TRANSPORTED SOILS 45 



(4) gravity. It will be remembered that each of these 

 agencies was mentioned as active in soil -formation 

 through the physical and chemical forces brought to 

 bear on rocks. The material is moved from its original 

 position and laid down under new conditions which 

 develop properties entirely different from those pos- 

 sessed by sedentary soils. 



Of the four groups, those soils transported by water 

 are easily the most extensive, and next to these in area 

 stand those moved by glacial action. Wind-moved 

 soils are of much importance in some sections, but 

 gravity-moved soils are of small extent. 



15. Gravity or colluvial soils. In mountainous or 

 hilly regions, soil material of all dimensions is moved 

 down the slope under the pull of gravity. In those 

 sections of the country where stone fences are common, 

 the accumulation of soil on the uphill side of the fence, 

 due to gravity movement, not infrequently reach the 

 top of the wall. Because of its associations with a hill 

 (Collis meaning hill), such material is termed colluvial. 

 The first footings of soil in the niches and at the base 

 of a rocky ledge are usually of this sort, and in mountain 

 regions the accumulation of such material is sometimes 

 large. 



16. Water. -It has been shown how water is able 

 to transport sand and even boulders several times 

 heavier than itself, if it be flowing with a sufficient 

 velocity. (See page 24.) This large transporting power 

 may be observed in any creek or rivulet, and in every 

 hilly region it is brought forcibly to the farmer's notice 

 in the gullies formed by heavy rains. The bed of every 



