Considering, then, the length of time required to lay
down a thousand feet of strata, and considering the vast difference
between the animals found in them, and the few found in the New Red
sandstone, we have a right to call them another world, and that one
which must have lasted for ages.
After we pass Oxford, or the Vale of Aylesbury, we enter yet another
world. We come to a bed of sand, under which the freestones and
their adjoining clays dip to the south-east. This is called commonly
the lower Greensand, though it is not green, but rich iron-red. Then
succeeds a band of stiff blue clay, called the Gault, and then
another bed of sand, the upper Greensand, which is more worthy of the
name, for it does carry, in most places, a band of green or
"glauconite" sand. But it and the upper layers of the lower
Greensand also, are worth our attention; for we are all probably
eating them from time to time in the form of bran.
It had been long remarked that certain parts of these beds carried
admirable wheatland; it had been remarked, too, that the finest hop-
lands--those of Farnham, for instance, and Tunbridge--lay upon them:
but that the fertile band was very narrow; that, as in the Surrey
Moors, vast sheets of the lower Greensand were not worth cultivation.
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