146 COAL AND COAL-FORMATIONS. 



It is true that in the older formations we have but a very 

 scanty exhibition of coaly substances, and it is equally true 

 that hitherto the most extensive developments have been 

 found in strata of Carboniferous age ; but it is nevertheless 

 the fact that coal-fields of great value occur in the oolitic 

 and cretaceous rocks, and that brown-coals are common in 

 almost every tertiary district. It may render the subject 

 more intelligible and attractive if we take the formations 

 seriatim beginning with the recent and apparent, and 

 working down through the older and more obscure. 



The coals of the present day are the peat-mosses, the 

 swamp-growths, and the vegetable drifts borne down by 

 rivers and deposited in their estuaries. We have no means 

 of ascertaining the extent or thickness of vegetable drifts, 

 though some, like the " Rafts" of the Mississippi, are of con- 

 siderable thickness and extent; but we know that large areas 

 in all the temperate and colder latitudes are occupied by 

 peat-mosses and swamp-growths the lake region of North 

 America, Canada, the Southern States, Siberia, Northern 

 Europe, Denmark, Holland, and our own islands.* These 

 are often of great thickness, and date from the growth of 

 the current year to the very dawn of the Quaternary epoch ; 

 loose and turfy above, firm and peaty a few feet down, 

 and at greater depths black and dense as some varieties of 

 lignite. Indeed, we have seen varieties of Dutch peat taken 

 at 30 feet deep indistinguishable from some lignites ; and 



* We have no reliable statistics of the extent and thickness of peat- 

 mosses either in Europe, Northern Asia, or North America ; but in the 

 recently published Eeport on the Geology of Canada by Sir William 

 Logan, a number of details are given, from which we learn that upwards 

 of 300 square miles of that country are occupied by peat-mosses varying 

 from 3 to 30 feet in thickness. If such be an approximation to the 

 amount of peaty surface in the surveyed portion of Canada, the amount 

 in the whole of British North America, Northern Europe, and Northern 

 Asia, must be something enormous. 



