west. This river continued almost through the middle of what is now Lake Erie, and opposite where Sandusky is now situated divided itself into two branches, which still exist in the Maumee and the Detroit. The Laurentian continued northward close along the southern shore of Georgian Bay, turned southward to the centre of the Lake Huron basin, where the Huronian River, sweeping across central Michigan, joined it from Saginaw Bay. The Laurentian itself passed northward through the Straits of Mackinaw and terminated in what is now Lake Michigan. The story of this vast water system has been left in clearly defined outlines; its indelible marks are ancient valleys, sand-filled channels of the great streams, and worn escarpments. Seldom has science had an easier story to read of ages that are gone. Then came the second step in the creating of the Lakes of to-day. Slowly life changed as the Glacial Age approached, and with the sweeping back of life the rivers, too, passed out of existence. During the slow passing of centuries, their channels were filled, and the valleys were obstructed with drift, so that when the Ice Age had come and gone their channels no longer ran clear and unobstructed to the sea. As a consequence, great areas were submerged, and hundreds of thousands of square miles of what is now fertile land, populated by millions and dotted by cities, became an ocean. But the continent was still in process of formation. The land in the Lake region began to rise, and continued in its elevation until out of the chaos of sea the Lakes were formed. To the north-east, as the centre of the continent rose, there was a tilting of the land oceanward, and this warping dropped Lake Ontario below the level of the other Lakes, thus interposing a barrier to free communication to the sea and giving birth to Niagara Falls. In this way, so far as science can tell, the Great Lakes of to-day were brought into existence. How early human life existed along their shores it is impossible even to guess, but that the earliest life of the continent should first of all gather in the valleys of the vast water system that gave them birth, and afterward reassemble along their shores, is highly probable. The earliest discoverers to penetrate into the wildernesses of the West found these shores inhabited by powerful nations. Other nations were facing extermination. Still others had ceased to exist and were forgotten except in legend. Along the Inland Seas have been found evidences of a superior race to the warlike aborigines of the days of La Salle. But only these evidences, utensils of copper and stone and clay, remain as proof of their existence. What they were, when they lived, and how they died, is one of the mysteries that will remain forever unsolved.