VALLEYS. 
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miles across country, and were long supposed to be 
ancient coast lines, are now ascertained, mainly 
by the researches of Whitaker, to be due to the 
differential action of subaerial causes. The Chalk 
escarpments in our own country and the great wall 
of the Bernese Oberland are of this character. 
That the longitudinal valleys owe their origin to 
the same cause as the mountain chains, may safely 
be inferred from the fact that they follow the same 
direction. They are in fact negative mountain chains. 
Transverse valleys cross the strata more or less 
at right angles. They are generally narrow, and 
often form deep gorges, more or less encumbered by 
fallen rock, and the harder the rock the narrower the 
valley. 
Their character is greatly influenced by the 
