Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 edition. Excerpt: ... coarse gravel, which would in some places be lodged in ice channels, in others spread out over masses of ice. Finally, as the last masses and the lowest stratum of ice melted, the gravels thereon would settle down from the ice (as dirt does from snow-drifts in the spring) into the irregular forms in which we find these ridges. Hagget's Pond doubtless marks a depression where the ice lingered while a kame-stream deposited in a temporary lake the sand plains to the south towards Tewksbury. Pomp's Pond was preserved from filling up by a similar mass of ice. The " kettle holes " near Pomp's Pond, and in the plain at Ballardvale, mark places where smaller masses of ice were covered up by the sand and gravel. When the ice melted, a hole would be formed without any outlet. The basin of Great Pond in North Andover was formed in a different manner. In this case the lake is hemmed in by lenticular hills, one of wh ch partially dams its natural outlet. Lenticular hills have also in many places below North Andover determined the course of the Merrimack River. Thus it appears that the citizen of Andover does not need to go to Switzerland, nor to Greenland, to study glacial phenomena. But he may enjoy that privilege to his heart's content among his own hills and gravel deposits. A most instructive portion of the skeleton of a continental ice sheet is spread out before his own doors. It is in gravels contemporary, in the period of their deposition, with the formation of Indian Ridge, that the palaeolithic implements of northwestern Europe and eastern North America, especially in Trenton, N. J., are found. It is not improbable that the peat bogs, and "kettle holes," and ponds of Andover may furnish material aid in determining the antiquity of the...
