DILUVIUM. 
281 
responding cavities are of similar shapes, as in the 
following sketch : 
Near Cape Cod, in Massachusetts, these eleva- 
tions rise to a height of 200 or 300 feet, and are 
very numerous, giving to the country a hilly and 
even mountainous aspect. On digging into them, 
they are found to be composed of a loam, which 
has thus been piled up and scooped out by the ac- 
tion of water. Similar ones formerly existed on 
New- York Island, and over much of the surface 
where the city is now built. Some of these were 
250 feet high, and made up of sand, gravel, and 
bowlders of greenstone, porphyry, serpentine, and 
granite ; most of which evidently came from the 
Palisades across the river. Occasionally, also, 
masses of secondary limestone, containing fossil 
shells, were met with, which must have been brought 
from above the Highlands. Occasionally we meet 
with consolidated alluvium, composed of pebbles 
and, perhaps, masses of different kinds of slate, and 
consolidated together by a cement of iron or lime ; 
which, having been dissolved in water, has thus been 
diffused through the mass. Such conglomerates are 
often called pudding-stone. The reader will now be 
able, perhaps, to form a correct idea of what is un- 
derstood by diluvial ; and he can readily perceive the 
mode of its formation, if he will suppose the agents 
which we have described as destroying rocks to 
A A 2 
