Elizabeth Cary Agassiz, Louis Agassiz: his life and correspondence, third edition

[464] his arrival in the United States, but nowhere had he found them in greater distinctness than on the shores of Lake Superior. As the evidence accumulated about him, he became more than ever satisfied that the power which had modeled and grooved the rocks all over the country, and clothed it with a sheet of loose material reaching to the sea, must have been the same which had left like traces in Europe. In a continent of wide plains and unbroken surfaces, and, therefore, with few centres of glacial action, the phenomena were more widely and uniformly scattered than in Europe. But their special details, down to the closest minutiae, were the same, while their definite circumscription and evenness of distribution forbade the idea of currents or floods as the moving cause. Here, as elsewhere, Agassiz recognized at once the comprehensive scope of the phenomena. The whole history reconstructed itself in his mind, to the time when a sheet of ice clothed the land, reaching the Atlantic sea-board, as it now does the coast of Spitzbergen and the Arctic shores.

He made also a careful survey of the local geology of Lake Superior, and especially of the system of dykes, by the action of which