Geological Society of London. 



381 



13. " On a Section of Boulder-clay and Gravels at Ballygalley 

 Head, and an inquiry as to the proper classification of the Irish Drift." 

 By T. Mellard Reade, Esq., C.E., F.G.S. 



The section described is in a gravel-pit about 30 feet deep, situated 

 between Larne and Cushendall, in the north of Ireland. It shows 

 a considerable thickness of false-bedded gravel and sand, containing 

 shells, covered by Boulder-clay. The shells collected from the sand 

 and gravel of this section do not, however, agree with those found in 

 the so-called " Interglacial beds" of Lancashire; and the author 

 regards the section as confirming his views that the tripartite division 

 of the drift- deposits is not, as maintained by Hull and other geologists, 

 equally applicable to the Irish and Lancashire deposits. 



14. " On the Augitic Rocks of the Canary Islands." By Professor 

 Salvador Calderon. Communicated by the President. 



As the result of a long investigation of the eruptive rocks of the 

 Canaries, and especially of Las Palmas, the author has come to the 

 conclusion that there are two groups of such rocks in those islands, 

 an older one, characterized by the presence of hornblende, and a 

 newer, containing augite. In the latter he finds the essential minerals 

 to be plagioclase, augite, magnetite, olivine, sanidine, and nepheline ; 

 and he distinguishes among them the following kinds of rocks, all of 

 which have their characteristic minerals imbedded in a paste of augite 

 and plagioclase: — 1. Augite-andesite, with a small quantity of sani- 

 dine ; 2. Tephrine, with no sanidine, but abundance of nepheline ; 

 3. Bascmite, with some peridote ; 4. JYepheline-basalt, with abundance 

 of peridote; 5. Dolerite, crystalline, characterized by the disappear- 

 ance of nepheline, the abundance of peridote and porphyritically im- 

 bedded plagioclase, and with porphyritically imbedded individuals of 

 augite and olivine ; 6. Felspathic basalt (like 5), but sernicrystalline ; 

 and 7. Essentially olivinic modern lavas. 



15. "On the Cambrian (Sedgw.) and Silurian beds of the Dee 

 Yalley, as compared with those of the Lake-district." By J. E. Marr, 

 Esq., B.A., F.O.S. 



The principal differences in these districts appear to be due, 



(1) to the non-correspondence of the epoch of volcanic activity, 



(2) to the upheaval and consequent denudation of a part of North 

 Wales after the end of the Cambrian period. The author correlates 

 the deposits in the two areas, the Dee valley having deposits parallel 

 to the various members in the Lake-district, from the Skiddaw Slates 

 to the Upper Coldwell beds inclusive. The Lower Bala series contains 

 ash-beds which appear to be andesitic. In the Middle Bala of Wales 

 are some fossils which, in the Lake-district, occur in the Ashgill 

 Shales above the Coniston Limestone. He finds the equivalents of the 

 Graptolitic Mudstone of the Lake-district, near Carrig-y-druidion, 

 corresponding in stratigraphical position, lithological character, and 

 fossils. One Graptolite, G. colonus, however, occurs at a higher 

 horizon in the Lake-district. In the lowest division of the Denbigh 

 Grits Aeroadia haliotis is found, which, in the Lake-district, occurs in 

 the Upper Coldwell beds ; and in the uppermost series there are other 

 fossils which occur in the Bannisdale Slates and Kirkby-Moor Elags, 

 thus giving further indications of a northward migration. 



