On the other hand, the contraction of the earth, due to the loss of its energy of rotation as well as of its internal heat, would also have proceeded more rapidly, new land would have emerged from the sea, old lands would have been submerged beneath it far less slowly than at the present day; ruptures of the crust, accompanied by earthquakes and volcanic action, would have been more frequent and thus, by the more rapid loss of its intrinsic energy, the renovation of the earth would have kept pace with its accelerated destruction. One effect of the contraction of the earth which has manifested itself in even late geological times is the crumpling up of the terrestrial crust into the sharp folds of mountain chains; but at the beginning this crumpling must have been far more universal and energetic. In this connection it is interesting to observe that the most ancient rocks known to us--the Archæan--never present themselves under any other form than as intensely plicated masses. They originally consisted of lava flows and volcanic ashes, of ancient sediments and limestones, into which subterranean masses of granite and other molten, deep-seated rocks have been injected; but under the intense pressures to which they were subjected after their formation they and the invading granite have entirely lost their original character, and have been metamorphosed into gneisses, schists, and marble, all sharply and closely folded together. In any given district the direction of their folding is maintained with wonderful constancy over great distances. There is no succeeding system of rocks that has been so completely transformed, so universally plicated, as this ancient Archæan complex. In later times we can pass from stratum to stratum of the sedimentary series and read their history almost as we turn over the pages of a book; in the Archæan all are kneaded together into a state of such desperate entanglement as to defy the powers of human ingenuity to unravel them. Thus the line of demarcation between the Archæan and subsequent sedimentary systems is the sharpest and most absolute that is known to us in the history of the earth. It marks the close of our planet’s infancy, the several events of which have passed into oblivion as profound as that of our own forgetfulness of our earliest days. Later events, on the other hand, are recorded in the stratified series with a faithfulness which increases as we approach existing times. [Sidenote: How We Know These Wonders] [Sidenote: The Ocean 100 million Years old!] [Sidenote: The Part Radium may play]