Reports ctj Proceedings — Geological Society of London. 137 



latter have fortunately escaped cleavage, and some mudstones in the 

 midst of the series have yielded a nuraher of fossils helonging to 

 the zone of Paradoxides hicJcsi. The P. davidis zone appears to be 

 absent, as the result of a sliglit unconformity. 



This southern area of relatively simple structure is separated by an 

 overthrust of considerable magnitude from a more northern area in 

 which members of the Tremadoc, Arenig, and Llandeilo Series have 

 been recognized, but in which the rocks are highly crushed, faulted, 

 and disturbed, and the relations between the beds are fur from clear. 



The general succession is — 



South of the Thrust. 



Llanengan Mudstones. ^ 



Tudwal Sandstones and j 

 Grits. j 



(Zone of Didiimograptus 

 extens'us.) 



Great unconformity. 



Llandeilo. 



Llanvirn. 



Arenig. 



Tremadoc. 



dolgelly. 

 Ffestiniog. 



North of the Thrust. 

 Hen-dy-Capel Mudstones. 

 (Zone of Nemagraptus 

 gracilis.) 



Benar Beds. 



(Zone of Didymograptus 



extensus ?) 

 Probable unconformity. 



Abersocli Beds. 



Ffestiniog Beds. 



(Only in East St. Tudwal's Island.) 

 Maentwrog Beds. Maentwrog. 



Probable unconformity. 

 Nant-pig Mudstones. Menevian (of Merionethshire). 



Caered Mudstones and Flags. ^ 



Cilan Grits. I Harlech Grits (of Merionethshire), 



Mulfran or Manganese Beds. I (in part). 

 Hell's Mouth Grits. j 



Base not seen. 



Pisulitic ircm-ore is well developed in the district, and occurs chiefly 

 in the Landeilo Beds along the line of the overthrust; it is regarded 

 as of sedimentary origin. Tlie glacial geology is only briefly dealt 

 with ; but evidence is presented to show that, during the last phase 

 of glaciation, the ice was moving across the peninsula in a westerly 

 direction out of Cardigan Bay. 



2. January 21, 1914.— Dr. Aubrey Strahan, F.R.S., President, 

 in the Chair. 



The following communications were read: — 



1. "Geology of the Countrv round Huntly (Aberdeenshire)." By 

 William Robert Watt, M.A., H.Sc. F.G.S. 



In this area two distinct series of rocks can be distinguished — 

 a foliated and a non-foliated series. In the former occur rocks 

 originally sedimentary and others originally igneous. In the non- 

 foliated series, which is wholly of igneous origin, three main 

 intrusions occur : — 



(1) The earliest and most extensive is a norite with, as modifica- 

 tions due to diflferentiation, olivine gahhros, troctolites, and 'picrites'. 



