202 DR. THOMAS STERRY HUNT ON THE 
below the ophiolites, and in perfect conformity with the adjacent eocene strata, “ which 
have all their distinctive characters, and present no traces of alteration or of metamor- 
phism,” “the action which produced the phthanites being local, particular, and variable.” 
Recomposed rocks, made up of grains and fragments of serpentine, in a cement generally 
calcareous, are found on the confines of the serpentine and at its contact with the 
phthanite. This is especially seen at Poggio, on the southeast side of the hill, where I 
found a veritable conglomerate of fragments of serpentine imbedded in a paste of silicious 
slate. These facts, as well remarked by Capacci, show that previous to the deposition of 
these eocene beds, the serpentine-mass along the shores of a shallow sea, was subjected to 
a process of disintegration ; “and that, moreover, the formation of the serpentine 
corresponds to a kind of pause in the deposition of the eocene strata.” The ophicalcites, 
in like manner, are found at the limits of the serpentine, and are breccias or conglomerates 
with a caleareous cement. 
§ 102. I have thus given, in great measure in language translated from Capacci's 
memoir, the principal facts observed at Monteferrato, which I have, for the most part, 
verified. They, however, appear to me inconsistant with the hypothesis propounded by the 
modern school of Italian geologists, and with the eocene age of the ophiolitic mass in 
question. The effusion of a great mass of aqueous material from the earth’s interior into 
the eocene sea, its subsequent arrangement and crystallization into mountain-masses of 
euphotide, diorite and serpentine, the elevation of these, and their subsequent disintegra- 
tion to form the ophiolitic sands and conglomerates already described, marks a geological 
period, and a revolution which ought to have left some traces in the surrounding eocene 
deposits. These, however, we are to believe, in accordance with the proposed hypothesis, 
continued after this event to be laid down precisely as before, the alberese and the 
galestro previous and subsequent to the ophiolite making with this one conformable 
series. This process moreover, we are told, was here confined to an area whose greatest 
extent was less than three kilometers, and was repeated at a great number of localities in 
the Italian tertiary basin, in all cases giving rise, not as in ordinary eruptions, to a single 
kind of rock, but to a group of different rocks, indistinguishable in character from those 
which are known to be found in contiguous regions interstratified in crystalline schists of 
eozolc age, 
§ 103. The only explanation which seems to me admissable, and one which is in 
complete harmony with the facts, is that this area of serpentine, with its associated 
euphotides, etc., was an eroded and uncovered mass in the midst of the eocene sea; that 
around its base was deposited the disintegrated material which forms the ophiolitic sands 
and conglomerates, followed by the silicious sediments which make up the phthanite, and 
by the limestones and shales of the middle eocene. The subsequent movements of the 
earth’s crust, which caused the folding of these strata together with the intruding mass of 
eozoic rock upon and around which they were deposited, has resulted in the production 
of an overturned synclinal on the western side of the hill. 
§ 104. AsI have elsewhere insisted, * in cases like the present, where newer strata are 
found in unconformable superposition to older ones, the effect of lateral movements of 
compression involving the two series, is frequently to cause the newer and more yielding 


* Geological Magazine .(Jan., 1882), ix., 39. 

