Abstract
II. FOR reasons which I will explain presently, I would mention especially pebbles of a red porphyry, and others of a green compact epidote, as common in the Port San Antonio formation. The position of the Bay of San Mathias, its great length, and more particularly the depression or denudation at Port San Antonio, suggest the probability that the Rio Negro once poured its waters into this large gulf instead of opening directly into the ocean. I should add that while erratic pebbles occur in such abundance at San Mathias Bay, there are no hard rocks in place upon which the peculiar marks of glacial action could be perceived. Nor would these stratified banks of pebbles, even though unquestionably connected with the drift, afford in themselves any unmistakable evidence of glacial derivation.
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AGASSIZ, L. Professor Agassiz's South American Expedition* . Nature 6, 229–231 (1872). https://doi.org/10.1038/006229a0
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DOI: https://doi.org/10.1038/006229a0