1/6 



SURFACE GEOLOGY. 



and in afterwards being partly excavated by the rivers in the process of 

 deepening their channels. 



A table is added, showing the formations which have been described 

 in this chapter, arranged in the order of their deposition, beginning with 

 the oldest. 



Glacial and Champlain Deposits in New Hampshire. 

 Quaternary, Post-Pliocene, Pleistocene.) 



(Drift, 



formations, and their 

 distribution. 



Lower till, p. g, deposited during 

 the glacial period, pp. 4-11 ; found 

 throughout the state, p. 4 ; often ac- 

 cumulated within 25 miles from the 

 coast, and rarely farther inland, in 

 massive, oblong, rounded hills, 50 to 

 200 feet high, pp. 10 and loi. 



Intercalated clay and ^and, 

 pp. 6, 17, and 18; about VVinni- 

 piseogee and Squam lakes, fre- 

 quent, varying in thickness up 

 to 30 feet, pp. 131-137 ; else- 

 where, rare, pp. 108, 163, and 

 164. 



upper till, p. 10, found 

 throughout the state, p. 4; thick- 

 ness, usually less than 10 feet, 

 but varying up to 20 feet or more. 



Karnes, p. 12, found through- 

 out the state, the extent of series 

 varying up to 25 miles or more, 

 and the height of ridges varying 

 up to 250 feet. 



Connecticut series, pp. 43-48. 



Merrimack series, pp. 84-93. 



Ossipee series, pp. 144-149. 



Andover, Mass., series, pp. 

 167-170. 



Haverhill, Mass., series, p. 

 170. 



Kame-like plains and broad 

 ridges, pp. 17, 18,155, and 156; 

 found near the coast, about Do- 

 ver, and southward to Newbury- 

 port, varying in thickness up to 

 KM feet, pp. 155-164, 170 and 



/ 'alley drift (gravel, sand, blue 

 and gray clay, sand), p. 15; in 

 valleys throughout the state. A 

 large part of these beds has 

 been excavated by the rivers 

 during the recent or terrace pe- 

 riod, pp. 15, 16, 21, 27, and 82. 

 The highest terraces arc rem- 

 nants of flood-plains which were 

 annually overflowed at the end 

 of the Champlain period, vary- 

 ing in height up to 200 feet above 

 the present streams. 



SYNONYMS. 



Till ; ground-moraine : glacial, 

 unmodified, or unstratified drift; 

 boulder-clay ; hardpan. 



The hypothesis of Mr. Jas. Croll, 

 that an ice-sheet was accumulated 

 and melted away several times dur- 

 ing the glacial period, is considered 

 in pp. 5-9. 



By many writers not distinguish- 

 ed from lower till, both being in- 

 cluded as till, glacial drift, or boul- 

 der-clay. 



Gravel ridges ; horsebacks ; mo- 

 raine terraces; eskers, in Ireland; 

 asar, in Sweden. A list of authors 

 upon this subject is given in the 

 foot-note on p. 174. 



NoTK. The valley drift, kame- 

 like plains and broad ridges, kames, 

 and intercalated clay and sand, are 

 all embraced under the title viodi- 

 fied drift, which is defined at the 

 top of p. 4. 



The blue and gray clay, pp. 94, 

 95. '53~i55. and 158-161, are proba- 

 bly equivalent to the Champlain 

 clay in Vermont, the Leda clay in 

 Canada, and the Eric clay in the 

 basin of the great lakes. 



Deltas, above the highest normal 

 'terrace, pp. 16, 29-31, 33, etc. 



Dunes, blown upward from the 

 valley drift, pp. 17, 41, 73, and 147. 



See note in the next space above. 



Characterized, p. 9, by its glaciated 

 stones, its dark and usually bluish 

 color, and its compactness and hard- 

 ness. Formed, pp. 5 and 9, by long 

 continued wearing and grinding, be- 

 neath the moving ice-sheet; overly- 

 ing rounded and striated ledges, pp. 

 4 and 5. 



In the Lake district, deposited 

 where drainage was obstructed, in 

 hollows melted under the margin of 

 the departing ice-sheet, p. 137. Near 

 the sea-coast, the Champlain period 

 w.^s interrupted by a readvance of the 

 ice , p. 163 . 



Characterized, p. 10, by its large 

 angular boulders, its yellowish or red- 

 dish color, and the comparative loose- 

 ness of its whole mass. Contained, 

 with the modified drift, in the ice- 

 sheet, and deposited when this melt- 

 ed. 



Deposited, pp. 13 and 14, by gla- 

 cial rivers at the final melting of the 

 ice-sheet, in channels formed upon 

 the surface of the ice. When the 

 bordering ice-walls and its separating 

 ridges and masses disappeared, the 

 gravel and sand remained in long, 

 steep ridges, or in irregular short 

 ridges and mounds, enclosing bowl- 

 shaped depressions. 



Kame-like, in having been deposit- 

 ed, pp. 155 and 156, while the adja- 

 cent valleys and lowland were still 

 occupied by portions of the depart- 

 ing ice-sheet. 



Brought down by glacial rivers from 

 the melting ice-sheet, filling the val- 

 leys generally to the level of their 

 highest terraces. This deposition 

 and the subsequent formation of ter- 

 races required no submergence nor 

 change in the height and slope of the 

 land, pp. 15, 16, and 18. The height 

 of the sea in the Champlain period 

 was about 150 feet above its present 

 level, as .shown by marine shells, pp. 

 18, 165, and 166. 



