TRY 



Pocket-gopher 585 



But as already seen, these animals are more or less active tire- 

 the year round, and even halving the lowest estimate of their indus- 

 numbers to cover sparsely populated regions, and again halving 

 the estimate of their work to allow for periods of comparative 

 idleness, we shall still have an even upheaval of between two 

 and three inches per annum. 



In Colorado I made a number of observations that seem 

 to more than justify this conclusion. For example: 



September 22, 1901. Camp on Wilson's Flat-top, Colo- 

 rado. Here, as elsewhere noted, the whole country is up- 

 heaved by Pocket-gophers. Aspen logs with the bark on, rot 

 in three years," if set in the ground, and in five above ground; 

 and yet I found here many fallen trunks eight inches in diameter 

 that were completely sunk, buried out of sight, by the labours 

 of these miners before the wood was at all rotted. This would 

 mean an upheaval in that place of at least eight inches in less 

 than five years. 



Darwin concluded that the earthworms in five years bring results 

 up soil enough to cover the ground one inch thick, and that, 

 therefore, the result of its labour is of vast importance. I 

 reckon that the Pocket-gopher does this much in five months. 

 It does not do it in the same way or so effectively, because the 

 earthworm actually digests the substance of its castings, but 

 it is evident that the Gopher's method answers the purpose 

 of fully disintegrating and mixing the dead vegetation with the 

 soil to produce a rich and fertile black loam. 



From these observations we may form some idea of the 

 work done toward tilling and draining the ground by this 

 continental army of rodents, and it is possible that they cause 

 still greater changes by bringing such vast quantities of soil 

 under the influence of the sun and wind. 



Their aggregate power as active geological agents must be 

 immense, and when we stand on the banks of the Mississippi 



" " Pieces of wood, 2% inches square, were buried to the depth of i inch in the 

 ground, and decayed in the following order: Lime, American birch, alder, and aspen 

 in 3 years, etc. etc." J. H. Balfour, Manual of Botany, 1855, London and Glasgow, 

 P- 45- 



