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TERTIARY SYSTEM. 
VIII. TERTIARY SYSTEM. 
§ 1. Tertiary and post-tertiary clays ; Albany and lake champlain clays. 
This formation is the most recent in New-York, if we except the peat and marl beds,, 
which have usually been referred to the present era. It apparently consists of three por¬ 
tions : the lowest, a blue stiff clay ; the middle, a lighter colored clay ; and the uppermost, 
a sand. The middle portion differs but little from the lower in composition. The diffe¬ 
rence in color is partly owing to a longer exposure to the atmosphere, by which it becomes 
lighter, and even a pale brown or drab. The sand appears between the layers, but only 
in extremely thin beds : the great mass of sand is on the top of the formation; it is a ma¬ 
rine deposit, a point which was determined at an early period of the New-York survey, 
by the discovery of fossils, known as living inhabitants of the Atlantic ocean. 
The largest or most extensive deposit occupies the Champlain and the St. Lawrence basins, 
from which it extends into the Hudson valley. It is impossible to determine its real extent; 
for it differs in no respect from other clays, and can not be distinguished from them,, unless 
it is traced continuously to beds which are well known, or to those which contain fossils. 
It is one hundred feet thick upon Lake Champlain; and what is worthy of special notice, 
is that the deposit rests on the grooved surfaces of the Champlain rocks, or else upon beds 
of drift. It exhibits all the characters of a deposit made during a period of perfect quietude. 
We have to notice, however, that at the close of this period, one of some violence suc¬ 
ceeded ; this is clearly indicated by the removal of large portions of the formation. The 
sand, and part of the clay, has apparently been removed to distant points, leaving only the 
lower portion, and even sometimes the whole mass down to the rock has been removed, 
§ 2. Fossils of the tertiary system. 
About twenty-two or twenty-five species of marine animals have been discovered 
towards the upper part of the clay. The indurated clay, or claystones, in one or two 
instances, have contained fossil fish. Besides these, a fossil jaw of a walrus was found by 
Mr. Lyell in this formation in Maine. 
Of the conchifera belonging to this deposit, the Saxicava rugosa, and the Sanguinolaria y 
have a wide distribution ; the remaining species are quite limited, and are confined to one 
or two places on the borders of Lake Champlain and of the River St. Lawrence. At 
Beauport, a village four miles from the city of Quebec, about fifteen species of fossils have 
been found, all of them distributed throughout a single bank of clay and sand. Some of the 
same species inhabit the northern seas ; and hence Mr. Lyell maintains, that during the era 
of this deposit, the temperature of the part of the continent where these fossils are now found 
was lower than it is at present. Doubts are thrown over the justness of this conclusion, 
by the fact that some of the species are the present inhabitants of the Atlantic ocean on 
the coast of Maine ; that marine animals have a wide distribution ; and as our waters have 
