Jean-François Berger

“ 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. ”

“ When, the thickness of the strata bears a more equal proportion to the length or respective distance of the dip-joints, the natural divisions will come to a cubical form. If on the contrary, the structure be thin-slaty, the rocks will rise spontaneously under the form either of flags or slates. Whatever may be the shape of these natural blocks, their two contiguous sides are constantly coated with the predominating ingredient of the rock itself in its present state. Thus if the rock be quartzose, the coatings of the dip-joints will be veins of pure white quartz ”

“ Between Ramsay and Aire-Point I saw in some heaps of stones a number of pieces and blocks of greywacke, passing from large grained into a small grained texture. The basis is greyish, the imbedded fragments are mostly nodules of white quartz with scraps of a dull and black sort of slate, fusible into a whitish enamel, and abraded plates or broad spangles of mica. The cavities that receive the nodules of quartz when freed from them, appear smooth and even. The pieces of slate turn sometimes clayey, micaceous, and of a brown ferruginous colour. ”

“ All the stratified rocks, but particularly those that have been deposited in a rather horizontal situation, are divided by rents perpendicular to their direction, corresponding therefore with their dip, into solids of dimensions more or less regular, and usually similar in the same individual strata. Thus if the structure of a rock be middle thick-slaty, it will divide itself spontaneously into rectangular solids. ”

“ 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. ”

“ In the Isle of Man this rock, as far as my observation has gone, never contains organic remains. It is farther to be observed that the tract of land occupied by the grey-wacke is less elevated generally speaking, than that appertaining to the clay slate. We can trace the grey-wacke all along the contour of the island, and, except those places where it slopes down gradually, and is outskirted by the flœtz-limestone receding into the sea, it forms a range of bold cliffs ”

“ The increased consumption of coals in the Isle of Man will not so much show an increase of population [21] as an increase of comforts amongst the inhabitants at large, the consequence of a more extensive system of cultivation, and the diminishing number of fishing boats that used to take out in the months of harvest upwards of 2000 of the most active inhabitants of the labouring class. ”

“ I am inclined to think that several of the loose blocks I am going to describe; whenever they occur in any number, are in their birth-places.
On the beach towards Aire-point there are innumerable loose blocks of granite, one of which, rather large in its dimensions, I observed on Aire head at the elevation of 271 feet. They all in their characters differ but little the one from the other. The rock is a small-grained granite, composed of white felspar, quartz and black mica, with a few incidental plates of the latter that are white. ”

“ I met at the village of Craig-neash with a large settled block of mica-slate. The quartz is of a dirty-grey colour. The plates of mica very few and falling into decay.
††† Porphyry.
Very numerous blocks of this rock occur on the beach at Aire-point. The basis is compact felspar of a flesh-red colour, turning yellowish and earthy when going to decay. There is some hornblende disseminated throughout the mass: a few crystals of lamellar and transparent felspar are also imbedded in the basis. The rock acts strongly on the magnet. It emits when breathed upon a sensible argillaceous smell. ”

“ It would seem as if the appearance of the limestone was connected with the absence of the exterior line of mountains on the eastern side of the South Group. We trace it from Cass-ny-Hawin River to Purl-Keill-Moirrey (Langness-point excepted) but it never reaches to any elevation on the slope of the mountains; it is confined to the shore or its vicinity.
It lies conformably over the most superficial of the produced strata of grey-wacke, but the dip becomes less as the strata retreat farther back from the land into the sea. It may be comprehended between 10° and 20°. ”

“ The clay slate formation in the Isle of Man does not appear to belong to the oldest kind of Werner. It is almost limited to the high ground occupying Snei-feldt, Bein-y-phot, South Borroilva, and Cronk-ne-liry-Lhaa. It also occurs at Mount Pellier as hone stone; at Peel-hill and Balla-Gawn, as roofing slate; and as a reddish 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. ”

“ In all the three places the vein appears adherent to the contiguous rock, whether it be greywacke or small grained granite.
At Foxdale a cross metallic vein of lead also was found running a few points from the North and South, that is to say, intersecting the main vein at a great angle; at the junction or counter, the ore grew richer, and many knockings, shods, or balls occurred. The cross course was as fertile as the main vein itself, if the information I received be correct. ”

“ Ann's-head is distinctly stratified, the planes of the strata being quite even, a mode of structure which originates from an accumulation of specks of mica, which render the rock readily fusible into a brown-greyish enamel, while it is infusible in those parts where the mica is wanting.
Along the shore between Kirk-michael and Peel-town, the grey-wacke is rather thick-slaty, traversed by slender and parallel veins of white quartz, coeval with the rock itself since they occur along the seams of stratification. The mean specific gravity of seven specimens of grey-wacke is 2.702. ”

“ As to the great advantage the inhabitants would derive, were coals to be discovered on their isle, I should entertain some doubt, when I consider that the inhabitants of the city of Dublin have their coals put into their cellars at less expence than the persons who live in the County of Cumberland, twelve miles distant from the coal-pits of Whitehaven. ”

“ It occurs both under the form of fine granular and of conglomerate, of a red and grey-white colour, a little to the north of Peel town on the shore, and also on Langness isthmus. In the first place the strata run south-west and north-east, dipping north-west at 39°. At Langness, as we approach towards the south point of the isthmus, the conglomerate strata get higher and more thick-slaty. The materials entering into its composition are of a large size and much loosened. Along the Castle-town River, the sandstone overlies the limestone. ”

“ We pass from the clay slate formation to transition rocks through the most insensible gradations, and in this instance it is to be remarked, that it is the grey-wacke and not the limestone which forms the oldest member of the series. ”

“ On the slope both of South Bor-roilva and Cronk-ne-liry-Lhaa, in the southern part of the group of mountains, occur abundant blocks of rather decayed granite, composed of yellowish and white felspar turning to a state of earth, and disseminated plates of white mica. The texture is loosened to such a degree that large fragments often yield under the pressure of the hand. ”

“ The latter having Snei-feldt almost in the centre, comprehends the highest ground and the mountains of North Bor-roilva, Gob-y-Scioot, little and big Snei-feldt, Bein-y-phot, Kanaghyn and North-Greebah.
A boggy and elevated table-land lies on both sides of the central line of mountains, separating it from the two exterior ones. The summits of the extensive mountains do not all of them greatly surpass the elevation of the intervening table-land itself. ”

“ The rock is highly magnetic, very hard and tough. The mean specific gravity 2.967, the extremes being 3.085 and 2.846. The mass is of a liver-brown colour, with many crystals of an orange or reddish-brown cast imbedded in it. Their fracture is vitreous, but sometimes displays a sort of lamellar texture. The crystallized garnets are much less fusible than the basis or massive garnet: the latter passes into a brownish bead. There are besides in one of the specimens some nodules of radiated zeolite or mesotype. In another the mass of garnet is blended with white felspar. ”

“ Iron pyrites dispersed through the mass is not uncommon, and when scratched the smell of sulphuretted hydrogen is rendered sensible: it burns very white, a circumstance which shows that the colouring matter, being volatile, is of an animal or vegetable origin. ”