Conglomerates in Gneissic Terranes — A. Winchell. 101 
E. Hitchcock “along nearly the whole western side of the Green 
Mountains in Vermont.”! President Hitchcock states that the 
Vermont conglomerate occurs on both sides of the Green Mount¬ 
ains. He found it “in connection with quartz rock, mica and 
talc schists and gneiss; sometimes merely in juxtaposition, 
sometimes interstratified;” and he gives a diagram showing that 
gneiss is sometimes superposed on the conglomerate. The peb¬ 
bles are generally elongated and flattened, and give other evi¬ 
dence of former plasticity. At Plymouth, on the east face of 
the mountains, conglomeritic phenomena of a similar kind, are 
still more strikingly shown. Here, as in Wallingford, and in 
the Saganaga gneiss, the pebbles do not lie in contact with each 
other. Mineralogically, they are here mostly of quartz, but 
sometimes of granite or gneiss. Dr. Hitchcock found that the 
pebbles were sometimes so elongated and flattened as to reduce 
the conglomerate to a schistic state; and he says: “We doubted 
for a time, whether we could justly include gneiss among the 
rocks that may be originated from conglomerate; for we had 
not found, as yet, decided examples of pebbles in this rock.” 
“We do not despair however, of finding pebbles in gneiss, now 
that we have learned how to look for them.” Dr. Hitchcock 
nrgues that by metamorphic action, many of the pebbles have 
been mineralogically changed without destroying their character 
as pebbles. 
In support of the doctrine of the metamorphism of pebbles, 
Dr. Hitchcock cites a conglomerate found along the eastern 
border of Vermont and southward into Massachusetts. “We 
define this rock,” he says, “as a conglomerate with a cement of 
syenite or granite, or as a syenite or granite with pebbles in 
it, sometimes thickly and sometimes sparsely disseminated.” 
Speaking of an outcrop of this conglomerate on the southwest 
point of Little Aseutney, he says, “on one side it passes without 
any intervening seam into a porphyry, and this into a granite, 
all forming one undivided ledge, so that the conclusion is forced 
upon us that the granite and porphyry have been formed out of 
the conglomerate. Most of the rock on Aseutney takes horn¬ 
blende into its composition, and thus becomes syenite, and this 
abounds in black rounded masses which are for the most part 
t Geology of Vermont , 1861, pp. 29-44. One of the localities is in the 
northeast part of Wallingford. This passage was first published by Dr. 
Hitchcock in Amer. Jour. Sci., IT, xxxi, 372-‘d92, Mar., 1861. 
