. The geology of New Hampshire : a report comprising the results of explorations ordered by the legislature. river, and sloping with it in the regular lines of the upper terrace, are here very interesting, as seen extending for miles up and down the valley. Nowhere else in New Hampshire is the erosion of o the modified drift, by which it pi ^ ^ has been shaped in terraces, so / ^ 700 ft clearly and convincingly display- ^. ^ „, 1 . ^ cd. Here no doubt can remam Fig. 17.—Section in Woodstock, ih miles BELOW THE MOUTH OF East BRANCH. that an Original flood-plain, ten Length, | mile. miles long,
. The geology of New Hampshire : a report comprising the results of explorations ordered by the legislature. river, and sloping with it in the regular lines of the upper terrace, are here very interesting, as seen extending for miles up and down the valley. Nowhere else in New Hampshire is the erosion of o the modified drift, by which it pi ^ ^ has been shaped in terraces, so / ^ 700 ft clearly and convincingly display- ^. ^ „, 1 . ^ cd. Here no doubt can remam Fig. 17.—Section in Woodstock, ih miles BELOW THE MOUTH OF East BRANCH. that an Original flood-plain, ten Length, | mile. miles long, has been terraced as we see it by the excavation of the river. For most of the way along *The errors which occur in Vol. I, pp. 288, 308, and 322, in stating the height of river at themouth of East Branch, and of other points in this vicinity, arose by computing barometic observations fromThornton, which, through some mistake, is given 600 feet too high by Prof. Guyot, among the usually very cor-rect altitudes published in his memoir on the Appalachian Mountain System. r:5:v Plate MODIFIED DRIFT ALONG MERRIMACK RIVER. 71 this distance, which lies through Woodstock and Thornton, we havetwo principal terraces, the higher being that just described, and thelower being wholly or in part overflowed by spring floods; but smallintervening terraces are also of frequent occurrence. All the modified drift of this valley, for the first seven miles to Wood-stock village, is niade up of gravel of different degrees of , banks and terraces of sand begin to appear; but gravel stillpredominates for a long distance below. The stream here frequentlyoccupies a broad, shallow channel, paved with pebbles of all sizes to twofeet in diameter, with little admixture of fine gravel or sand, which canacctimulate only in deep or sheltered places. Kanics. In the south part of Thornton an interesting kame of coarsegravel is found on the west side of the river, betwee
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