372 Geological Society. 



of Dolgelly.' By Philip Lake, Esq., M.A., F.G.S., and S. H. Key- 

 nolds, Esq., M.A., F.G.S. 



The area dealt with in this paper lies south and west of 

 Dolgelly, between the Arthog road and the hill called Mynydd 

 Gader, which lies in front of the precipices of Cader Idris. The 

 stratified rocks belong to the Middle and Upper Lingula-Fl&gs and 

 Tremadoc Slates. The Middle Lingula-~F\?Lg$ (Ffestiniog Series) 

 consist of bluish slates with grit-bands containing the usual Lingu- 

 lella, passing into Upper Lingula-Flags (Dolgelly Series) consisting 

 of dark slates with Orthis lenticularis, Parabolina spinulosa, etc., 

 and containing two andesitic lavas. These pass into the basal 

 Tremadoc Slates with Dictyograptus flabelliforrnis, surmounted by 

 an upper volcanic series with rhyolitic lava. Subsequent intrusions 

 of diabase occurred, of a laccolitic character, but of such a nature as 

 to lead the authors to suggest the possible intrusion of the diabase 

 along a line of unconformity in one case ; there is, however, no 

 newer rock above the diabase to indicate of what date the overlying 

 beds would be if such unconformity occurred. It is further shown 

 that the important faults in the area were produced both before 

 and after the diabase-intrusions, and in one case the movement 

 appears to have been in one direction before the intrusions, and in 

 the opposite direction afterwards. 



3. ' The Kildare Inlier.' By S. H. Keynolds, Esq., M.A., F.G.S., 

 and C. I. Gardiner, Esq., M.A., F.G.S. 



The area described in this paper is occupied by four prominent 

 hills composed of Lower Palaeozoic rocks rising as an inlier from 

 beneath Carboniferous beds. The authors give the following suc- 

 cession of rocks in descending order : — 



6. Green and grey micaceous grits and shales of Dunmurry. 

 5. Red and black shales. 



Gap : no exposure seen. 

 4. Limestones of the Chair of Kildare. 

 3. Contemporaneous igneous rocks. 

 2. Possiliferous ash of Grange Hill House. 

 1. Green gritty shales (unfbssiliferous). 



Nos. 5 and 6 are referred with some doubt to the Llandovery 

 Series, and perhaps also to higher series. The gap may conceal the 

 uppermost beds of the Bala succession. The limestones of the 

 Chair of Kildare are separated by the authors into four subdivisions 

 of the same general age, and Agnostus trinodus, Illoenus Boivmarwi, 

 Remopleurides longicostatus, and Cyphoniscus serialis range through- 

 out. The contemporaneous igneous rocks of Grange Hill and of the 

 Hill of Allen are shown by the fossils found in the pyroclastic rocks 

 to be of Middle Bala age. The lavas consist of basalts and andesites 

 which the authors separate into four groups distinguished by their 

 lithological characters. Petrographical details of these various 

 rocks are given in the second part of the paper. The age of the 

 lowest beds which have not yielded any fossils is doubtful. 



