348 G. K. GILBERT 
or greater transportation on lower slopes, tending to produce a con- 
cave profile, is not easy to see. 
As wind and rain beat are effective only on bare surfaces and 
surfaces imperfectly clothed by vegetation, while convex hilltops 
are found alike in forested regions, prairies and deserts, it is evident 
that their work is not of prime importance in this connection. Soil 
creep is omnipresent and appears to be competent. 
Fic. 4.—Miniature hills, illustrating the convexity of divides. 
The development of gullies on convex slopes when vegetal pro- 
tection is removed, does not import a transformation to concave 
slopes and acute water partings, but merely a change in what Fen- 
neman aptly calls the texture of the topography—a reduction of 
the scale of the drainage pattern and hill pattern. The removal of 
vegetation gives water flow greater velocity, thereby enlarging the 
domain of stream sculpture, with associated concave profiles, and 
reducing the domain of creep and convexity. 
Figs. 2, 3, and 4 show mature hill forms developed in homogeneous 
material. They occur on the floors of hydraulic gold mines at 
