Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/48

From Wikisource
Jump to navigation Jump to search
This page has been validated.
Dr. Berger on the Isle of Man.

half-decomposed slate along the mountainous road that runs from Ramsay to Douglass, between Slieau-Lhearn and little Snei-feldt.

The clay-slate of Snei-feldt has a close texture. Its basis is remarkably fine, the gloss not very resplendent: it fuses into a brownish enamel, and is traversed by slender veins of granular and whitish quartz.

The clay slate of Bein-y-phot has a dull black-brown colour, while that of Cronk-ne-liry-Lhaa is sometimes so glossy as to resemble plumbago, is soapy to the feel, fusible into a yellowish and bubbly enamel, the fracture is foliated, with some minute specks of white mica.

On the slope of South Bor-roilva the clay slate assumes a more flinty character, the grain is also very close. At Peel-hill, in a situation still lower than on the slope of South Bor-roilva, we come to another flinty clay slate, in the basis of which are distributed extremely minute specks of mica; it fuses into an olive brown enamel. The rock is quarried, but the beds that are used for roofing alternate with two others of a different nature. The one is a greyish compact felspar, the structure of which is rather thick slaty, with a close texture, the fracture is short scaly, it contains dispersed specks of mica, and fuses into a white frothy enamel. The strata run nearly East and West, dipping at an angle from 75° to 90°. The other bed alternating with the roof slate is called the Knobby Side, and forms the wall of the quarry itself. It has a silky lustre, and the planes of the strata, which are nearly vertical, instead of being even, offer little cavities smoothened and adapted for the reception of prominent parts similar in dimensions that exist on the contiguous bed. There is another roof slate at Balla-Gawn of a dark grey colour, rising by flags and of a fissile texture.

The clay slate of Mount Pellier has a structure rather thin slaty,