No , 200. j 
233 
embracing, to some extent, marine shells, or relics of a very recent date. 
The whole formation is thin, not exceeding, at any place in Essex coun- 
ty, 50 feet, and averaging about 20 or 25 feet. Reckoning from above 
downwards, the strata are, first, a fine white, or yellowish white marine 
sand; second, a yellowish clay; and third, a blue clay. The organic 
relics are distributed mostly through the sands and yellowish clay. — 
The latter eflfervesces strongly with acids, and contains, at some localities, 
immense quantities of argil lo-calcareous concretions, of all shapes and 
forms, and which appear to have been formed by molecular attraction, 
since the deposition of the beds. Another kind of concretion, quite as 
remarkable, is abundant in this formation. It is of a stalactical shape, 
and composed of concentric layers of clay, coloured by the oxide of 
iron, a thing much resembling an organic body, and if I mistake not, 
has been considered as such, but without sufficient evidence. These 
bodies are cylindrical, and are usually vertical in position, with a small 
hole piercing through the centre of each. Sometimes they are solitary, 
and sometimes they form, as it were, groups or clusters. Fig, 15 
Fig. 15. 
is a transverse section of a group of these curious bodies, and about the 
natural size. Sometimes there may be traced from near the surface, a 
straight fibrous root, leading to the centre of each of the cylinders.— 
This appears to have been sometimes the nucleus around which the par- 
ticles began to form. Whether this root, like fibre, is animal or vegeta- 
ble, I have not yet satisfied myself; but I consider the cylindrical bo- 
dies to be inorganic, and to have been formed by molecular attraction 
alone. If these views are correct, it goes to show that changes may 
take place in rocks subsequent to their consolidation, and that internal 
movements may alter materially the internal structure of the rock; and 
one which at first was a mechanical deposit may subsequently become 
highly crystalline. On the New- York side of the lake the tertiary does 
[Assem. No. 200.] 26 
