170 Prof. O. P. Hubbard on Erosion in New Hampshire. 
The examination of the valleys of the state of New York, as 
at the Little Falls, &c., and of its lakes in different parts, shows a 
difference ¢ level and a depth of erosion of 1200 feet to 2000 
fe o the observations on the sandstone of the Connecti- 
cut ss i in > Maneataleks and Connecticut, indicate its erosion 
to the extent of 1200 feet. This erosion of the sandstone is only 
consistent with a similar one in the northern portigns of New 
England, and requires its occurrence if we would provide the 
constituents of the sandstone in the first place and its continu- 
nee and increase subsequently. Whether this result is refera- 
ble to one period or another is not now a question 
The following facts are cited from the Report of the Geology 
of New Hampshire, to sustain the general proposition, and which 
is also strengthened by the evidence afforded by metallic veins in 
positions similar to that of the trap. 
The Lower Patuccoway Mountain of syenite in Notting-. 
ham is cut, through its summit, into two nearly equal parts by a 
dike of columnar greenstone trap from six to twelve inches wide, 
and which can be traced for a quarter of a mile till conaeales by 
the soil. This mountain is 780 feet high above the s 
2. In Piermont the mica slate is intersected by numerous dikes 
of greenstone trap; and from Piermont to Haverhill Corner, nine 
dikes are found, some of them porphyritic, and one so filled with 
magnetic iron pyrites as to affect the compass. 
3. Red Hill, of syenite, and 2000 feet above the level of the 
sea, is crossed at abont one-third its height by a large dike of 
porphyritic trap, N. 30° W. 
4. On the declivity of the westerly peak of Gunstock Moun- 
tain, which is 1561 feet above lake Winipissiogee, is a vein of 
magnetic oxyd of iron, the pieces of which have polarity, and 
arge dikes of trap occur on the southerly pea 
5. Baldface Mountain, in Jackson, of granite, is cut through its 
midst by a few trap dikes, and ata height of 1404 feet above its 
base, and in other places is cut by veins of peroxyd of iron of 
great width, which are traced down its flanks. 
6. Several trap dikes in Jackson contain carbonate of lime, and 
cut through mica slate, granite and a granite vein, one of which 
is fifty feet wide. 
. At Aaigaayed Falls, and on to the sea, the hard flinty rock is 
cut by dikes of t 
8. In Eaton, dikes of porphyritic trap from ten to sixteen feet 
wide cut through a hill of granite, and sgn in another place a 
ae ike four feet wide cuts a hill of gran 
n the east flank of the White oan on the Pinkha 
Soa in Jackson, the mountain ledge of mica and chiastolite Hp 
1. p.50. os Wands pe Tekh, 78, 79 —6. p.80.—7. p. 93.— 
8. on 96, Gouge a? P- p. pp. p- i. p 
