Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/113

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diminishes in degree as the distance from the dyke increases, and it is about 20 feet before the limestone acquires its perfect properties of burning into good lime. The same thing is observed in both the strata of limestone. The stratum of what I shall term a species of tuf, composed of felspar and carbonate of lime, is indurated as it approaches near to the whin, and it then resembles in structure and colour the whin itself; it is much fuller of joints near the dyke, than at a distance from it. In no case did there appear to be a complete junction of the whin with the limestone, or with the tuf; but there is invariably a small fissure, that seems to separate them to a great depth, on the edges of which the limestone sometimes assumes a sparry structure, and is in some places considerably mixed with pyrites. In one part of the dyke a piece of the tuf is enveloped in the middle of the whin; this fragment is about 60 feet in length, and 2 feet in breadth at its broadest part, and the two ends terminate in points.

The following is a section of the strata, obtained from the information of the proprietor of the lime works.

FEET
Limestone 22
Tuf 39
Black metal, argillaceous slate 27
Limestone 16
Slaty and micaceous sandstone and black metal Coal, a thin seam. 27

That part of the strata, which the workmen called argillaceous, I had not an opportunity of examining, at least where it was in contact with the whin, it being under water. Neither could the coal be seen, as it is at too great a depth.

The strata dip about one yard in six to the south; but their general inclination in this district is to the east and north-east.