THE ORIGIN OF COAL 



smallest leaf; the weight of the superimposed mud 

 crushed the softened tree-trunks; a gradual decay 

 converted the whole into charcoal; and finally the 

 ligneous mass became a layer of coal. Later the 

 waters changed their bed, driven elsewhere by up- 

 heavals in the surface of the earth, and the pre- 

 viously inundated bottom-lands became solid ground 

 in which to-day we find coal under massive strata 

 of rock. 



"Is it possible to distinguish the forms of plant- 

 life whence has come our coal? Yes, it is possible, 

 so well preserved are the details of that life in the 

 products of our mines. Now an examination of the 

 imprints left to us in the lamina or leaves of our 

 stone book shows us that the plant-life of those re- 

 mote ages in which the coal was accumulated bore 

 not the least resemblance to that of our present for- 

 ests. And this difference was to be expected. The 

 animal life has changed ; why, then, should the plant- 

 life have remained unaltered?" 



"Didn't they have trees then like ours?" asked 

 Jules. 



"No," replied his uncle; "we do not find in our 

 coal mines any signs of the existence of trees re- 

 sembling those of our day. Nowhere in the world, 

 in fact, are there now to be seen any such forms of 

 plant-life as flourished so abundantly in those remote 

 ages; or if any still exist that are at all analogous, 

 they must be sought in the islands of the tropical 

 seas. No vegetable growth of that coal epoch, 

 whether tree or bush or simple cluster of leaves, 



