THE POLAR ZONE. 17 



the climate of the Polar regions must at some time have 

 been warmer than it is at present. The beds of coal, for in- 

 stance, which were discovered during Captain Parr/s re- 

 searches, both in Melville Island and in Jameson's Land, in 

 Old Greenland, bear silent witness to the previous exist- 

 ence of forests there ; coal-beds being now pronounced by 

 geologists to be the remains of ancient forest timber in a 

 mineralized state. 



