Vol. 68.] PEE-CAMBEIAN AND CAMBKIAN OF PEMBROKESHIRE. 401 



Hicks's work in South Wales had been finally verified, and that 

 the terms Pebidian and Dimetian were to be restored. 



Hicks at first regarded the Dimetian as an intensely altered 

 sediment which showed only the last traces of the original bedding, 

 a view held at that time by many geologists. It has since proved 

 to be a granitic rock, the apparent bedding being due to a foliation 

 which was produced either during or after consolidation. 



After working for some years in South Wales, Hicks visited the 

 Highlands and reopened the question of the upward succession. 

 Here he again recognized his Dimetian, both at Loch Maree in the 

 Lewisian Gneiss, and to the south-east of the Moine Thrust. He 

 also noted here the peculiar type of flinty rock associated with the 

 Dimetian, which we now know to be due to the contact-action of 

 the igneous rock. The speaker, twenty-five years ago, recognized a 

 similar rock, also in association with the flinty material, at the 

 southern end of the Highlands (the Ben Vuroch augen-gneiss in 

 Perthshire). This intrusion cuts both the Central Highland 

 Quartzite and the Limestone, which thus are older than part at 

 least of the Lewisian Gneiss. 



, Prof. 0. T. Jones, replying on behalf of the Authors, thanked the 

 President and Fellows for the reception given to their paper. 



In answer to Mr. Green, he stated that there could be no question 

 as to the magnitude of the pre-Carboniferous movements in the 

 district. The base of the Carboniferous rocks had been proved 

 by the officers of the Geological Survey to overstep successively 

 Old Red Sandstone, Silurian, and Ordovician rocks ; also big 

 faults, which occurred at and near the southern margin of the 

 area described, were not continued into the Carboniferous rocks. 



