﻿434 



DR. C. A. MATLEY ON THE 



[Aug. 1908, 



SXB.XX.H.PHXCA. '^--— 

 ^^^^'- IN FEET. 



PaX^OKTOLOGICAL i COBBELATED BeDS 



Zones. ^ ^"^ ^?^ 



Rush Aeea. 



Loughsliinnj' Black Shales 

 (top not exposed). 



JPosidonomya • Limestone 

 Group. 



Cyathaxonia-'BediS, (base 

 not seen). 



(Gap) 



Dihunopliyllum - Lime - 

 stones. 



(Gap) 



Holmpatrick Limestone ... 

 Lane Conglomerate 



110 ^ 



200 -• 



(Gap) 



100 

 (Gap) 



180 ^ 



1 

 200 i> 



Upper Posidonomya-Zone 



Lower Posidonomya-Zorxe 



(Pi). 

 Cyathaxonia-Snhzone 

 (locally divisible into 



(Rush ^ ^^ > (Loughshinny 

 paper) | j^^^ ^ paper) 



but overlapping). 



Upper jDibunophylhim-Zone 

 (D,). 



? D (of unknown position). 



Not represented. 



Not represented. 



Cyathaxonia -Beds of 

 the Bathing-Place 

 (north of Rush) and 

 Giant's Hill. 



Curkeen-Hill Lime- 

 stone. 



? Carlyan Limestone. 



? Rush Conglomerate- 

 Group. 



? Rush Slates (top 

 part only). 





60 J 





Total thickness of deposits ~^ 



exposed in the Lough- [> 1110 

 shinny coast-section ...J 







IV. Conditions or Deposition in the E,ush-Lotjghshinny 

 Area. [C. A. M.] 



From the description given in this and in our former paper of 

 the lithological character of the Carboniferous deposits laid down 

 in the E-ush and Loughshinny areas, it will he clear that this 

 region was close to an old shore-line of the Carboniferous Lime- 

 stone sea. The actual position of that coast-line would of course 

 vary from time to time with the rise or fall of the land, but it 

 appears to have been situated almost parallel to and a short 

 distance seaward of the present coast-line between Rush and 

 Skerries, and then to have veered from Skerries westwards. Some 

 overlapping of deposits against the old sea-margin would take place 

 during periods of subsidence, while at times of elevation recently- 

 formed limestone would be exposed to the action of the waves and 

 be broken into those rounded masses that are found embedded in 

 the strata at various horizons in the series. All the deposits are 

 of marine origin, and for the most part they were formed in shallow 

 water ; there was, in all probability, considerable lateral variation in 

 the character of the deposits. 



The oldest beds — the Rush Slates — were laid down probably at or 

 near the mouth of a river that drained a region of dark Ordovician 



