ASHBUIINIIAM STRATA. 
2^20 
Blit the strata under consideration have suffered 
such extensive displacement ; and, even ^¥here ac- 
cessible to observation, present so many obstacles 
to an accurate knowledge of their position and 
relations, that we can only attempt an outline of 
their general characters, for future observers to 
till up and correct. 
They may be defined as a series of shelly lime- 
stone and shale, alternating with blue clay, and 
containing subordinate beds of grit, ironstone, 
limestone, and sandstone. 
Limestone, of a dark, bluish-grey colour, con- 
taining immense quantities of bivalve shells, which 
are more or less changed into a spathose calcare- 
ous spar, and whose characters and forms are but 
occasionally preserved, is the most characteristic 
deposit of this group. In texture, appearance, 
and fracture, it bears considerable resemblance to 
the Sussex marble, but is readily distinguished by 
the semilunar markings which the sections of the 
bivalves present. The shale, by which it is ac- 
companied, is also of a dark blue colour, very stiff, 
sometimes slaty, and laminated ; and abounds in 
the same kinds of shells as the limestone, in a 
white friable state. 
At Archer’s Wood, near Battel, on the estate of 
the Earl of Ashburnham, extensive limeworks 
have been carried on for the last century ; shafts 
are sunk through the shale and clay, to the dejith 
of 100 or 1^20 feet, to the limestone, which lies 
beneath, and is dug up and converted into lime ; 
the thinner slabs are used for ])aving. These 
strata occur in the following order : — 
