This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 edition. Excerpt: ...mass has been at least once, and probably again and again, assorted by water before it was finally taken into the ice for the last time, to be laid down in the shape in which we now find it. It therefore seems to me that we are justified in supposing the horizontal dispersion of the materials contained in the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 edition. Excerpt: ...mass has been at least once, and probably again and again, assorted by water before it was finally taken into the ice for the last time, to be laid down in the shape in which we now find it. It therefore seems to me that we are justified in supposing the horizontal dispersion of the materials contained in the boulder train from Iron Hill to have been mainly brought about by the violent movements of subglacial water. Attention has already been called to the fact that the fine debris derived from the scoring and polishing of Iron Hill, and from the comminution of the boulders which are plucked from it, is not distinctly recognizable in the path of the boulder train. The evidence of wearing afforded by the hill itself deafly shows that at least three fourths of the erosion which took place upon its surface delivered the iron ore to the glacier in the form of fine sand, such as is ground out from glacial striations or worn from the polished surfaces between the grooves. Moreover, by far the greater part of the mass of the erratics which were plucked from the rock was reduced to a similar state of division by the attrition to which the fragments were subjected. If this iron sand had been transported in substantially the same manner as the larger boulders, we should be entitled to expect evidence of the material in the path of the trail; but, as before noted, this comminuted magnetite is scarcely, if at all, more abundant in the field occupied by the boulders of the substance than in the other parts of the country to the north, east, and west of the train. The only way in which I can account for the disappearance of the fine de'bris is by supposing that it was borne away to a considerable distance by the subglacial currents of free water. Although...
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All Editions of The Conditions of Erosion Beneath Deep Glaciers Based Upon a Study of the Boulder Train from Iron Hill, Cumberland, Rhode Island (1893)
