Heports and Proceedings — Geological Society of London. 179 



snperglacial and intraglacial streams, so far as seen, were usually 

 clear of drift. Under the fourth head an esker in a tributary of the 

 Sassendiil is described. 



The direct geological action of the marine ice is of four kinds : 

 transport of material, contortion of shore-deposits, formation of small 

 ridges of boulder-terraces above sea-level, and striatiou, rounding, 

 and furrowing of rocks along the sea-shore. 



Traces of former glaciation are described in the case of the Hecla 

 Hook beds, and of certain beds of late Mesozoic or early Cainozoic 

 age in Bunting Bluff. 



Under the head of general conclusions, the authors state that they 

 have discovered no certain test to distinguish between the action of 

 land-ice and marine ice ; that there is no evidence to prove that 

 land-ice can advance far across the sea; and tliat there is evidence, 

 which they regard as conclusive, of the uplift of materials by 

 land-ice. They note that the mechanical processes connected with 

 the advance of the glaciers are of three kinds. All the material 

 seen transported by the glaciers was snperglacial or intraglacial, and 

 not subglacial. Some striation of intraglacial material is caused by 

 differential movement of different layers of ice. The advance and 

 retreat of the Spitzbergen glaciers is very irregular, and apparently 

 due to local changes. The observations of the authors support the 

 views of those who ascribe a limited erosive power to glaciers. 

 Lastly, the theory that glacial periods occurred as a consequence 

 of epeirogenic uplifts receives no support from Spitzbergen. 



2. " On a Quartz-rock in the Carboniferous Limestone of Derby- 

 shire." By H. H. Arnold-Bemrose, Esq., M.A., F.G.S. 



The paper describes the occurrence in the field and the micro- 

 scopic structure of a rock consisting essentially of quartz, which is 

 found in the Mountain Limestone in several localities. It occurs 

 in irregularly-shaped bosses and veins, and shows no signs of 

 stratification. 



Its close association with a quartzose limestone, which in turn 

 passes into an ordinary limestone with few, if any, quartz-crystals, 

 leads to the inference that it is a silicified limestone. 



The microscopical structure of a number of thin slices of these 

 rocks is described. The quartz-rock is seen to be made up of 

 quartz-grains which generally interlock closely, but sometimes 

 possess a crystalline outline and contain zones of calcite. Fluor 

 is occasionally present. 



The quartzose limestone is usually a foraminiferal limestone 

 containing a large percentage of quartz, which occurs as separate 

 crystals and as aggregates of crystals. The latter and the small 

 quartz-veins have a structure similar to that of the quartz-rock. 

 The former often contain zones of calcite and penetrate organisms. 

 The residue consists of quartz-crystals. 



The author considers that the quartz-rock is not a gritty lime- 

 stone, altered by the growth of crystalline quartz around the detrital 

 grains, but that it is a limestone replaced by quartz. The gradual 



