Page:The Journal of geology (IA journalofgeology11893univers).pdf/348

of Harvard, by saying: "But I have not yet seen a trace of glacial action proper, if polished surfaces and scratches and furrows are especially to be considered as such."^[1]

Thus far I have confined myself to a statement of the facts that relate directly to glaciation. Aside from these a matter of the utmost importance is the continuity of life from Tertiary times down to the present, especially in the tropical and subtropical parts of the earth. If glaciation had been cosmic, as suggested by Agassiz—if it had taken place under the very equator—then the reasoning of biologists regarding the origin and distribution of the present life of the globe is about all at fault. A reviewer of Hartt's Geology of Brazil long ago called attention to the fact that "the grand objection to the theory of the former existence of a continental glacier in tropical America, is the unbroken continuity of tropical life since the close of the Tertiary period."^[2] Mr. Wallace, in an earlier review, had already called attention to the same point,^[3] while still another lays stress upon the important fact that the plants found in the Amazonian silts, supposed by Agassiz to be of glacial origin, are the remains of tropical plants, and are not therefore comparable with the Alpine plants growing beside existing glaciers in mountainous regions.^[4]

The following are some of the opinions of geologists regarding the phenomena regarded by Agassiz and Hartt as glacial. These authors are quoted, not simply for the purpose of bringing the weight of authority to bear on the subject, but because they have all seen much of the geology of Brazil and are competent to have opinions worthy of consideration. Darwin, who visited Brazil in 1832 and saw something of these