. The geology of New Hampshire : a report comprising the results of explorations ordered by the legislature. n Bedford to Reeds Ferry. This side of the val-ley appears to have been specially subjected to the erosion of the river,which has in many portions removed nearly every trace of modified drift,leaving the till or ledge sloping to the present channel. The till is fre-quently exposed in the banks or bed of the river between Manchesterand Nashua, and also sometimes appears on the surface of the extensiveplains, showing that the modified drift has not so great a depth as in thewidest portion
. The geology of New Hampshire : a report comprising the results of explorations ordered by the legislature. n Bedford to Reeds Ferry. This side of the val-ley appears to have been specially subjected to the erosion of the river,which has in many portions removed nearly every trace of modified drift,leaving the till or ledge sloping to the present channel. The till is fre-quently exposed in the banks or bed of the river between Manchesterand Nashua, and also sometimes appears on the surface of the extensiveplains, showing that the modified drift has not so great a depth as in thewidest portions of this valley northward. Nearly opposite Goffs Falls,and on Sebbins brook at the south line of Bedford, the alluvium expands,forming three terraces, the highest in each case being 90 feet above theriver. Plate Y. ^ SHOWING the Modified Drift of Merrimack, CoNToocooK,andAshuelot Rivers. SCALE OF MILES Explanation. -^-^ Hdife of GlacialJDnfl -^ / BoimiuyMhTen lernicei, Grm el ridoes, orhamci,, «.«.^Tiicient tifverhedf, i i with ^-^^^^IVt/ures denote JieU/htsmjecl uhove the sea. ^. ^^isij MODIFIED DRIFT ALONG MERRIMACK RIVER. 97 In Litchfield and Merrimack the high sandy plains have a larger devel-opment than in any other portion of this valley excepting Concord. Onthe east side we find the modified drift occupying almost the entire town-ship of Litchfield. An area from one fourth to three fourths of a milewide next to the river is the low fertile terrace,—which is partly interval,as opposite the mouth of Souhegan river, but mostly lies somewhat abovehigh water. East of this is the plain, about lOO feet above the river, co-inciding in its eastern boundary nearly with that of the township. Itsgreatest width is opposite Thorntons Ferry, where it extends three milesback from the river. Its surface is in general very level; a depression ispartly occupied by Darrah, Halfmoon, and other ponds. This widealluvial area becomes narrowed to two thirds of a mile af
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