76 REPORT — 1875. 



been free from coarse sand, <and that the sand by which the stones became enve- 

 loped was tranquilly introduced. He opposed the idea that the sand was derived 

 by fresh water from the boulder-clay on the platform above the cave. 



Queries and HemarJcs relative to existing Ice-action in Greenland and the 

 Alps, compared ivith former Ice-action in the N.W.of Enr/land ami Wales. 

 B>j D. Mackintosh, F.G.S. 



The author begins by discussing the question whether the so-called continental 

 ice of Greenland be a true ice-sheet formed independently of mountains, or merely 

 an exaggeration of a confluent system of glaciers. [Tliis and several other ques- 

 tions, furnished by the author, were incorporated with the Instructions for the 

 Arctic Expedition.] He then goes on to consider the state of the surface of the 

 Greenland ice-sheet, and believes that the amount of moraine matter is locally 

 limited and of small extent. In querj^ 3 he defends the idea of the internal purity 

 of existing ice-sheets ; and in query 4 he states reasons for doubting whether 

 glaciers are capable of persistently pushing forward the large stones they may find, 

 in their beds, though he admits that the base of glaciers is charged with finer 

 debris by means of which tliey grind and striate rock-surfaces. He mentions that 

 in tlie Lake-district he had never seen a sharply bordered groove on a glaciated 

 rock-surface which might not have been produced by a stone smaller than a walnut. 

 He then quotes Forbes and Lyell to tlie eftect that scarcely any of the stones found 

 in the moraines of existing Alpine glaciers are polished or striated ; and this leads 

 him to ask, in query 6, whether the base of the Greenland ice-sheet be capable of 

 holding"Jstones firmly fixed in its grasp. He states reasons for doubting this ; and 

 after referring to the paucity of umformly striated small stones among tlie mountains 

 of the Lake-district and Wales, which once must have been covered with an ice- 

 sheet or ice-sheets, compared witli the abundance of regularly glaciated small 

 stones in the boulder-clay of the neighbouring plains, he proceeds to consider the 

 geological action of icebergs, and believes that they carry more roclvy d(5bris in 

 their base than on their surface. In query 10 he considers whether grounding ice- 

 Ijergs can give a roimded form to submarine rocks, or glaciate do-uTihill ; and 

 states reasons for believing that they can do so to a certain extent, but that dome- 

 shaped roches mmdonnees have been principally formed by land-ice. He sees no 

 reason for doubting that revolving icebergs are capable of scooping out hollows in 

 the rocky bottom of the sea, and thinks that lake-basins on the rocky summits of 

 hills, or on waterslieds, may have been produced in this waJ^ He then gives 

 reasons for supposing that the drift-knolls called cakers, where their forms are very 

 abrupt, may have been partly formed by eddying currents or waves generated or 

 intensified by ice-movements, which sometimes will set the sea in motion as niucli 

 as sixteen miles off". 



The principal and most original part of the paper is on the subject ot coast-ice. 

 The author brings forward a mass of testimony, accompanied by considerations 

 which tend to show that floating coast-ice is the principal transporter and glaciator 

 of stones, and that the uniformly striated stones found in the boulder-clay of the 

 plains were both glaciated and transported by coast-ice. He enters minutely into 

 a consideration of how stones, previously more or less rounded, became flattened 

 and uniformly grooved on one, two, or more sides, the grooves on each side varying 

 in their dii-ections. He believes that manj' of the stones found in the boulder-clay 

 of Cheshire must have been frequently dropped and again picked up by coast-ice 

 during the passage from their original positions. 



On certain Isolated Areas of Mountain-Limestone at Luclcington and Yohster. 



By J. jyPMuETEiE, F.G.S. 



In a few introductory remarks the writer described the general structure of the 

 Carboniferous rocks of Somersetshire, together with their relation to the older rocks 

 on which they rest, and the secondary formations by which they are overlaid. He 



