220 Connecticut River Valley. 
solid strata. In excavating a well in East Windsor, animal* bones 
were found twelve feet below the surface of the rock, perfect in color, 
form and substance. It is evident that before the red rock basin was 
formed, the crust of primitive rock had been broken up, and variously 
changed to pebbles, gravel, sand, clay, and all the variety of mineral 
substances and forms found reunited in the secondary. Fishes also 
lived in the waters, and trees, plants, and animals on land. 
Layers.—The secondary rock is formed in layers, one over anoth- 
er, differing in thickness from a few inches to several feet. The di- 
vision into layers may have been caused by occasional deficiencies of 
the cement; or, more generally, by the uncohering nature of the 
substances which were deposited and came in contact, at the surfaces 
of separation. . 
Plates.—In many places the layers are manifestly composed of 
successive thin plates, which often separate with the application of 
moderate force. The place of separation is distinguished by differ- 
ence of color and materials, or by change from coarser to finer. 
The distinction of thin plates in the secondary strata is as manifest, 
and frequently of the same kind, asin the clay beds before described. 
A sandstone layer, a foot thick, will often split into twenty or thirty 
plates, each similar to the others, in materials and arrangement, in- 
dicating that a uniform law controlled the formation of the whole. 
Distribution of the ingredients.—The larger fragments and peb- 
bles are chiefly found around the borders of the secondary formation. 
They have been traced and are abundant on the eastern margin of 
the secondary strata, in every town from Northfield to Chatham. 
In the more central parts of the red rock basin, the rocky strata are 
generally composed of very fine materials. In recent excavations of 
not less than fifteen thousand cubic yards of rock, at Enfield falls, 
at numerous positions along an extent of several miles, the materials 
of the rock were so uniformly fine, that a fragment or pebble as large 
as an acorn, is not known to have been met with. Such is also the 
general fact in the excavation of wells at Hartford, Suffield, and oth- 
er towns situated centrally in the secondary, and in the bed of the 
river at Hadley falls. Some cause of extensive influence must have 
occasioned the existing distribution of coarse materials around the 
borders, and fine in the central portion of the secondary formation. 
* A vertebral animal. 
