HOW OUR COAL WAS MADE 227 



brown, powder-like spores, and the fronds of the 

 ferns, large and small, dropped down, too, into the 

 water. The trees grew old and died, and, falling, 

 filled the swamp with their great decaying trunks 

 and branches, until what had once been long sheets 

 of water became thick, oozy marshlands Uke a 

 bottomless bog. 



Often during those ages in which the forests were 

 growing and filling in the pools with the thick, 

 black mold, the sea would try to reclaim a part of 

 the marshy land, and make it into a strip of beach 

 once more. The waves would come rolling in, bring- 

 ing clay and sand which would spread over the sur- 

 face of the marsh and cover up the masses of branches 

 and stems and fern fronds that lay there. If the sea 

 held its sway long enough, the mighty trees would 

 finally die and, falling, be covered by the burden of 

 sand each rolling w^ave brought in, until all evidences 

 of a forest would be gone, — buried far beneath the 

 waves of the victorious sea. 



In time, however, the sea would build a barrier 

 even against itself, so that the waves could no longer 

 roll in over the higher beach, and cover the swamps 

 with sand and clay. Then the rain and river water 

 again collected behind the high beaches, again 

 made swamps in which trees and ferns commenced 

 to grow. So in time there was another immense 

 forest growing upon the clay and sand that had 

 covered up the older one. In some places the ocean 

 overthrew and buried many forests, one after an- 

 other, before it was finally conquered and the land 

 along the seashore rose and became dry ground. 



