VALLEYS. 
179 
their way back, and thus tapped the valley. This is 
no doubt true in some cases, but cannot be accepted, 
I think, as a general explanation. 
Prof. Bonney* called attention to this tendency 
in his second lecture on the “Growth and Sculpture 
of the Alps.” “On considering,” he says, “the 
general disposition of the rocks constituting the 
Alpine chain, we perceive that, in addition to the 
long curving folds which determine the general direc- 
tion of the component ranges, they give indications 
of a cross folding. The axis of these minor undula- 
tions run from about N.N.E. to S.S.W.” 
He suggests three possible explanations: — (1) 
“That the Alps are the consequence of a series of 
independent movements, not simultaneous, so that 
the chain results from the accretion laterally of an 
independent series of wave-like uplifts; (2) that the 
chain was defined in its general outline by a series 
of thrusts proceeding outward from the basin of the 
North Italian plain, and afterwards folded transversely 
by a new set of thrusts acting at right angles to a 
N.N.E. line; (3) that the transverse disturbances are 
the older, and that the floor on which the Secondary 
deposits were laid down had already been disposed 
* Alpine Journal , Nov. 1888. 
12 
