176 
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 Deposirs IN New Hampsuire. (DrirFt, 
QuATERNARY, PosT-PLIOCENE, PLEISTOCENE.) 
FORMATIONS, AND THEIR SoH ONCE. peace: 
DISTRIBUTION. 
Lower till, p. 9, 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. ro and rox. 
Till; ground-moraine; glacial, 
unmodified, or unstratified drift; 
boulder-clay ; hardpan. 
Characterized, p. 9, by its glaciated 
stones, its dark and usually bluish 
color, and its compactness and hard- 
ness. Formed, pp. 5 and g, by long 
continued wearing and grinding, be- 
neath the moving ice-sheet ; overly- 
ing rounded and striated ledges, pp. 
4and 5, 
intercalated clay and sand, 
pp. 6, 17, and 18; about Winni- 
piseogee and Squam lakes, fre- 
quent, varying in thickness up 
to 30 feet, pp. 131-137; else- 
wrPrSy rare, pp. 108, 163, and 
164. 
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. 
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 
was interrupted by a readvance of the 
ice, p. 163. 
Upper till, p. 10, found 
throughout the state, p. 4; thick- 
ness, usually less than ro feet, 
but varying up to 20 feet or more. 
By many writers not distinguish- 
ed from lower till, both being in- 
cluded as till, glacial drift, or boul- 
der-clay. 
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- 
ehects and deposited when this melt- 
ea. 
Kames, 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. 
Merrimack series, pp. 84-93. 
Ossipee series, pp. 144-149. 
Andover, Mass., series, pp. 
167-170. 
Haverhill, Mass., series, p. 
170. 
Connecticut series, pp. 43-48. . 
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. 
Deposited, pp. 13 and 14, by gla- 
cial eee 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 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 
roo feet, pp. 155-164, 170 and 
171. 
Nore, The valley drift, kame- 
like plains and broad ridges, kames, 
and intercalated clay and sand, are 
all embraced under the title »zodz- 
fied drift, which is defined at the 
top of p. 4. 
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. 
Valley 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 are rem- 
nants of flood-plains which were 
annually overflowed at the end 
DEPOSITED DURING THE CHAMPLAIN PERIOD, p. 11. 
ing in height up to 200 feet above 
| the present streams. 
| of the Champlain period, vary-- 
The blue and gray clay, pp. 94, 
» 153-155, and 158-rx6r, are proba- 
biy equivalent to the Champlain 
clay in Vermont, the Leda clay in 
Canada, and the Erie 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. 
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. 
