THE CARBONIFEROUS SYSTEM. 125 
The peculiarities of the cannel coals, which have been already referred 
to, have also been ascribed to the vegetation from which they were de- 
rived; but I think it can be plainly shown that they owe their charac- 
teristic features to the method in which they have been formed. As the 
result of many years’ study of our coal strata, I suggested, in a paper 
published in the American Journal of Science in 1857, that cannel coals 
were formed in lagoons of open water in the coal marshes, and that in 
these lagoons the completely macerated vegetable tissue—probably for 
the most part parenchyma—accumulated as a fine carbonaceous mud, 
and all mv subsequent observation has tended to confirm this conclu- 
sion. The evidence upon which it rests is briefly as follows: 
ist. The cannel coals in their intimate structure are more homoge- 
neous than the cubical coals, and show nothing of the alternations of 
bright and dull lines to which reference has been made, and which we 
may consider as proofs of changing surface conditions in the coal marsh. 
2d. Though not laminated in the sense that the cubical coals are, the 
cannels are more distinctly stratified like other rocks which are deposited 
from aqueous suspension. 
od. The cannel coals generally contain a greater percentage of vola- 
tile matter than the cubical coals, and the gas made from them consists 
more largely of hydrogen, and has higher illuminating power. All of 
which is a natural result of their deposition in a hydrogenous medium 
which prevented oxidation. 
4th. Cannel coals, as a class, contain more ash than the cubical coals, 
and they frequently pass into bituminous shale. This occurs where the 
_ water from which they were deposited had a more rapid motion and 
- greater transporting power. It then carried and mingled with its car- 
bonaceous sediment an increasing and ultimately preponderating amount 
of mineral matter. 
6th. Cannel coal contains, as characteristic fossils, aquatic animals, 
such as mollusks, fishes, amphibians, and crustaceans. These are some- 
times so abundant and of such a character as to prove conclusively that 
they inhabited pools of water in which cannel coal was deposited as a 
sediment. Where plant remains are found in cannel, they are usually 
floated fragments which show the effect of long maceration—fern fronds, 
for example, being usually skeletonized. 
6th. In the lagoons of open water found in our modern peat marshes 
fine carbonaceous mud accumulates, which, when dried, closely resem- 
bles in appearance and properties our cannel coal. 
With such evidence before us, it seems that there should.be no great — 
difference of opinion as to the origin and mode of formation of cannel 
coal. 
