142 ETON NATURE-STUDY 



land covered with swamps of deep mud or ooze, interrupted by 

 stretches of water full of the creeping rhizomes of living plants and 

 of decaying vegetation. The temperature was higher than it is in 

 the tropical forests of to-day, and the continual mists produced a 

 dim shady light such as that found nowadays in the places most 

 frequented by ferns. In such a warm steamy atmosphere both 

 growth and decay were exceedingly rapid. Through forest swamps 

 of this kind there meandered rivers which deposited in their basins 

 masses of vegetable pulp mixed with silt. These beds have been 

 transformed in course of time into cannel coal. In what is now the 

 Welsh basin, heat or pressure, or both, fused the coaly matter and 

 turned it into the hard, shiny, formless condition now called 

 anthracite, which is the best steam coal for naval purposes." 



