198 



THE CARBONIFEROUS SYSTEM. 



previously mentioned, was a pillar of coaly matter, without distinct 

 external markings, and compressed by latei'al pressure. Its preserva- 

 tion in this manner shows that it was composed of durable wood, but 



Fig. 40. — Beds overlying Joggins Main Coal, loith erect Tree and Calamites. 



1. Shale and sandstone. Plants with Spirorbis attached; Rain-marks (?) 



2. Sandstone and shale, 8 feet. Erect Calamites. r . ^ .. ,„, ^ 



„ ^ , . „ .\ An erect coniferous (?) tree, rooted 



3. Gray sandstone, 7 feet. ^, , , i, , . , 

 ^ _ , , , . ' ■< on the shale, passes up through 15 



4. Gray shale, 4 feet. 1 r . i-., j. -, , , 



^ „ , ' , , ^ I feet of the sandstones and shale. 



5. Gray sandstone, 4 feet. i- 



6. Gray shale, 6 inches. Prostrate and erect trees, with rootlets; leaves; Naiadites ; and 



Spirorbis on the plants. 



7. Main coal-seam, 5 feet coal in two seams. 



8. Underclay, with rootlets. 



by no means proves that it differed from those trees which are found 

 in the state of stony casts. An erect tree, the wood of which had 

 time to decay before it was buried by detritus, would appear as a cast 

 in sand or clay. The same tree, if broken off and buried before the 

 decay of its wood, might appear as a pillar of coal. This tree is, 

 however, proved, by portions of its wood which retain their structure, 

 to have been coniferous. 



After deposits of sand had extended to the height of at least ten 

 feet above the root of this tree, and while its top projected above the 

 surface, Calamites grew around, attaining a diameter of If inch, and a 

 height of at least five feet. They are very numerou.s, and though 

 perhaps a different species from those in the great calamite bed before 

 mentioned, grew in the same manner. They were buried by five feet 

 of sand and arenaceous mud, after which their tops and that of the 



