﻿Royal Geological Society of Ireland. 155 



glaciers from their course into other valleys. Allowing the very 

 moderate computation that this impalpable mud accumulates at the 

 rate of only six inches per annum, a deposit of fifty feet in a cen- 

 tury must form. 



If Scotland was at one time covered with an ice cap, or had gla- 

 ciers of any extent (as cannot be doubted), then this deposit must 

 have been equally forming, and as a geological formation must be 

 accounted for. No difference could be detected between this glacial 

 mud and the preLent brick-clays ; and every fact went to show that 

 it was to this that we must look for the formation of these lami- 

 nated fossiliferous clays. The amount of earth deposited on the 

 bottom by icebergs was very insignificant indeed, and could in no 

 degree account for the boulder -clay , though it was shown that much 

 of the boulder-drift in some places could be so accounted for. It was, 

 however, demonstrated that there was a great distinction between 

 the boulders which belonged to the moraine prof onde and those which 

 were carried off on icebergs as part of the ordinary lateral moraines. 



The fjords, as already partially advocated in a paper in the Jour- 

 nal of the Eoyal Geographical Society (vol. xxxix.), he considered 

 due to glacier action, the glaciers having taken possession of these 

 fjords when they were mere valleys, when the coast was higher than 

 now. He further showed that the American explorers are in 

 error when they describe the coast of Greenland as rising to the 

 north of 73°, and subsiding to the south of that parallel. There had 

 been a former rise of the coast, and a fall was now in course of 

 progress through the whole extent. Whether these had previously 

 alternated with other rises and falls is not clearly evidenced by 

 remains ; but no doubt exists that a rise preceded the present sub- 

 sidence. Numerous facts were adduced in support of this assertion. 

 The remainder of Dr. Brown's paper was occupied in an attempt to 

 apply the doctrines regarding the physical action of Arctic ice- 

 action to account for the Scottish glacial remains, and to deduce 

 therefrom evidence regarding the changes Scotland underwent 

 during, and subsequent to, the glacial period. 



EOYAL GEOLOGICAL SOCIETY OF IRELAND. 



A paper was read by Edward Hull, Esq., F.R.S., Director of the 

 Geological Survey of Ireland, " On the Geological Age of the Bally- 

 castle Coal-field, and its relation to the Carboniferous Rocks of the 

 West of Scotland." Read January 11, 1871. 



The object of the paper was to prove that the coal-field of Bally- 

 castle, co. Antrim, was referable to the type of the lower coal-field 

 of Scotland, and consequently of the age of the Lower Carboniferous 

 series — in other words, of the Mountain-limestone. 



The Carboniferous series of Ballycastle, which had been described 

 in 1829 by Sir R. Griffith, F.R.S.*, was shown to consist of three 

 divisions, in descending order: — 



* Report on the Coal-districts of Tyrone and Antrim, to the Royal 

 Dublin Society, 1829. 



