140 Reports and Proceedings — Geological Society of London. 



by Dr. Eeusch, a heterogeneous mixture of grit and clay with 

 boulders of granitic and other rocks is seen to be intercalated 

 between the quartz-grits, the bedding of the overlying grit proving 

 that this boulder-rock was contemporaneously formed, and not 

 subsequently wedged in. The surface of the grit below the rock 

 is characteristically glaciated. Proof is given that the striated 

 surface is not the floor of a thrust-plane, and that the boulder-rock 

 is not a fault-breccia or a crush-conglomerate, but a " till." In the 

 absence of fossils the Gaisa formation is doubtfully assigned to an 

 early Palaeozoic age. It exhibits the same sedimentary characters 

 as the rocks of later date in other parts of the world in which glacial 

 phenomena have been observed. The glacial episode is attributed 

 to a temporary change of climate rather tlian to the high latitude in 

 which the section lies. 



2. "The Eaised Beaches and Glacial Deposits of the Yaranger 

 Fiord." By Aubrey Strahan, Esq., M.A., F.G.S. 



The Eaised Beaches range up to nearly 300 feet above the sea. 

 Though a number of impersistent shingle-banks occur at various 

 heights, the highest is constant, and can be traced along the same 

 level either as a shingly terrace or by a zone of wave-worn rocks. 

 Evidence is furnished by the relative size of different parts of the 

 beach that the prevalent wave-action was from the west, and by 

 the greater abundance of erratics on or below the beach than above 

 it, that floating ice was at work. 



At the head of the fiord a blue clay dotted over with stones is 

 now being formed, and the raised beach there consists of a similar 

 material. Both here and elsewhere this clay simulates a Boulder- 

 clay ; but for reasons given it is believed to be a marine fiord- 

 deposit, into which many stones have been dropped by floating ice. 



Deposits of true glacial age, in the form of mounds of gravel, are 

 described, and shown to have yielded the material out of which 

 parts of the Eaised Beaches are formed. The glaciation of the fiord 

 is attributed to floating ice, and is shown to have taken place before 

 the formation of the Eaised Beaches, at a time when the sea sur- 

 rounded this part of Finmark, by way of the Varanger Fiord, the 

 Tana Valley, and the Tana Fiord. 



II.— February 3, 1897. — Dr. Henry Hicks, F.E.S., President, 

 in the Chair. The following communications were read : — 



1. " The Subgenera Petalograptus and Cephalograptns." By Miss 

 G. L. Elles. (Communicated by J. E. Marr, Esq., M.A., F.E.S., 



F.G.S.) 



The forms referred to in the paper are accepted as subgenera of 

 Diplogra'ptus, as defined by Lapworth. The two subgenera have 

 frequently been much confused, but examination of specimens pre- 

 served in relief shows that they have very distinctive characters, 

 especially at the proximal ends. The author gives diagnoses of the 

 two subgenera, and detailed descriptions of the following forms : — 



