376, E.. Hitchcock on the Metamorphism of 
admitted ; for the attempt to change their present form would 
result only i in fracture and comminution. ‘The degree of plas- 
ticity, however must have varied considerably ; ‘for some of 
‘them are scarcely flattened or elongated at all—and as has been 
stated, some are not cut off by the joints. 
The neat and clean manner in which the pebbles have been 
an severed by the joints, implies plasticity. 
ugh occasionally we meet with one that has a some- 
what ores surface, as if mechanically broken, such cases are 
rare. Whatever may be our theory of the agency that has 
formed the joints, the conviction is forced upon every observer 
that the materials must have been in a soft state after their 
original consolidation. There is no evidence that the opposite 
walls have slid upon one another at all, as the opposite parts of 
the pebbles coincide. It seems as if a huge saw or cleaver had 
done the work. 
These proofs of Epiastioity. SDP apply essentially, though less forci- 
bly to the micaceo cement which has also been cu 
across by these joints. Tho Galena! small in quantity it 
sometimes forms layers of rade thicknchs interstratified 
with the pebbles. 
me have’ imagined that the elongated, flattened, bent, and 
indented pebbles ‘of this conglomerate may have been worn 
into their present shape and brought into a parallel arrangement 
by the mechanical attrition of waves and currents. We feel 
sure that an extensive and careful examination of the localities, 
and of beaches where shingle is now being formed, will convince 
any one that they cannot have had such an origin. 
do not believe that any beach can be found with peb- 
bles that have anything more than a slight resemblance to those 
at Newport. Those somewhat elongated may indeed be found 
where they are derived from slate rocks. But nowhere does the 
g 
> should have such an extraordinary development on 
ode Island, while it is not marked enough in any other con- 
pis anes in our country save in Vermont, to have arrested the 
attention of geologists. 
e remarkable joints in this conglomerate prove that the 
bbles have been in'a plastic state, and since the strata have 
n much folded, and consequently subjected to strong lateral 
pressure, how could the pebbles have escaped compression and 
modification of form? A mass of ae pag cone omerate when broken 
re on the une of strike, a eal resembles a plug oh 
a era has been rolled ite ote cae and then subj 
_ /strong presire, so that the lumps are distorted and made to con 
form to all the irregularities around them. 
