558 Notices of Memoirs — Geology of the Isle of Man. 



isTOTiGES OIF nvcEivnoii^s. 



Abstracts of Papers read before the British Association at 

 Oxford, August 9-14, 1894. 



I. — The Carboniferous Limestone, Triassic Sandstone, and 

 Salt-bearing Marls of the North of the Isle of Man. By 

 Professor Botd-Dawkins, F.E.S. 



THE Ordovician slates, quartzites, and conglomerates, and the 

 associated volcanic rocks of the "massif" of the island gradually 

 pass underneath the sand, shingle, and clay of the Boulder-clay 

 series in going northward along the coast towards Kirk Michael, 

 until they disappear altogether from the cliffs and the shore. They 

 stand up conspicuously along the ancient shore-line extending from 

 Kirk Michael to Ballaugh, Sulby, and Eamsey, commanding the 

 low, sandy, and marshy region which forms the northern portion 

 of the island, contrasting in its flatness with the lofty rolling 

 Ordovician hills behind, culminating in Startfell, Snaefell, and 

 North Barule. This contrast is obviously the result of a difference 

 in the physical character of the rocks in the two districts. The 

 problem as to which rocks underlie the glacial strata in the former, 

 ■which had occupied the author's mind for many years, is now 

 partially solved by the three borings which have been made under 

 his advice by Messrs. Craine in 1891-94 in search of the Coal- 

 measures of the Whitehaven field, at the Point of Ayre, at Blue 

 Point, and at Shen Moar. The boring at Shen Moar revealed the 

 existence of the Carboniferous Limestone at a depth of 167 feet 

 6 inches below the drift. The next bore-hole, at Blue Point, about 

 40,050 feet to the north-east of that at Shen Moar, revealed the 

 presence of moi-e than 60 feet of Red Sandstone buried 171 feet 

 beneath the drift. The Eed Sandstone in this section is, in his 

 opinion, identical with the St. Bees sandstone, or lowest member of 

 the Triassic formation in the district of the Lakes. This is greatly 

 strengthened by the discovery in the third boring at the Point of 

 Ayre, to the east of the lighthouse, of the Triassic marls with salt, 

 at a distance of a little under five miles from Blue Point. The 

 diamond drill was used from a depth of 452 feet to the bottom. 

 The total thickness of the salt-beds amounts to 33 feet 6 inches, 

 and the bore-hole happened also to intersect a brine run 2 feet 

 6 inches in depth. If this section be compared with that published 

 by Mr. Dickenson of the saliferous marls of Duncrue, near Carrick- 

 fergus, it will be found to be practically identical. The same 

 series of salt-bearing marls is also worked at Barrow-in-Furness 

 and at Preesal, near Fleetwood. The salt-beds in each of these 

 cases are variable in thickness, and those in the Isle of Man are 

 thinner than in the other localities. It must, however, be re- 

 membered that the Manx boring has not been put down to a 

 sufficient depth to test the true thickness of the salt-field. The 

 discovery is of great theoretical importance, because it links on 

 the deposit at Barrow with that of Carrickfergus, and shows the 



