Now, it appears that all these various characteristic marks of glacial operations can be distinctly traced in many countries where the action of moving ice has been unknown within the period of history. And on this fact is founded the Geological theory of an ancient Glacial Period. We are confidently assured that a great part of Northern Europe, including even our own islands, not to speak of America and other countries as well in the northern as in the southern hemisphere, were, in some far distant age, the scene of those same phenomena which are witnessed at the present day amid the solemn grandeur of the Alps, and in the frozen wastes of the Arctic regions. In that age enormous Glaciers moved slowly downward from the snow-clad heights over innumerable valleys now rich with the fruits of the earth; ponderous Icebergs floated over wide areas of the ocean, where now the dry land appears; and vast piles of promiscuous rubbish, with great angular blocks of stone, were deposited on the slopes and crests of submarine mountains that now tower hundreds of feet above the level of the sea. To illustrate this theory, we would begin with a country where the vestiges of glacial operations in past times may be studied side by side with the glacial phenomena of the present day. In Switzerland it needs but little skill to discern many marks and tokens of moving ice where moving ice is no longer found. In descending, for example, the valley of the Hasli or the valley of the Rhone, the intelligent traveller can hardly fail to observe how the rocks all around are scarred and furrowed, precisely after the same fashion as the rocks in the higher parts of the same valleys are now being scarred and furrowed by the Glacier of the Aar and the Glacier of the Rhone. At intervals, too, may be seen long mounds of unstratified gravel and mud, with large fragments of rock, in every way resembling the terminal moraines now daily accumulating at the extremities of existing Glaciers. When these facts are once distinctly brought home to the mind, it is impossible to resist the conclusion that several of the Alpine Glaciers once extended far beyond their present limits down the valleys of Switzerland.