. The geology of New Hampshire : a report comprising the results of explorations ordered by the legislature. ery plain marks at right angles to those beneath. I was able topreserve only a piece of this boulder, showing the upper surface and thebeginning of the lower strias at right angles to them. The boulderproved larger than was expected, so that I could not transport it entireto Culver Hall. A common variation in shape is the elongated narrow one, a prolatespheroid. Geikie, in his work on the Great Ice Age, figures four striatedstones from Scotland, three of which clearly possess the typica
. The geology of New Hampshire : a report comprising the results of explorations ordered by the legislature. ery plain marks at right angles to those beneath. I was able topreserve only a piece of this boulder, showing the upper surface and thebeginning of the lower strias at right angles to them. The boulderproved larger than was expected, so that I could not transport it entireto Culver Hall. A common variation in shape is the elongated narrow one, a prolatespheroid. Geikie, in his work on the Great Ice Age, figures four striatedstones from Scotland, three of which clearly possess the typical shape Ihave mentioned, while the fourth is blunt at one end and pointed at theother,—a form also seen with us. These stones show the same featuresthe world over. Argillaceous boulders best preserve the glaciation. Surface Deposits at Portland, Me. The relations of the two varieties of till to the Champlain gravels arenot exhibited in any outcrops yet discovered in New Hampshire. Afamiliarity of long standing with the fossiliferous clays and the drift of ^;^^^^^^^^^^^&mM 3> =¥^-,,=?.-Xs ^^.V^. Fig- 59-—Section in Till, Portland. a. Upper till; b. Fossiliferous Champlain beds; c. Lower till. Portland, Me., led me to think the question of relative position wellshown there; and upon examination I discovered that the fossiliferousbeds occupied a place midway between the two kinds of till. Numerousexcavations have made the sections in the till and sands perfectly satis- 28o SURFACE GEOLOGY. factory, so that the mutual relations of the three deposits, as displayedin Fig. 59, may be regarded as fixed beyond controversy. The massivebeds overlie the lower till, and are covered by the upper till. Thesefacts indicate the deposition, first, of the ferrous glaciated till; second,its submergence to at least 100 feet below the present level; third, thereadvance of the ice-sheet so as to cover the Champlain beds; fourth,the melting of the ice, and the falling down of the debris held i
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