104 UPPER SECONDARY ROCKS. 
Above the lias clay we have what is called the 
Cheltenham or inferior oolite, which in some places 
is an arenaceous deposite, sometimes consisting of 
nearly equal divisions of soft oolite and slightly cal- 
careous sand, with occasional oolitic iron ore : over 
this, in some places, is a pecuhar kind of clay, called 
Fuller^ s earth, valuable in the useful arts ; occasion- 
ally it forms beds 150 feet in thickness. Above 
this comes a slaty calcareous limestone, called Stones- 
field slate, remarkable for its organic remains ; and 
next in order is the great oolite, which contains the 
best and largest beds of building stone, called Free^ 
stone. Many of the handsomest houses in Bath 
(England) are built of this stone. As we ascend 
we next meet with what is called Forest marble, 
containing argillaceous deposites, termed Bradford 
clay. Next we find a coarse, shelly limestone, 
called C ornhr ash, * fwW oi fossil remains. The above 
deposites form what may be called the second divis- 
ion of the oolitic series in the ascending order. 
The third division embraces the Oxford clay, the co- 
ral rag, calcareous sandstone diXid. freestone, and Kim- 
meridge clay. The upper and last division of oolite 
consists of Portland sand and Portland stone. The 
latter is of a yellowish white colour, and forms a 
very fine building stone. The average thickness 
of the deposites in each of the above divisions is 
600 feet, making 1500 feet for the whole ; none of 
which are known to exist in the United States. A 
great variety of fossil remains are found in the se- 
ries, especially in the Stonesfield slate, such as 
those of the megalosaurus or gigantic lizard, which 
was forty feet in length and twelve feet high ; also 
of birds, and animals of the opossum genus, and of 
* This word derives its name from the facility with which 
it disintegrates and yields to the plough ; being, according to a 
provincial term, hrashy or breaky enough to enable the plough 
to prepare the surface where it prevails for wheat, which is al- 
ways called corn in England. 
