948 . Geological Society : — 



June 23rd.— Mr. R. D. Oldham, F.R.S., President, 

 in the Chair. 



The following communication was read : — 



'The Scandinavian Mountain Problem.' By Olaf Holtedahl. 



In the introduction a brief account is given of the history of 

 research regarding the Scandinavian mountain problem, which 

 deals with the superposition of highh -metamorphosed, often 

 gneissose rocks upon slightly-altered fossiliferous Cambro- Silurian 

 sediments. 



From a consideration of the phenomena in the mountain-belt of 

 deformation, it is inferred that the age of the displaced materials 

 depends upon the angle of inclination of the thrust-planes and 

 their depth. Though the thrusts have extended downwards for 

 a considerable distance, they have not, generally, in the author's 

 opinion, reached below the level of the pre- Cambrian plane of 

 denudation, and no true Archaean rocks could, as a rule, have been 

 tapped. 



In support of these conclusions some of the tectonic features of 

 two districts are indicated : (1) Finmarken in Northern Norway, 

 and (2) the southern part of the Sparagmite area near Randsf jord, 

 in South- Central Scandinavia. Brief descriptions are given of the 

 rock-groups in Finmarken and their structural relations. Special 

 attention is directed to the structure of the Alten district, where 

 the main tectonic feature is a highly-undulating thrust which does 

 not intersect the pre-Cambrian floor. Regarding the Randsfjord 

 district, the original order of succession of the strata is indicated, 

 from the Holmia Shale to the close of the overlying Cambro- 

 Silurian sediments. Pressure from the north in late Silurian time 

 developed imbricate structure in these sediments, but such dis- 

 placements are not supposed to have affected the pre-Cambrian floor. 



As investigation proceeds, it seems to become increasingly 

 evident (1) that the highly-metarnorphic sedimentary rocks of the 

 middle and northern part of the eastern mountain-belt are mainly of 

 earlier Ordovician age, while those west of the Sparagmite region 

 in the south-western mountain district are chiefly of Silurian age ; 

 and (2) that the igneous materials associated with these highly- 

 metamorphosed sediments are } T ounger intrusive rocks. 



December 1st.— Mr. R. D. Oldham, F.R.S., President, 

 in the Chair. 

 The following communication was read : — 



'An iEolian Pleistocene Deposit at Clevedon (Somerset).' By 

 Edward Greenly, D.Sc, F.d.S. 



Banked up against the craggy hillsides about Clevedon are 

 considerable deposits which contain a terrestrial molluscan and 

 vertebrate fauna of Pleistocene age. Most of the vertebrates were 

 obtained from a small cave, during exploration some years ago bv 

 Mr. G. E. Male & Prof. S. H. Reynolds. The deposits consist of 

 sandy breccia, stony sand, loamy sand, and loam. Breccias occur 

 only close to the crags, but the sands may extend all across the 

 valleys. The stones, which are sharply angular, are of exclusively 



