LESSON II.

THE FIRST CONTINENT.

“As he who sets his willing feetIn Nature’s footprints light and fleet,And follows fearless where she leads.”

“As he who sets his willing feet

In Nature’s footprints light and fleet,

And follows fearless where she leads.”

—Longfellow,Keramos.

For convenience in study, scientists have divided the story of earth-building into vast epochs, known as times. The times are again divided into ages. At first the names used for these times were derived from the Latin, and simply meant first, second, third, and fourth times.[3]The first time or period was that in which dry land first appeared above the waters. The fourth time meant the period during which mammals, fruit, grain, and man appeared. The second and third periods or times of course divided the interval between these two.

Other names, made from Greek words, are now coming into general use to represent these building periods.[4]If weput these new names into plain English, they mean the time of first life, or first living things,—the age of ancient life, when most of the fossils, or petrified plants and animals which we now find, were buried up in the rocks; then the middle time; and finally the “new time,” when man and most of the plants and animals that now belong in the world appeared. Such long hard names make the beginning of science seem dry and dull, but we must not be alarmed: a very beautiful garden has sometimes a rough and ugly gate.

LOOKING FROM AFAR.

Theagesinto which thetimeswere divided have their names either from what was produced in them, or from thepart of the world where their rocks chiefly appear on the present surface. Thus the Carboniferous age is the carbon or coal age, because then most of our coal-beds were formed. The Silurian age, on the other hand, takes its name from a part of Wales, where its rocks are most conspicuous, and in this part of Wales a people called Silures used to live. A study of the “Table of Earth-building,” which is the frontispiece of this book, will show clearly these times and ages.

It is concluded that the first land which appeared was a range of rocks, which is best known in the valley of the St. Lawrence River, and represents the oldest land on the globe. We need not fancy that the new continent occupied a large part of the globe; it was comparatively very small. Neither can we look for it to-day, and find it as when it rose over the hot ocean. The first land of the world lifted above the waters and sank again, and so rose and sank more than once or twice in great lapses of time. This rising and sinking was caused by the action of heat and steam in the interior of the earth, which elevated and rent the crust.

From Labrador to Lake Superior the old Laurentian rocks crop out. If you go to the Adirondack Mountains, you stand on the first continent, though it is now covered with a soil which did not exist in that early time of its uplifting. There are spots of this old continent in Nova Scotia, New Brunswick, Sweden, Norway, Bavaria, and the Hebrides. These are then, the oldest parts of the world, and you could take your atlas, and by sketching a continent, long, narrow, and crooked, that would cover these places with a few outlying islands to help it out, you would have a fair idea of the first continent.Probably nothing grew on it, but in the sea there were some plants and animals.

The beds of Laurentian rocks in North America are sometimes thirty thousand feet thick. These early rocks, more than any others, show the action of great heat. The action of heat has changed the rocks from their first condition. Time and heat will turn sand, lime, and clay into crystal and marble.

For a long time the Laurentian age was supposed to have been wholly destitute of any life, and was called the azoic, or life-lacking time. But Sir William Dawson, after long explorations among the Laurentian rocks, found in them the fossil remains of a once living creature. He named this creature the Dawn Animal, or Eozoön. The name suggests that this is the most ancient animal yet discovered, and represents the dawn of life on our planet.

What was this Dawn Animal like? So far as can be judged from the fossil, it was a very large creature, soft and gelatinous like a jelly-fish.[5]It had a stem by which it was fastened to the bottom of warm, shallow seas. Thus it never moved from its place, but swayed with the moving waters, and perhaps had the power of expanding and contracting itself. Like the mollusks,[6]the Eozoön wanted a house for its delicate body. Therefore, as it swayed to and fro, it collected from the water carbonate of lime, and covered itself with a thin shell or crust. As it continued to grow it continued to cover itself with crust after crust of lime. This lime crustwas not a solid mail over Eozoön; it was rather like a fine net or sieve through the pores of which could pass the jelly-like threads or filaments whereby the creature collected lime and food. But here we are led to another discovery. If the Eozoön was a living animal, it must have had food to nourish it, and living creatures feed upon animal or vegetable substances.[7]Therefore in these warm seas there must have been minute animal or vegetable organisms which Eozoön could gather with its long nets or lines, as it grew at the bottom of the sea. Was the Eozoön beautiful? We cannot speak positively; but as we find no age of the world when there was not beauty of form and color, as we see beauty often followed as an end in creation, we may suppose that the Eozoön had gay colors and looked like some great vivid flower waving upon its stem in the water.[8]

There are beds of limestone in the Laurentian rocks, which bear indications of former animal life. Also in the Laurentian rocks there are beds of iron ore, and these have been supposed to indicate that there was some vegetation in the Laurentian period. Now as in the Laurentian period the Eozoic age shows us vast beds of iron, graphite, and limestone, we may suppose that there were in the warm waters of that era great beds of eozoön like the coral reefs of to-day. In the deep seas of the present age there are myriads of little creatures called foraminifera; and though we have found no trace of these in the earliest rocks, it may be thatthe first ocean swarmed with them and that they were then busy building limestone strata just as they are busy now.

During the Eozoic age the warm, turbid ocean that nearly covered the globe constantly deposited sediment, and at last the thin earth-crust gave way under the strain and weight upon it. The earth-crust collapsed, or fell in, as a great floor which has been overburdened. We sometimes hear of the floors of large rooms which give way under some heavy strain. If we go to see a place where such an accident has occurred, we shall notice how flooring and timbers do not fall flat, as a whole, but are crushed and crowded together sidewise or edgewise. When the Laurentian continent sank, many of its ranges and beds of rock were bent and tilted in this fashion, and we so find them to-day.

How long was this first or Eozoic period? That, no one can tell. If we should try to tell, we should merely use numbers so great that, as applied to years, we cannot imagine them. The Dawn age seems a very good name for it, as it was the age of the earliest continents, and of the first animal and vegetable life. As the study of the earth goes on, and other and deeper-lying rocks are examined, we may learn much more about this first world-building period. Now, as we look far, far back to it, it strikes us, I think, chiefly as distant, barren, silent. If we had been Afrites, and hovering over that early continent, I think we should not have heard a sound, except the lap of the warm waves on the rocks; we should not have seen a living thing. But if instead of Afrites we had been Pixies, or water-sprites, we should havegone down into the waters of that wide, warm sea, and what should we have found? We can as well fancy ourselves Pixies as Afrites. Let us fancy ourselves in those seas. I think we should have seen sea-weeds, fine and small, but of many curious shapes, and millions of creatures with and without shells, some large, some small, tinted like rainbows, and lively and happy in their water-world.

FOOTNOTES:[3]Primary, Secondary, Tertiary, Quaternary.[4]Eozoic, Paleozoic, Mesozoic, Cenozoic.[5]Nature Reader, No. 2, Lessons 36 and 37.[6]Nature Reader, No. 1, Lesson 37.[7]Nature Reader, No. 3, Lesson 1.[8]And after all so few and indefinite are the traces, that Eozoön may not have been an animal form at all, but a merely mineral structure.

[3]Primary, Secondary, Tertiary, Quaternary.

[4]Eozoic, Paleozoic, Mesozoic, Cenozoic.

[5]Nature Reader, No. 2, Lessons 36 and 37.

[6]Nature Reader, No. 1, Lesson 37.

[7]Nature Reader, No. 3, Lesson 1.

[8]And after all so few and indefinite are the traces, that Eozoön may not have been an animal form at all, but a merely mineral structure.

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