[from Proc IoMNH&ASoc vol2 #1 1913]
It is with some hesitation that I send in this report, and much wish some other member of the Society was appointed Secretary to the Geological Section.
Within the last year unusually large quantities of the Bride cliffs have fallen. This has been due chiefly to two causes, First, the action of high tides with inshore wind from the S.E. These have swept away the foot of the cliffs, leaving the lower portion perpendicular, so ready to slide down. In some places the tide has left a depression, with the outer beach raised several feet. But a second cause has been equally, if not more, destructive. The whole face of the cliffs from the top downwards, clay scrablag as well as gravel and sands, have been brought down by water percolating from the surface, along lines of least resistance, till it reached the upper surface of the clays and stiff material, when it flowed out, carrying with it fine sand, so loosening. the gravel and sand above. In some cases the water found its way underneath the clay, and came out in small pipe holes, so undermining these. In other cases, the water lodged behind and gradually forced out the material in front, bringing it down like mud.
Thus, the action of the tide, and percolation of water from above, have tended to the deterioration of the cliffs in conjunction with the weight of the material and strong winds.
Along the shore from the Hydro north, some 150 yards of the best covered sand have been swept away from 6 to 10 feet deep, and, near the Dog Mills, 100 yards of sand and clay have fallen. Beyond the Dog Mlls to Kionlough the brooghs have been carried away two yards or more inside the foundations (rf the stone wall and 180 yards north of the Kionlough rivulet. At the top of the brooghs may be seen a patch of clay deeply stained blue; much of this has fallen, and the same kind of clay is to be seen nearer Shellag. From here on to Cranstal, tons of stiff clay and scrablag lie on the beach. No large boulders were noticed and only a few stones among the fallen debris.
At Ballure, much of the Drift, with large portions of the bank of clay which run along the face of the brooghs have come down. On the S.E. end, where the Drift adjoins the rock, is a mass of dark boulder clay, underneath which and the crushed slate rock are to be seen stone thrust in, as if the remains of a pre-glacial beach, over which the boulder clay has gone up on to the rock above, in a curved direction, as if pressed from the N.W.
In this clay are very many limestone boulders, from 10in. downwards; many round, full of fossils, striated and polished, and of different colours. Leaving out the broken slate and quartz, the small pebbles in the clay are chiefly limestone.
These limestones may have come from the Carboniferous rock of the Solway and Scotland.
On the shore here I have noticed lately two boulders of Carboniferous Conglomerate from Arran, a subangular piece of Dolomite, and a trap rock, rounded, 1ft. 6in. diameter; Buttermere Svenite and Ennerdale, each over 1 ft, diameter.
A pamphlet reprinted from the transactions of the Geological Society of Scotland has been kindly sent by the author, john ,Smith, to this Society, on the ' Carboniferous Limestone Rock of the Isle of Man.' Mr Smith has collected a series of fossils out of these rocks for comparison with those of the South and West of Scotland, to see if any relationship could be established between the two. A long list of such fossils is given. And the conclusion come to is ' The Manx Bedded Limestones appear to be on a pretty low horizon in the Carboniferous formation,' and ' that all the Palaeontological evidence is in favour of the highest Manx Limestone being on a lower horizon than the Limestone of Scotland.'
Mr Smith also mentions finding, at a part of the north-west coast, high up in the cliffs a Loch Garabal granite boulder 5ft. x 3ft. 6 in. in size, and a Mulwharchar granite block from the centre of the Forest of Stair.
The illustrations of the rocks at the south of the Island air very good, and any of our members who wish to become acquainted with the limestone and volcanic rocks of the Castletown district will do well carefully to study Mr. Smith's list.
Mr. A. Bell has lately contributed a paper to our Society in which he sets forth the theory that the accumulations of sand and clay at Sheilag are the remains of a sandbank in sutu formed in a Pleistocene, Sea. A long list of shells found here is given, being correlated to these in the rock boulders, many being Arctic species. The paper brings out many points of interest, though differing, in some ways from what has been already written on this and the adjoining deposits. On the Bride shore some fresh boulders have been seen during the last few years. Several Gneiss, the largest 9ft. x 7ft. x 2ft.; another 8ft. x 4ft. 6in. x 3ft. One darker and harder than the other, 2ft. x 1ft. 6in. x 1ft 4in; one Eskdale Mull, 2ft. 8in x 1ft. 8in. x 1ft. 1in. And two large blocks of green schist, 9ft. x 7ft. x 2in., the other 5ft. x 5ft. On Ballaugh shore the largest blocks of Queensberry yet found were seen, (1) 4.ft. x 4.ft. x 2ft. (2) 2ft. x 2ft. x 1ft. 6in, and (3) 3ft. 4in. 3ft. x 3ft., and several pieces of Arran granite and porphyry.
It may be well to mention here that the peculiar porphyry of Durnrnadoon, Arran, has been sound in the north of Ireland.
If I may I would suggest that members in different parts of the Island collect specimens of boulders found in their districts. These might be kept in somie room and gradually named, and, if possible, assigned to their place of origin. The finder should label them with the name of the place where found. The specimens should be two or three inches square. Small chips are not always easy to identify.
Photographs might be taken of very. large boulders. At one time the Photographic section sent in some very good specimens of rocks and other objects, but it was found that expenses of travelling to some particular place, as well as cost of plates, pressed unduly on some. Perhaps the difficulty could be met by some arrangement, or small payment for photographs sent in and approved of by the Secretary.
The collecting of fossils and shells would be very helpful, and perhaps some of our members would like to examine the bouder clay for Foraminifera; this would take time and require patience.
There is one other suggestion I would like to make, If any members during the summer visit the Lake District, or any part of Scotland or north of Ireland, they might bring back with them, or send through post, specimens of rocks of the District which were well known, e.g., granite, syenue, porphyry, etc., with label attached where found.
| Any comments, errors or omissions gratefully received MNB
HTML Transcription © F.Coakley , 2008