. 
: 
By G. Poulett Scrope, Esq., M.P. 109 
coal to the ore, or of ore to the coal, made its extraction once more 
profitable. And now smelting furnaces are, as my readers of course 
know, being built for the purpose at several spot where the ore is 
easily obtainable, and speculation is sanguine as to the results. In the 
neighbourhood of the Westbury station the ore occurs in the upper 
beds of Coral rag. Here, as well as near Trowbridge, there are several 
faults, which bring up the Oxford clay and Cornbrash and Forest 
Marble into contact with the Green sands, as well as the Kimme- 
ridge clay and Coral rag. At Seend again many of these several for- 
mations are brought by disturbances into close contiguity. A fault, 
I must explain to my non-scientific readers, is a disturbance of 
strata which has dropped the beds on one side of a more or less 
vertical crevice or crack, or raised those on the other, so that they 
no longer range together. It is one of the commonest accidents 
of the process of elevation which has raised the marine sedimentary 
beds into high and dry land. The thickness of the entire Creta- 
ceous group is very great; perhaps, from 500 to 1000 feet. 
On many parts of the summit levels of the great chalk platform, 
both in the North and South Downs, are found beds of clay, sand, 
and gravel, called by geologists, ‘Plastic Clay.’ These are outlying 
portions or patches of a great Tertiary marine deposit, of the age 
called ‘ Eocene,’ from its being a period when some few shell-fish 
existed of the same species as those now inhabiting the ocean, (the 
word Eocene being derived from two Greek words, meaning ‘the 
dawn’ of the same,) and there is reason to believe that these beds 
once covered the whole surface of chalk, but were for the most 
part swept off or denuded by the wash of waters which, probably, 
accompanied the forcible elevation of these hills from the bottom of 
the sea. In the lower levels of the New Forest and Hampshire to 
the South, and in Berkshire, Surrey, Middlesex, and Essex to the 
East, these clays, gravels, and sands cover a much larger area than 
in Wiltshire, and they are distinguished by geologists into three 
principal thicknesses. Ist. Plastic clay proper, containing beds of 
 flinty pebbles in sand and clay, sometimes called Thanet sands. 
2nd. Mottled clays with sand beds, called by Mr. Prestwich the 
_ Woolwich and Reading series. 38rd. London clay. 4th. Bagshot 
