. Bulletin of the Essex Institute. Essex Institute; Natural history; genealogy. 90 BULLETIN or THE ESSEX INSTITUTE. est example of terminal moraine topography in the east- ern United States, for the reason that the underlying pre- glacial deposits have very little expression in the relief of the area. On Martha's Vineyard and in the westward ex- tension of the terminal moraine, an older topography at almost every step accentuates the height and grandeur of the morainal accumulations; whereas, on Nantucket, the approximate extent and bulk of the moraine and its posi-. FiG. 3. A portion of the i
. Bulletin of the Essex Institute. Essex Institute; Natural history; genealogy. 90 BULLETIN or THE ESSEX INSTITUTE. est example of terminal moraine topography in the east- ern United States, for the reason that the underlying pre- glacial deposits have very little expression in the relief of the area. On Martha's Vineyard and in the westward ex- tension of the terminal moraine, an older topography at almost every step accentuates the height and grandeur of the morainal accumulations; whereas, on Nantucket, the approximate extent and bulk of the moraine and its posi-. FiG. 3. A portion of the island of Nantucket, stiowing tiie frontal outwash plain with Ice-contact slope (dotted belt between twenty and sixty feet contour- lines), the fosse or depression at the head of the plain, and the kame moraine or belt of mounds and kettles of submarginal drift. The contours represent some of the larger creases on the plain. Contour interval, twenty feet. (From U. S. Geological Survey, topography by E. B. Clark.) tion with reference to the ice may be clearly discerned. (See Fig. 3.) From the existence of a terrace at the head of the sand- plain which rises from forty to fifty feet above the depres- sion or fosse on the north, it seems demonstrable that the ice-front lay along the head of the plain while deposition was taking place in the morainal tract proper. The knobs and basins moulded in the unstratified drift, then, are submarginal rather than precisely frontal in origin. In. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Essex Institute. 1n. Salem, Mass. , Essex Institute
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