Wonders of Earth, Sea and Sky | Page 8

high up in the cliffs around our land in many
different places.
They had at first a theory that the sea must once, in far back ages, have
been a great deal higher than it is now. But this explanation only
brought about fresh difficulties. It is quite impossible that the level of
the sea should be higher in one part of the world than in another. If the
sea around England were then one or two hundred feet higher than it is
now, it must have been one or two hundred feet higher in every part of
the world where the ocean-waters have free flow. One is rather puzzled
to know where all the water could have come from, for such a
tremendous additional amount. Besides, in some places remains of
sea-animals are found in mountain heights, as much as two or three
thousand feet above the sea-level--as, for instance, in Corsica. This
very much increases the difficulty of the above explanation.
So another theory was started instead, and this is now generally
supposed to be the true one. What if instead of the whole ocean having
been higher, parts of the land were lower? England at one time, parts of
Europe at another time, parts of Asia and America at other times, may
have slowly sunk beneath the ocean, and after long remaining there
have slowly risen again.

This is by no means so wild a supposition as it may seem when first
heard, and as it doubtless did seem when first proposed. For even in the
present day these movements of the solid crust of our earth are going
on. The coasts of Sweden and Finland have long been slowly and
steadily rising out of the sea, so that the waves can no longer reach so
high upon those shores as in years gone by they used to reach. In
Greenland, on the contrary, land has long been slowly and steadily
sinking, so that what used to be the shore now lies under the sea. Other
such risings and sinkings might be mentioned, as also many more in
connection with volcanoes and earthquakes, which are neither slow nor
steady, but sudden and violent.
So it becomes no impossible matter to believe that, in the course of
ages past, all those wide reaches of our continents and islands, where
sedimentary rocks are to be found, were each in turn, at one time or
another, during long periods, beneath the rolling waters of the ocean....
* * * * *
These built-up rocks are not only called "Stratified," and
"Sedimentary." They have also the name of Aqueous Rock, from the
Latin word _aqua, water_; because they are believed to have been
formed by the action of the water.
They have yet another and fourth title, which is, Fossiliferous Rocks.
Fossils are the hardened remains of animals and vegetables found in
rocks. They are rarely, if ever, seen in unstratified rocks; but many
layers of stratified rocks abound in these remains. Whole skeletons as
well as single bones, whole tree-trunks as well as single leaves, are
found thus embedded in rock-layers, where in ages past the animal or
plant died and found a grave. They exist by thousands in many parts of
the world, varying in size from the huge skeleton of the elephant to the
tiny shell of the microscopic animalcule.
[Illustration: FOSSIL OF CARBONIFEROUS FERN.]
Fossils differ greatly in kind. Sometimes the entire shell or bone is
changed into stone, losing all its animal substance, but retaining its old
outline and its natural markings. Sometimes the fossil is merely the
hardened impress of the outside of a shell or leaf, which has dented its
picture on soft clay, and has itself disappeared, while the soft clay has
become rock, and the indented picture remains fixed through
after-centuries. Sometimes the fossil is the cast of the inside of a shell;

the said shell having been filled with soft mud, which has taken its
exact shape and hardened, while the shell itself has vanished. The most
complete description of fossil is the first of these three kinds. It is
wonderfully shown sometimes in fossil wood, where all the tiny cells
and delicate fibres remain distinctly marked as of old, only the whole
woody substance has changed into hard stone.
[Illustration: FOOTPRINTS FROM TRIASSIC SANDSTONE OF
CONNECTICUT.]
But although the fossil remains of quadrupeds and other land-animals
are found in large quantities, their number is small compared with the
enormous number of fossil sea-shells and sea-animals.
[Illustration: FOSSIL FOOTPRINTS.]
Land-animals can, as a rule, have been so preserved, only when they
have been drowned in ponds or rivers, or mired in bogs and swamps, or
overtaken by frost, or swept out to sea.
Sea-animals, on the contrary, have been so preserved on land