354 
changes immediately on the appearance of a new rock on the surface. 
The soil of the Wenlock shale is sometimes more sandy as it approaches 
the Caradoc beds, and on favorable slopes forms good arable land, and 
sustains luxuriant woods ; but where the Caradoc sand-stones reach the 
surface, a wild heath or poor woodland stretches over the country, until 
passing over their edges, we reach the line containing soils of the Llan- 
dillo flags, when fertile arable lands and lofty trees again appear.” 
Bordering the chalk on the north and west in two or three of the 
southern counties of England, is the green-sand formation. The soil of 
the upper green-sand is said to be remarkable for its fertility in the 
United States as well as in England. An extensive farmer in the county 
©f Kent, who had used quantities of bones as manure, found that on some 
parts of his farm they exercised a very beneficial influence on the growth 
©f his crops, while on other parts they produced no visible effect. Being 
unable himself to account for this difference, he sought the aid of geolo¬ 
gy and chemistry, and the mystery was thus explained : The land on 
which a dressing of bones was useless, rested on the green-sand, which 
contains numerous fossils. These fossils were found, on analysis, to 
yield a considerable proportion of phosphate of lime, the chief mineral 
matter supplied by bones. Phosphate of lime, sufficient for the wants 
©f the plants, already existed in the soil; a further application of this 
substance was not therefore required. The Lias clay, a belt of sand 
running east and west through some of the midland counties of England 
is the richest grazing land in Britain. Bones of Ichthyosori and other 
extinct animals are found in the Lias. Cheshire is celebrated for the ex¬ 
cellence of its cheese. Much of the land of that county is kept in perma¬ 
nent pasture, which seldom received any other manure than the droppings 
©f the cows which grazed upon it. Now, milk contains phosphates ; 
©very day’s milking, therefore, robbed the land of a certain quantity of 
its phosphate, and the quantity in the soil had apparently become so far 
exhausted as to retard the growth of the herbage ; for when a dressing 
©f crushed bones was applied to these pastures they had a veiy decided 
and permanent effect, very much increasing their produce. 
A knowledge of what milk contains, what plants require, and what 
the soil affords, had clearly a money value to the Cheshire farmers. If 
they had sooner known that they were gradually exhausting their soil 
