258 THE GEOLOGY OF NORTHERN ANGLESEY. [May I9OO, 



below. One of the slides also that had been shown on the screen 

 seemed to represent a most typical agglomerate ; so that he doubted 

 very much whether the group which the speaker had called the 

 4 volcanic group ' could have been possibly produced by normal 

 deposition and dislocation. The association of limestone, or ophi- 

 calcite, with serpentine was seen elsewhere in the island, and 

 appeared to be a not unnatural result of the subjection of the latter 

 to strain, with subsequent access of heated water. 



Mr. Barrow called attention to > the close resemblance of these 

 rocks with those already found by Mr. Greenly in Anglesey, and also 

 with those occurring along the Highland Border in Kincardineshire 

 and shown on Sheet 66 of the Geological Survey map of Scotland. 

 Mr. Peach had suggested that these Scottish rocks were of Arenig 

 age, as they bore a singular likeness to the basic igneous rocks 

 and associated cherts of the Southern Uplands. The map shown 

 by the Author suggested a belt of overthrusting, and that had proved 

 to be the relation of the Highland schists to the Border rocks of 

 doubtfully Arenig age. With regard to the limestone of doubtful 

 origin, it might be worth noting that at Garron Point, near Stone- 

 haven, a thick dyke-like mass of ferruginous dolomite had formed in 

 the line of the Highland Fault, and there could be no doubt that 

 this calcareous rock was due to the material set free by crushing 

 the minerals in the mass of basic igneous rock of supposed Arenig 

 age which occurs close to the Fault. 



Mr. Greenly congratulated the Author upon his results, which 

 would certainly be of great value in the future investigation of 

 that difficult region. With regard to the Llanbadrig Series, he 

 thought it highly probable (although he had not yet worked in the 

 north of Anglesey) that these rocks would prove to be identical with 

 a group of rocks that he had traced for some miles in other parts of 

 the island. The behaviour of these quartzites and limestones was 

 certainly anomalous, and might prove to be not wholly, though still 

 very largely due to crust-movements. The characters of the dykes, 

 diagrams of which had been shown upon the screen, did not 

 appear to resemble those of the later dykes of the island, which 

 had been hitherto regarded as of post-Carboniferous, but pre-Permiau 

 age. 



The Author thanked the speakers for the kind way in which 

 they had received the paper. With regard to the numerous faults 

 shown on the map, many were revealed by the coast-sections, others 

 were necessitated by the stratigraphy, and some were inferred. He 

 quite agreed with Mr. Greenly that the quartzites were very puzzling, 

 and looked forward to very important results from the latter's own 

 field-work in Anglesey. The lithological resemblance pointed out 

 by Mr. Barrow of some of the Anglesey rocks to those of the 

 Highland Border was interesting. Some day it might be possible 

 to attempt a correlation of these widely-separated areas. 



