182 



THE CARBON IFEKOUS SYSTEM. 



beds were being gradually accumulated by the growth and death of 

 animals. In the highest of these beds of mud, which probably restored 



Fig. 31. — Fossils from Bitiuuinous Limestone — Joggins. 



Cypris, 

 {a) natural size. 



Spirorbis, 

 (a) natural size 



Naiadites.' 



Ganoid Scales. 



the whole area to the state of a swamp, trees took root and were 

 buried by an irruption of sand, in which they, as well as an under- 

 growth of Calamites, still stand in an erect position. 



I have dwelt at some length on this subdivision, not that there is 

 anything very remarkable in its structure, but that its appearances 

 will help to explain others that succeed. It is evident that when read 

 in the light of modern geology, they tell a very intelligible tale, and 

 show us that the circumstances in which these coal-rocks were formed 

 were similar to those which we have found to exist on a small scale in 

 the modern marshes of the Bay of Fundy ; and also to those more 

 extensive changes which occur in the deltas of great rivers, such as 

 the Mississippi and the Ganges, in which low alluvial flats have often 

 been alternately covered with water and with a dense swamp-vege- 

 tation. Let the reader also observe, that in this group of the Joggins 

 beds, we have at least five successive soil-surfaces, four of them suffi- 

 ciently permanent to permit the accumulation on them of peaty vegetable 

 soils ; and about four feet nine inches of calcareous beds, mostly made 

 up of animal remains. The lapse of time required for the accumulation 

 of this group alone must thus have been vastly greater than that 

 necessary for the production of the modern marsh formation with its 

 one fossil soil. It will also be observed that these beds carry our 

 thoughts back to a period when the district was covered by a strange 

 and now extinct vegetation, and when its physical condition resembled 

 that of the Great Dismal Swamp, the Everglades of Florida, or the 

 Delta of the Mississippi. 



One appearance only in this subdivision requires farther explanation 

 before we proceed to the next. One of the sandstones in the upper 

 part exhibits trees standing out from the cliff, as pillars of hard sand- 

 * For other figures and desriptions of these fossils, see notice at the end of this chapter. 



