* 
of the United States. 35 
sand, pebbles and lignite render it easy to distinguish it. At 
the same time it may be considered as the most important 
of the tertiary formations, on account of its use in the arts. 
was first discovered in France, but is»peculiarly prom- 
inent, and finely illustrated in England, at Alum bay in the 
Isle of Wight, where from some unknown cause, the stra- 
ta have assumed a vertical position, and the sea washing 
the face of the cliffs has presented a fine section to the 
ist. 
08 
In England the plastic clay is, I believe, found only in 
this formations but in France, a bed of white clay and sand 
accompanies some of the higher formations. Jt must re- 
main for future observations to ascertain whether some of 
the white oe — of America belong to the higher or 
lower: forma I am inclined to think that most of the 
eas are contemporaneous with the English 
plete dey. and lower French strata, but i it isa point which 
must be decided at rand 
a future time, whe 
position of these formations is known in America. 
This formation is the most extensive of the tertiary strata 
in the United States, and presents an important feature in 
its Geology ; it may be traced at different points nearly to 
the distance of a thousand miles. The following are some 
of the localities where it occurs. 
he situation where it ‘may be studied with the greatest 
advantage and where it is exhibited in greater perfection 
than in any other part of the United States, isat Gay Head, on 
the island sometimes called Martha’s Vineyard in Mass, 
The cliffs are two hundred feet in height, and consist of a 
succession of beds of clay, sand, ochres and lignite of the 
brightest hues, and the waves of the ocean which flow at 
the foot of the hill are tinged by the coloring ower of the 
sands and clays. Iam informed by a gentleman of Phila- 
delphia, who has visited this place, that sani has been 
found floating in the ocean, near, undoubtedly derived from 
the lignite - — formation, and I have a specimen of it in 
my collect 
At Sand’s | Point upon Long-Island, it is very conspicu- 
ous, consisting of beds of very white clay and fossil wood. 
The range of hills which extend through the centre of this 
island, are composed of diluvial sand, gravel, &c. accom- 
panied by enormous masses of rolled pebbles and bowlders. 
