232 
GEOLOGY OF THE FOURTH DISTRICT. 
The specimen is from the shore of Lake Erie, where hundreds are annually thrown down 
upon the beach by the undermining action of the waves. The usual form of these bodies 
where this one was obtained, is that of a flattened spheroid. Great numbers of these are 
burned for hydraulic cement between Dunkirk and Portland harbor, and they produce a very 
good material for this purpose. At the locality alluded to, they are frequently two or three 
feet in diameter, and not more than half a foot thick. There are several of these in the State 
Collection, showing the varying forms and different sizes. 
In the black shale near Sturgeon point, I saw one of these concretions, almost spherical in 
form and six feet in diameter. 
On the Genesee river these concretions are often of the size and form of common loaves of 
bread, and many of them present the structure of “ cone in cone.” This structure occupies 
from one to two inches on the outer surface of the concretions. The same structure is also 
found in some wedge-form layers in the same situation, both on the Genesee river and on 
Lake Erie shore, and it is well known along nearly the whole distance from Chautauque 
county, New-York, to Cleveland, Ohio. I have not had an opportunity of ascertaining whether 
it holds precisely the same position throughout, but in the western part of the State, its posi¬ 
tion is the same for more than one hundred miles in extent. Many beautiful specimens have 
been obtained from Erie, Pensylvania, and other places in that neighborhood. 
too. 
1 . 2 . 
Cone in Cone. 
The woodcut illustrates the usual appearance of this curious structure. The mass is of a 
peculiar kind of clay, and the cones are often composed of concretive laminae, presenting a 
transversely striated or wrinkled surface; they are also striated longitudinally. 
Fig. 1, represents the common structure of the mass. Fig. 2, is a single cone detached 
from the others. 
Casts of flowing mud. 
The phenomena presented in these bear some analogy to a concretionary structure, but from 
numerous examples it seems to be demonstrated otherwise. The appearances are similar to 
those presented by a semifluid mud, or any viscid body flowing over a slightly descending 
surface, or impelled along by some other force. A very analogous appearance is often pre- 
