Ordovician and Silurian Rods of Kilbride Peninsula. 811 



existing, with references to the descriptions in the Survey Memoirs 

 and notes of those that are there undescribed. 



The paper gives an account of a series of sands and silts, which 

 lie at about 200 O.J), on each side of the present Stour Valley. 

 They seem to indicate shallow-water conditions at a level more 

 than 100 feet above the present valley-floor. 



On the silts lies Chalky Boulder Clay. The transition from silt 

 to clay is continuous, and seems to show that, here, the transition 

 from formation of silt to formation of Boulder Clay was a con- 

 tinuous transition. The undisturbed condition of the beds indicates 

 that during this transition there was no action of thrust or drag. 



At lower levels, from 180 O.D. down to 100 O.D., on the 

 fl auks of the valley lie coarse gravels and sands, with current- 

 bedding, which point to torrential water-action. Among these 

 occur displaced masses of previously-formed Boulder Clay, some, 

 contorted — as if by slip down slopes. At Little Cornard brick- 

 works there is associated with current-bedded gravels a clay, in 

 which are embedded very large masses of remade Chalk. 



The deduction from these facts is that at Sudbury, Boulder Clay 

 began to be formed where there was quiet water, which stood on 

 both sides of the valley at a level of over 120 feet above the 

 present floor : and that, after such Clay had been formed, there 

 came to be strong currents into or along the valley, at various lower 

 levels. 



These deductions agree with the probable course of events, if 

 a submergence preceded the Chalky Boulder Clay and an emergence 

 followed it. 



2. ' The Ordovician and Silurian Rocks of the Kilbride Peninsula 

 (County Mayo).' By Charles Irving Gardiner, M.A., F.G.S., and 

 Prof. Sidney Hugh Reynolds, M.A., F.G.S. 



The Kilbride peninsula includes three principal groups of rocks. 

 The northern and western part is, in the main, composed of igneous 

 rocks, contemporaneous and intrusive, of Arenig age ; the southern 

 and eastern part principally consists of Silurian rocks, but these 

 are in the south-eastern corner of the peninsula faulted against an 

 area of gneiss. The Arenig rocks resemble the Mount Partry Beds 

 of the Tourmakeady and Glensaul districts — in the fact that they 

 include cherts and shaly beds with Didy-moc/raptus extensus, and in 

 the presence of gritty tuffs and coarse breccias, the latter rocks 

 showing a magnificent development. No coarse conglomerates, 

 however, occur, and no limestone-breccias or other representatives 

 of the Shangort Beds of Tourmakeady and Glensaul, while Arenig 

 sediments of all kinds are very scarce. The most interesting 

 feature of the Arenig rocks is the great development of spilitic 

 lavas, which are commonly associated with cherts and often show 

 good pillow-structure. Their resemblance to the similar rock of 

 the Girvan district is very close. An enormous mass of felsite 

 with large quartz-phenocrysts, and often albite, as also pseudo- 

 morphs after rhombic pyroxene, occupies much of the northern 



