I shall speak first of the Compound Rocks, and secondly of some Simple Minerals, as they occur loose or in situ, mentioning besides in each division under a particular head the primitive rocks, and those that belong either to the class of Transition, or to that of the Flœtz-Rocks.
(a) Primitive Rocks.
Very little of the oldest member of the primitive class of Rocks is to be seen in the Isle of Man in Situ, nor is it the genuine old granite. Some doubts therefore may be entertained whether in the places where it occurs it does not lie in beds, rather than forming the universal foundation of the Isle.
Along the slope of Dun How, on the road from Laxey to Ramsay, and in the middle feeder of a stream that runs into the sea, occurs a small grained granite much decomposed, the quartz bearing but a very small proportion to that of the felspar: when breathed upon, the rock emits a strong argillaceous smell.
The same small granite, but in a sound state, is to be seen at Dun-bridge.
The spot where it comes to the surface may be three or four hundred feet above the level of the sea, but I have made no observation that enables me to determine accurately.
Another small grained granite was found in the working of a lead mine at Foxdale, a place situated nearly in the middle of the island, and 346 feet high.
If the information I received from an old English miner who