relative 

 position, of the swampy shore and open bay conditions now to be observed 

 in the Bay of Fundy 



The coal-bearing areas at the south, like the conglomerates fringing the 

 borders of the Trias to the northward, must alike be classed as shore depos- 

 its. They enable us to trace still farther the outline of the ancient estuary 

 in which these now detached remnants of Trias were deposited. 



