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veins of lead and copper ores near Laxey, at " Foxdale, and at Breda-head, near Port Erin.
Such is a general view of the distribution of the mineral productions in the island. I shall now give a detailed account of the individual mineralogy, beginning with the mountains.
North Barrule, the northern extremity of the chain, is composed of mica-slate, covered by clay-slate. The new road, from Ramsey to Laxey, is cut in the side of this mountain, and exposes its internal structure, which consists of mica-slate covered by a shining clay-slate, formed of thin laminæ. The clay-slate covers it to the summit in saddle-shaped strata.
Snawfel, the next important one, is composed of the same materials as North Barrule. The clay-slate, which is more glossy, and of a more micaceous appearance, covers the mica-slate in mantle-shaped strata, leaving the latter projecting through them to form the summit. The mica-slate contains much quartz, which is often crystalised in transparent pyramidal crystals. The clay-slate on this mountain becomes less shining as we descend, that is, as we recede from the mica-slate, and gradually gives way to grey wacké-slate. This appearance is a very
general one in primitive countries ; the oldest strata of clay-slate gradually approximating the more crystaline appearance of the primitive rock on which they rest, as they approach it. The sides of Snawfel are generally covered, to the depth of several feet, with turbary, the surface of which is green with mosses and rushes. The verdure continues to the top, and is frequently studded with the snowy tufts of Eriophorum vaginatum and E. polystachion, (cotton grass.) Here and there the strata of the mountain are exposed to view.
Penny-pot (perhaps Pen-y-pont*) is com posed of clay-slate to the summit, resting in all probability upon mica-slate. The clay-slate resembles exactly that of North Barrule in colour, lustre, and the thinness of its laminæ." This is the most marshy of the mountains ; and the ascent, even in dry summer weather, is consequently tedious and unpleasant. · Mount Kreevey is very rugged and precipitous near the road from Douglas to Peel. The strata nearest the surface are glossy elay-slate, traversed by many large veins of quartz, which are
* i. e. head or hill of the bridge.
often two or three feet thick, and generally contain a considerable quantity of mica. Micaslate lies immediately under the clay-slate..:
South Barrule, the southern extremity of the ridge, presents on its north side many blocks of granite, composed of silvery mica, reddish white feldspar, and grey quartz. These are too numerous and too huge ever to have been transported by human art. Fragments of mica-slate make their appearance on several parts of the mountain, but the prevailing rock is a clayslate similar to that of Pen-y-pont. From these facts it is highly probable that the nucleus of this mountain consists of granite.
This arrangement may also be considered as that of the great mass of the island, except that, in the plains, the common clay-slate gives place to grey wacké-slate. .
In tracing the strata from Douglas towards Castletown we find that the grey wacké-slate continues from the high land to the sea shore, without interruption, as far as the first creek, northward of Derby-haven. In approaching the shore from the mountains, the clay-slate becomes less and less shining, exhibiting more the appearance of a mechanical deposit, till it
passes into grey wacké-slate. Here its fresh fracture is dull; and the strata, which, near Douglas, are highly inclined, dip only 10° or 15°. At this place we find a bluish grey limestope, containing impressions of spells and other marine exuviæ. It lies over the grey wacké-slate. The line of stratification is distinct, and in some places filled up with a thin layer of white clay, which seems very pure. The clay does not in the slightest degree effervesce with açids. The limestone contains
veins of calcareous spar; and, along the coast, . it is much corroded on its surfacę by the action
of the weather. The strata are generally from one to four feet thick, dipping 10° or 150 towards the south west.
A considerable portion of the lime-stone tract exbibits alternations of lime-stone with grey wacké-slate, the strata of which are but a few inches in thickness. This circumstance demonstrates the lime-stone to belong to the class of rocks denominated by Werner “rocks of transition.” This lime-stone, in colour and in the organic remains which it contains, very much resembles the lime-stone of transition found on the mountains near Crook-Inn, on the Moffat
road in Scotland. The clay found in the in. " sterstices of some of the strata of lime-stone most probably arises from the decomposition of the grey wacké-slate by the constant action of the weather. Indeed this slate, where exposed to the air, is, for the most part, friable and crumb
With the small interruption of the isthmus - and promontory of Langness, the lime-stone con.
tinues along the winding shore to the further part of Pool-vash bay. Here it is highly indúrated, and rests upon a glossy clay-slate intersected by veins of quartz. A little to the south it becomes still more indurated, and is quarried, below high water mark, as a pretty good marble for tomb-stones, the formation of which is facilitated by the increased thinness of the laminæ. The steps to St. Paul's church in London are from these quarries, and were presented by Bishop Wilson.
A short sandy isthmus joins the promontory of Langness to the main land. The promontory and the islet of St. Michael are composed of grey wacké-slate, excepting a small tract, a few yards wide and some hundred yards long, on