442 SECTIONAL {TRANSACTIONS.—C. 
banded siltstones and mudstones containing abundant graptolites, which include 
M. bohemicus, M. colonus, M. dubius, M. uncinatus var. orbatus, M. salweyi, 
&e., belonging to the nilssoni-zone. 
Succeeding these are 900 feet of cleaved, striped, and current-bedded sandy 
flags with bands of calcareous mudstones (=Nant y bache of Dr. Wills), and at 
the top, fine sandstones. Graptolites are not common, and are badly preserved, 
but are of dubius and colonus types. | The sandstones occur as several thin 
bands, and are badly crumpled. The cleavage strikes approximately east-west, 
and dips north. 
About 1,200 feet of flaggy beds and mudstones overlie these beds. Cleavage 
becomes less pronounced, and practically disappears in the mudstones. The 
uppermost beds are flaggy and contain JM. tumescens and rarely M. scanicus. 
The mudstones contain M. dubius, M. colonus, Dayia navicula, Rhynchonella 
nucula, Acidaspis hughesi, &c. M. leintwardensis has not yet been found. 
The country is broken into blocks by normal faulting. The dominant 
system courses approximately north-south, with usually the downthrow to the 
east. A similar series of fractures throws down the Carboniferous and Trias 
on the eastern margin of the area, and forms the western boundary of the 
Vale of Clwyd. 
8. Prof. P. F. Kenpatu.—The Formation of Inter-lake Deltas. 
In the afternoon an excursion took place to North Wirral and 
Storeton Quarries. 
Saturday, September 15th. 
In connection with the general excursion to Lake Vyrnwy a geo- 
logical party, led by the President of Section C and Mr. W. B. R. King, 
visited sections in the Upper Ordovician and Lower Silurian rocks. 
Sunday, September 16th. 
A full-day excursion to Flintshire took place. (Holywell Shales, 
Carboniferous Limestones and Cherts, Glacial deposits, &c.) 
Monday, September 17th. 
9. Dr. R. L. Saertock.—The British Rock-salt Deposits. 
British rock-salt deposits are confined to the New Red rocks. Two areas 
are recognised: (1) a Western District containing the deposits of Cheshire, 
Lancashire, Isle of Man, North Ireland, Staffordshire, Worcestershire, and 
Somerset; (2) an Eastern District comprising Co. Durham and Yorkshire. 
In the Western District the rock-salt is in the Keuper Marl; in the Eastern 
District its age has been a matter of controversy, and it is described by different 
authors as Keuper or Permian. 
In the Western District there are frequently two beds of salt separated 
by a band of marl, as in Cheshire, Lancashire, North Ireland, Staffordshire, 
and Worcestershire. This leads to the conclusion that the two salt beds in 
these counties are contemporaneous, as probably are those of the Isle of Man 
and Somerset, where, however, the two beds have not been recognised. 
The Cheshire deposits occur in a Top and Bottom Bed separated by from 
20 to 45 feet of marl. The Top Bed is from about 30 to 90 feet thick, and 
the Bottom Bed from about 60 to 91 feet, the Top Bed being the more variable. 
This is in part owing to subsequent denudation. A recent investigation! indi- 
cates that the salt-field is much more extensive than had been supposed, 
covering an area of about 375 square miles. 
* R. L. Sherlock. Rock-salt and Brine. Special Reports on the Mineral 
Resources of Great Britain, vol. xviii., Mem. Geol. Surv., 1921. 
