THE GRAY GOPHERS 123 



Canada, there are no earthworms to act as pre- 

 historic cultivators. The black loam there is 

 from one to two feet thick, and is a thoroughly 

 mixed soil of both mineral and vegetable par- 

 ticles. There is no doubt that, in the absence 

 of earth worms, this mixing is done by burrow- 

 ing animals, by far the most important of which 

 is our subject. In his great work, Life His- 

 tories of the Northern Animals, Seton shows by 

 text and drawings what an astonishing number 

 of active gophers there are (or were) over 

 every square mile of that and other regions; 

 and the still more astonishing bulk of soil 

 brought to the surface from deep layers day 

 by day. He cites a district in California with 

 an estimated average of 6,000 hills to the acre, 

 and enough soil heaved out each summer to 

 cover the whole with an inch of new earth ; and 

 other similar cases elsewhere. "If the fertility 

 of tens of millions of acres of land in the North- 

 west, and consequently their value, has been 

 mainly the work of moles [pocket-gophers]," 

 declares Dr. Robert Bell, the Canadian geol- 

 ogist, after giving proof for his thesis, " these 



