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The periods are lesser divisions of the eras. In the Proterozoic, there are two periods, viz.: the Archaean and the Algonkian. The Paleozoic has six periods, viz.: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian.
When the others arrive the packs, etc., are taken across in three loads. The four of us go over in the last load. Scramble up the Archaean by myself and sit in the shade, near the shelter tent, until I am put on the burro Joe and started off with the doctor. Back at Bass Camp.
Upheaval is the one constant and clearly recognisable feature associated with, or preceding, ice-ages. We saw this in the case of the Cambrian, Permian, Eocene, and Pleistocene periods of cold, and may add that there are traces of a rise of mountains before the glaciation of which we find traces in the middle of the Archaean Era.
He says that such great progress has been made in his science the science of the chemical processes in living things that "their cryptic character seems to have disappeared almost suddenly." On the strength of this new knowledge of living matter, he ventures to say that "a series of lucky accidents" could account for the first formation of living things out of non-living matter in Archaean times.
That is a familiar principle in our industrial world to-day, and we shall find it illustrated throughout our story. We therefore find the various processes of evolution, which we have already seen, now actively at work among the swarming Archaean population, and producing several very distinct types.
It is more pertinent to inquire how the higher classes of animals, which we found in the Cambrian seas, can have arisen from this primitive worm-like population. The struggle for life in the Archaean ocean would become keener and more exacting with the appearance of each new and more effective type.
Below this is found the Archaean rock. It is hard for any but the well-trained observer to realize that practically the same conditions that exist on the north wall, exist on the south wall, directly under his feet, except that the Algonkian is absent. The talus shuts off the view, and it seems impossible that there can be such great precipice walls as the opposite mural face reveals.
No one can travel there without becoming tiresomely familiar with fine-grained, shattered schists, coarse granites, and their curiously banded relatives, the gneisses. This rocky highland stretches from a little north of the St. Lawrence River to Hudson Bay, around which it laps in the form of a V, and so is known as the Archaean V or shield.
We pass through, and on the other side stand before the shattered Tonto sandstones that Thomas Moran, years ago, named the Temple of Set, and even further on, where we used to leave the horses and climb down a boulder, and up the face of the cliff, and down the rope ladder over the archaean rocks here a crystalline mica schist and so on, all the way to the river.
One may approximately estimate the various strata of the wall of the Kaibab as follows: Colorado River, say. . . 2400 feet above sea level Archaean . . . . . . . . 1000 " thick Algonkian . . . . . . . 1100 " " Cambrian . . . . . . . . 1000 " " Carboniferous . . . . . 2750 " " Total level above sea. . 8250 Bass Tomb or Holy Grail Temple. The great north wall is not featureless.
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