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Updated: May 4, 2025
When sediments are laid down on the sea floor the materials consist of small, irregularly shaped fragments, which lie tumbled together in the manner of a mass of bricks which have been shot out of a cart. Water is buried in the plentiful interspaces between these bits of stone; as before remarked, the amount of this construction water varies.
But since their deposition these ancient sediments have been crumpled and crushed, broken with great faults, and extensively metamorphosed. The limestones have recrystallized into marbles, among them the famous marbles of Vermont; the Cambrian sandstones have become quartzites, and the Hudson shale has been changed to a schist exposed on Manhattan Island and northward.
Sun cracks show that often the outgoing tide exposed large muddy flats to the drying action of the sun. The fossils, also, of the strata are of kinds related to those which now live in shallow waters near the shore. The sediments which gathered in the mediterranean seas were very thick, reaching in places the enormous depth of ten thousand feet.
We know this was an inland sea, and had no connection with the ocean, for all the fossils and sediments deposited in it reveal that they are fresh-water organisms. In this sea, as in the earlier oceans, vast deposits of sediment were made in the early Eocene period, and another period of subsidence occurred.
At the same time, the thousands of feet of marine and freshwater sediments, with their repeated alternations of limestones, sandstones, and shales, in which the seams of coal occur, prove a slow subsidence, with many changes in its rate, with halts when the land was at a stillstand, and with occasional movements upward.
However, he did not go far enough back in time, for doubtless the Winnipeg Valley discharged southward before the last days of the "Ice Age," and the great changes in the river courses were not entirely produced by local elevation, but also by the filling of the old water channels with drift deposits and sediments.
What has taken place along the plane bef? When did the dislocation occur compared with the folding of the strata? With the erosion of the valleys on the right-hand side of the mountain? With the deposition of the sediments? Do you find any remnants of the original surface baf produced by the dislocation?
What has made the surface nn' so even? How does it come to cross the hard crystalline rocks a and the weaker sandstones b at the same impartial level? How did the sediments of c come to be laid upon it? How does the time involved in the cutting of the canyon compare with that required for the production of the surfaces mm', nn', and P?
Some of the smaller lakes are extinguished in an instant by a heavy avalanche either of rocks or snow. The rolling, sliding, ponderous mass entering on one side sweeps across the bottom and up the opposite side, displacing the water and even scraping the basin clean, and shoving the accumulated rocks and sediments up the farther bank and taking full possession.
They are soaked with water which carries in solution lime carbonate and other cementing substances. These cements are deposited between the fragments of shells and corals, the grains of sand and the particles of mud, binding them together into firm rock. Where sediments have accumulated to great thickness the lower portions tend also to consolidate under the weight of the overlying beds.
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