Vol. 5 5. J PROCEEDINGS OF THE GEOLOGICAL SOCIETY. Xci 



pebble-bed (' Packungstheorie ' of Berendt), and (4) action of wind 

 and sand. The last explanation was the only one that met the facts 

 of the case, as proved by A. von Mickwitz, Mem. Soc. Imp. Mineral. 

 St. Petersb. ser. 2, vol. xxii (1887) pp. 82-98, pis. viii & ix. 



In illustration of his remarks, Mr. Bather exhibited a series 

 of specimens which had been collected under the guidance of 

 A. von Mickwitz from the locality described by that author (shore 

 of the Obersee, south of E,eval, Esthonia). They confirmed the 

 statement that the three sides of the pyramids lay at right angles 

 to the directions of the prevailing winds of the district; they 

 showed stages between stones eroded on one face, or on two faces, 

 and the typical ' Dreikanter ' ; they illustrated the polishing action 

 of the agent on hard, fine-grained material, its differentiating 

 action on coarse-grained ; they retained the original waterworn 

 surface and shape on the under side, and a growth of lichen on 

 such small portions of the upper surface as had been sheltered 

 from the wind. Applying this explanation to Mr. Darbishire's 

 specimen, there still remained an unsolved problem : Was the 

 pebble eroded before or during the deposition of the Bunter 

 stratum, or at some time before, during or subsequent to the 

 transport and deposition of the Drift? The mode of occurrence 

 of the jN'orth German specimens shows that they were eroded after 

 the deposition of the beds at the top of which they now lie ; and, 

 in the absence of contrary evidence, the same answer must be 

 given provisionally to the preceding questions. 



The following communications were read : — 



1. ' On the Geology of Northern Anglesey.' By C. A. Matley, 

 Esq., B.Sc, E.G.S. ; with an Appendix on the Microscopic Study of 

 some of the Eocks, by Prof. W. W. Watts, M.A., Sec.G.S. 



2. 'On an Intrusion of Granite into Diabase at Sorel Point 

 (Northern Jersey).' By John Parkinson, Esq., E.G.S. 



In addition to those described on pp. xc and xci, the following 

 specimens, etc., were exhibited : — 



Rock-specimens, Microscope-sections, and Photograph, exhibited 

 by C. A. Matley, Esq., B.Sc, E.G.S., and Prof. W. W. Watts, M.A., 

 Sec.G.S., in illustration of their paper. 



Rock-specimens and Microscope-sections, exhibited by John 

 Parkinson, Esq., E.G.S., in illustration of his paper. 



A portion of an Ammonite from Cromer Beach, below the great 

 slip (Easter 1898), exhibited by A. E. Salter, Esq., B.Sc, E.G.S. 



Geologische Karte der im Reichsrathe vertretenen Kdnigreiche und 

 Lander der Oesterreichisch-Ungarischen Monarchic : 75^, Lief. 1 

 & 2, 1898. Presented by the Director of the Imperial Austro- 

 Hungarian Geological Survey. 



VOL. LV. 



