160 Association of American G'eologists and Naturalists. 
east. In the third division, still greater difference is perceptible in New 
York than west or south. 
The sea here emphatically teemed with life, while at the west it was 
cold, dark and deep, with scarcely an inhabitant. And we may also 
learn that the same rocks may at one point be highly fossiliferous, and 
at another destitute of them, and may thus often be mistaken for differ- 
ent rocks, if sole reliance is placed upon fossil character. The next 
rock exhibits even greater changes in the organic contents and compar- 
ative conditions of the eastern and western extremes of this ocean. 
These consisting of sandstones and shales, red, green and gray, with a 
few shells, fish scales and fragments of bones, are equivalent to the Old 
Red Sandstone of Europe. In the eastern part of New York, it forms 
the Catskill mountains, and in Pennsylvania, it is about two thousand 
feet thick, but it can scarcely be identified beyond the Genesee River, 
nor do we know that it reappears at the west. Then follows a 
coarse conglomerate, which, after the disappearance of the Old Red, 
rests upon the Chemung group. In Indiana, however, the rocks of the 
Chemung are succeeded by a fine sandstone, which contains beds of 
oolitic limestone, with fossils entirely different from any at the east. 
Succeeding this limestone we have the conglomerate, which at the east 
rests upon the Chemung group. 
Thus we have the great coal formation resting in one place upon the 
Chemung group, at another upon the Old Red Sandstone, and at anoth- 
er upon the limestone, which underlies the coal basin of the west. He 
concluded by remarking, that from what has been said it was evident 
that this immense ocean was bounded on the east by a continent which 
supplied all the mechanical deposits; that during some periods there 
was a cessation of these deposits, and calcareous deposits were produ- 
ced. The influence of these deposits did not extend throughout the 
whole area, and beyond their reach flourished corals and many other 
beautiful forms in security, which thus prevented them from odour 
beyond their own domains. 
[Mr. Hall’s paper was read partly in the morning and partly 
in the afternoon, but it has been given above without division. | 
Dr. Houghton, referring to the paper just read by Mr. Hall, 
said that the sandstone of Lake Superior, lying east from Ke- 
wuna Bay, dips at a moderate angle to the south, or a little east of 
south, and passes under a limerock which he considers to be the 
equivalent of the Trenton limerock of New York; while those 
conglomerates and sandrocks lying westerly from Kewuna Point, 
and flanking the trap on the north, dip to the north, mostly at a 
high angle. ‘These last mentioned rocks are probably contem- 
