868 Marvels of the Universe 
Photo by) (EL. A. Martin, F.GS. 
The raised beach at Brighton now stands twenty feet 
above the present beach. It rests on chalk, and together 
with the rubble cliff above it has been raised in human 
times out of reach of the sea. 
rocks. The mountains of Wales are probably some 
of the oldest mountains in existence. Right away 
on the very top of Snowdon one may collect sea- 
shells. Think of the time that has elapsed to 
enable the rocks containing them to be thrust up 
into such a position! And to judge how this came 
about, we have to consider the great elevatory 
forces which are hidden from our view. The 
cooling of the crust has caused in the past whole 
masses, almost whole continents, to slide as though 
they were ina liquid condition. Nothing is so 
solid that it cannot under sufficient pressure be 
made to flow asa liquid. In Scotland these very 
early formations have been sometimes doubled into 
such folds that older rocks have been pushed, for 
miles, over younger rocks. In the coalfields of 
France and Belgium older Silurian rocks have been 
folded over later-formed coal-measures. Such great 
deformations cannot take place with impunity. 
Fractures take place beneath such strains, and great 
thicknesses of rock slide away from those with 
which they were formerly in contact. Faults result, and in the case of the great Northumberland 
fault, there has been a sliding of no less than five hundred and forty feet. But it is conceivable 
that many of the long-existing faults may extend right down through the whole crust, and when 
these give evidence of their existence by a further sliding, we have earthquakes as a result. The 
further movement of the well-recognized fault which runs through San Francisco caused the great 
quaking which led to such disastrous results to that city. 
Our coloured illustration will give a better general idea of all the sedimentary formations than 
Photo by} [E. A. Martin, F.GS 
One side of a mountain one thousand feet high has - 
been gouged out to supply slates of Cambrian age, at the 
Penrhyn quarries, North Wales. The worker is here seen 
shaping the slates. 
could possibly be given in a few words. Above the 
Silurian we pass to the Devonian, with its beautiful 
limestone corals, and its Old Red Sandstone 
equivalent elsewhere, with its wonderful develop- 
ment of armour-plated fishes. Then we see the 
next phase, in which over wide areas of the earth’s 
surface thick forests of lowly-organized tree life 
flourished, whose decay has furnished us with our 
coal-supplies. Above these we have the two New 
Red Sandstone formations, the Permians and the 
Trias, in which frequently desert conditions are 
portrayed, and from which our rock-salt supply is 
principally derived. In the next age we are intro- 
duced to the world-wide dominion of the reptiles, 
of which the Lias Clay has furnished abundant proof. 
We have the dominion of the air conquered by the 
flying reptiles, whose wing-membranes gave a spread, 
in some cases, of several feet, whilst at the height 
of their power, the earliest true bird appeared, a 
menace to the power of the reptiles. Up through 
the oolites, we have constant types of life appearing 
