
RECENTLY DISCOVERED IN CRAIGLEITH QUARRY. 217 
17; and when they vary, their proportion remains nearly the same to one 
another, or as 3°5 to 1 nearly. 
The composition of the larger of the two Granton fossils is precisely the 
same as that now stated. No chemist indeed, while analysing it, could know, 
unless told, that he was not examining an araucarious fossil from Craigleith 
quarry. The charcoal amounts to 3 per cent., and the three carbonates occur, 
each of them in large proportion. In one analysis I got 31:8 of carbonate of 
protoxide of iron. 
THE SANDSTONE Bep oF THE Fossits.—The sandstone of Craigleith quarry 
has been long celebrated for its whiteness, hardness, and durability. Until 
about thirty years ago scarcely any other stone was used in building the houses 
of the New Town of Edinburgh; but the railways have substituted a softer 
quality of stone, which, though inferior, is preferred by builders, because much 
more easily worked. The quarry is within a mile of the great trap outburst of 
Corstorphine Hill, to which it appears to owe the inclination of its beds east- 
wardly. The excavation of the quarry is now about 200 yards long, 150 yards 
wide, and at the deepest workings 185 feet deep from the sandstone surface. 
In most places nothing overlies the sandstone except some feet of gravelly 
sand, with also a few thin layers of intermingled sandstone and shale. The 
west cliff of the quarry is as it were split by a great wedge of coarse shale, 
entering from the north, between the sandstone beds, to a length of about 80 
feet, with the point of the wedge directed and inclined southward. But the 
whole visible rock elsewhere is an unbroken cliff of sandstone. The sandstone is, 
for the most part, of a uniform very pale greyish-white colour. It has a finely 
granular dull surface, breaks with difficulty, and preserves its edges almost 
indefinitely under ordinary care. It resists the entrance of water into its tex- 
ture with obstinacy, and retains its colour with little change under atmospheric 
exposure, except in the smoky air of a town. Its density is 2°45. When quite 
dry, by being kept some days in a warm room, its powder does not lose weight 
at all on being subjected to the action of diluted nitric acid ; neither is there the 
slightest effervescence. Hence there is no earthy or iron carbonate or alumina 
to bind the particles together which compose the rock. It is a pure siliceous 
sandstone, formed by accretion of sand, not by agglutination. These are the 
characters of what the workmen call their “liver-rock,” by which they mean 
the finest stone for building purposes. 
But to a distance, occasionally of several feet, around the araucarious fossils, 
_ the rock has undergone a remarkable change, both in external characters and 
in chemical composition. It is tougher than the “liver-rock,” scratches with 
the knife, though not easily, presents on the surface of a fresh fracture a decided 
