Mineralogy and Geology of the White Mountains. 107 
is one anda half inches, and the western, four to six inches wide, 
and they become, as suggested above, at the distance of some 
twenty rods north, one larger dike. Fig. 2. 
The occurrence of the two veins in the field, after one had 
seemed to terminate, and the change of the’ vein of greater di- 
mensions from the eastern to the western side, are only some of 
the phenomena frequently observed in trap dikes, several of 
which will hereafter be mentioned 
No. 3. A short distance west of No. 2, crosses the road, direc- 
tion N. E. and S. W., two feet wide, color very dark, not por- 
hyritic. 
Trap Dike in Wentworth. 
On the road from Orford to Plymouth, one mile west of Went- 
worth, above the saw-mill on Baker’s creek, is a trap dike in granite, 
on the left hand close to the road, course north, ten feet wide, 
color dark gray, and even black, very fine grained and compact 
in some parts, and fracture smooth ; in others, amygdaloidal, and 
contains nodules of chalcedony, and numerous very small round 
white spots of zeolite, which, from its pearly lustre, foliated 
structure, and low degree of hardness, is, I think, stilbite. Where 
the surface of the rock is weathered, the stilbite is decomposed, 
and the cavities are empty. 
Darker specimens strike fire with steel, and all give, when 
aoe upon, an argillaceous odor, most striking in the softer 
imens. 
Half a mile S. E. of Wekdoai: by the roadside, are frag- 
ments of red feldspathic granite, lying on granite in situ, with a 
very hard, compact trap, adhering to them, but no dike was ob- 
served. 
Tourmalines and Diluvial Scratches in Rumney. 
. Arounded, well defined ridge of granite, terminates abruptly 
‘on the south side of the stage road to Plymouth, and is divided 
from top to bottom, longitudinally, by fissures, into regular masses, 
several feet in thickness. On the eastern side is a large vein of 
granite, filled wih se a pei tourmalines in good crystals. ‘The 
jhoresces very beautifully with a pale 
sea-green light. < oe 
Diluvial Rirotche, of uncommon distinctness and dimensions, 
are seen on the west side of this ridge, on an inclined surface, 
near the road, running east and west. 
