522 ReporU and Proceedings — British Association — 



Besume. — (1) The pale felspathic grits and black slates of New- 

 port Bay and Cardigan are of Middle Bala, or Caradoc age (not 

 Llandovery, as hitherto supposed). Above these come (2) rolling 

 beds of pale-coloured, coarse, flaggy slates, and pale blue splintery 

 slates, doubtless also of Bala age. Some rather darker shaly slates 

 (3) with rably shales, and "cone in cone " concretions, next succeed ; 

 and then we meet with (4), a small compact set of pale felspathic 

 grits of the same character as those at Cardigan. These also T 

 regard as probably of Bala age (Upper Bala Slate Series). The 

 OA'erlying rather dark shaly slates (6) with some rab, presenting tlie 

 gradual incoming of the Aberystwyth Grits, are I believe passage 

 beds of Caradoc-Llandovery age. 



The G-rits of Llangrannog are clearly the same as those of Aberyst- 

 wyth (Aberystwyth Grits), and the overlying slates with worm-like 

 markings are our " Metalliferous Slates," which belong to the same 

 great rock group. 



There is no evidence of any stratigraphical break in the rock 

 groups of South Cardiganshire, from the Llandeilo to the Llandovery 

 periods inclusive ; but the whole series appears perfectly continuous. 

 The Aberystwyth Grits are less developed than further north, this 

 being near the line of their southerly disappearance by dying out. 

 As in North Wales (Dovery Valley), we find here a considerable 

 series of Upper Bala Slates passing up into the Llandovery group. 

 I have proved elsewhere^ that our Cardiganshire rock series occupies 

 a position conformable beneath the Tarannon Shale, and here we 

 have the evidence that it is superior to and conformable with the 

 Bala formations. No exact upper boundary line for this group can 

 be determined, for it passes up insensibly into the Tarannon Shale, 

 and again in its lower horizons we find its limits ill defi.ned, 

 gradually passing down into a great series of imperfect slate rocks, 

 the main mass of which belongs to the Upper Bala Group. We find 

 no great physical break, but perfect continuity amongst the Silurian 

 and Cambrian rocks of South Wales. 



IL — On the Origin of the Haematite Deposits in the Car- 

 boniferous Limestone.^ By Edward Wethered, F.G.S., etc. 



UCH has been written on the origin of iron ore deposits by 

 Doctors Sterry Hunt^ and Bischof,* both of whom insist on the 

 active part which decaying vegetation has taken in the process. 

 According to the former authority,^ " we find in rock formations of 

 very different ages, beds of sediment which have been deprived of 

 iron by organic agencies, and near will generally be found the ac- 

 cumulated iron." ..." I now wish," he says, " to insist upon the 

 property which dead and decaying organic matter possesses of re- 

 ducing to protoxide, and rendering soluble, the insoluble peroxide of 



1 See Quart. Journ. Geol. Soc. 1881, p. 141. 



2 Eead before Section C. August, 1882. 

 2 Chemical and Geological Essays. 



* Chemical and Pliysical Geology. 



* Chemical and Geological Essays, p. 228. 



