TREES THAT KEEP A DIARY 91 



should realise that the trees contain the most au- 

 thentic records in existence. 



It is to fossil tree diaries contained in geologic 

 and coal strata of the earth that we turn for prac- 

 tically all our information about the carboniferous 

 and coal measure world periods. Tree trunks, 

 often having roots and branches attached, tell us 

 intimately of the long distant ages in which they 

 flourished. Cones and leaves indicate their forma- 

 tion in great detail. The coal-forming ages were 

 those of great ferns and conifers. The calamites 

 were sort of immense asparaguses and related to 

 our modern ferns known as horse-tails (equisetum) . 

 They grew by underground stems which sent up 

 shoots into the upper world at intervals. The hum- 

 ble three-foot lycopodes of our day, whose chief 

 means of protection against grazing animals are 

 their ability to poison their destroyers, were 80- 

 foot trees then. The segillarias rose to a height 

 of 100 feet. Queer spotted and corrugated trunks 

 lifted their thick heads everywhere out of the 

 marshy and fog-covered land. Flowers were hardly 

 in existence. It is estimated that it required the 

 passage of 122,500 years to accumulate sixty feet 

 of coal. We are indeed fortunate in having numer- 

 ous tree diaries to help us mentally reconstruct 

 the mighty age in which they lived. 



