ace of the earth with the
exception of a few isolated portions lifted above the almost universal
ocean, how monotonous must have been the conditions of life! And what
should we expect to find on those first shores? If we are walking on a
sea-beach to-day, we do not look for animals that haunt the forests or
roam over the open plains, or for those that live in sheltered valleys
or in inland regions or on mountain-heights. We look for Shells, for
Mussels and Barnacles, for Crabs, for Shrimps, for Marine Worms, for
Star-Fishes and Sea-Urchins, and we may find here and there a fish
stranded on the sand or strangled in the sea-weed. Let us remember,
then, that in the Silurian period the world, so far as it was raised
above the ocean, was a beach; and let us seek there for such creatures
as God has made to live on seashores, and not belittle the Creative
work, or say that He first scattered the seeds of life in meagre or
stinted measure, because we do not find air-breathing animals when there
was no fitting atmosphere to feed their lungs, insects with no
terrestrial plants to live upon, reptiles without marshes, birds
without trees, cattle without grass,--all things, in short, without the
essential conditions for their existence....

I have spoken of the Silurian beach as if there were but one, not only
because I wished to limit my sketch, and to attempt at least to give it
the vividness of a special locality, but also because a single such
shore will give us as good an idea of the characteristic fauna of the
time as if we drew our material from a wider range. There are, however,
a great number of parallel ridges belonging to the Silurian and Devonian
periods, running from east to west, not only through the State of New
York, but far beyond, through the States of Michigan and Wisconsin into
Minnesota; one may follow nine or ten such successive shores in unbroken
lines, from the neighborhood of Lake Champlain to the Far West. They
have all the irregularities of modern seashores, running up to form
little bays here, and jutting out in promontories there....

Although the early geological periods are more legible in North America,
because they are exposed over such extensive tracts of land, yet they
have been studied in many other parts of the globe. In Norway, in
Germany, in France, in Russia, in Siberia, in Kamchatka, in parts of
South America,--in short, wherever the civilization of the white race
has extended, Silurian depo