| ON NEW ENGLAND AND THE UPPER MISSISSIPPI BASIN IN THE GLACIAL PERIOD.[1] |
By Prof. JAMES D. DANA.
SINCE the publication, in this Journal, of Prof. G. F. Wright's paper on the Unity of the Glacial Epoch, nearly a year since,[2] this subject has been much discussed in the scientific journals of the country, and with some interesting developments besides those within the purpose of the writers.
1. It has been shown that there are good working geologists on each side of the question.
2. It has been made manifest that the advocates of unity are mainly the geologists that have investigated Eastern glacial regions in the country, and especially New England, while the advocates of two Glacial epochs are chiefly those whose glacial studies have been in more western regions.
The writer, who has thus far taken no part in the recent discussion, here states that he has found in his geological explorations, which have been extensive over New England, the State of Maine excepted, no facts that require for their explanation an appeal to two Glacial epochs, and none that has even suggested the idea.
3. The presentation of arguments on the side of unity has been moderate in tone and free from dogmatism. Among geologists on the other side, great confidence in the obvious facts has given occasion to expressions almost of accomplished triumph for the two-epoch theory.
4. Among the prominent glacial investigators, one has been on both sides of the question. Having studied glacial phenomena long and faithfully in New England, Warren Upham explained the facts which he had observed on the theory of one advancing and retreating glacier, and found evidence of its terminal moraine and another halt moraine in the islands south of New England and on part of the adjoining mainland. But after some years of study in Minnesota and the neighboring States and over the region northward through Manitoba, he adopted the theory of two Glacial epochs. Returning again to New England and revising the facts there presented, he was led back to his former opinion, as he has announced in his recent papers. Since no geologist in America is better acquainted with the facts on the two sides, or more faithful and earnest in glacial investigation, these changes in his conclusions have special interest.
