SANDSTONES. 
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limestones, partly because they are not so readily worked, and 
partly because good sandstones are not common in the south- 
east of England. The sandstones of the Tertiary and upper 
Secondary formations, are in fact generally too soft. The 
“ grey wether sandstone,” however, is a material of exceptional 
durability, as attested by Stonehenge and other megalithic 
monuments in which it has been used ; yet this is merely an 
altered sandstone from certain Eocene deposits which were once 
spread over the chalk downs. 
The “ hearth-stone ” and “ fire-stone,” of Surrey, are soft cal- 
careous sandstones from the Upper Greensand, at the foot of the 
chalk escarpment. At Godstone the stone is worked in sub- 
terranean galleries, which are really mines. The Lower Green- 
sand yields in many localities brown sandstones and grits, called 
“ carstone,” employed locally for building. Several sandstones 
from tbe Trias are exhibited; whilst many of these are red 
stones, others are white and even greenish, as shown by the 
Quarella stone, quarried near Bridgend, in Glamorganshire. 
The red and white Mansfield stones are dolomitic sandstones,, 
associated with the magnesian limestone of the Permian: 
series. 
The Carboniferous system is rich in excellent sandstones,, 
especially in Yorkshire, Lancashire, and Derbyshire, where they 
are worked both in the coal-measures, and in the underlying- 
millstone -grit ; examples are exhibited from Bramley Fall, near 
Leeds ; from Darley Dale, in Derbyshire, and many other well- 
known localities. 
A Grit is a rather coarse sandstone, containing sharp angular 
grains. The Millstone Grit is in some parts a conglomerate,, 
with rather large pebbles of quartz ; whilst in other cases it 
becomes felspathic, and has evidently been derived from the 
disintegration of granite ; such a rock is sometimes termed 
arkose. 
In the Midland Valley of Scotland, the Lower Carboniferous 
series includes many valuable sandstones, such as those of 
Craigleith, so largely employed in Edinburgh. These sand- 
stones occur in the upper part of the Calciferous Sandstone 
series known as the f ‘ Cement stone group.” The term “ liver- 
rock,” is applied to the thick-bedded sandstones, which can be 
quarried in large blocks. 
The collection of sandstones includes, in addition to the 
specimens already referred to, several cubes from the Old Red 
Sandstone, a formation which yields, especially in certain parts, 
of Scotland, much useful stone not only for building but for 
paving purposes. 
Flagstones and Tilestones. — Wall Gases IX. and X. 
Two small Cases have recently been erected against the wall 
opposite to the general collection of building-stones, for the display 
