Yol. 55.] GLACIAL PHENOMENA OF SPITSBEKGEN. 689 



impressed on them in former times. The presence of boulders of 

 diabase on the plateaux of Sticky Keep in the ice-free Sassendal at 

 an elevation of 1500 feet, where they must either have been raised 

 nearly 1000 feet, unless the valley has since been excavated to that 

 depth, or carried up on the surface of a glacier which attained that 

 thickness, not to quote other instances observed on the island, is a 

 sufficient proof of the former much greater extent and thickness of 

 the ice in the district. 



EXPLANATION OF PLATES XLI-XLVIII. 

 Plate XLI. 



Outline-map of Central Spitsbergen, on the scale of about 14 miles to the 

 inch, showing the radiating-points of the inland ice. 



Plate XLII. 



Panoramic view showing the main ice-streams entering the eastern end of 

 King's Bay. 



The ice in the immediate foreground is derived from the local glaciers at the 

 foot of Mount Neilson. Its motion is slow, it is uncrevassed, and it terminates 

 on a flat of raised-beach material. The bulk of the glacier beyond (Crowns 

 G-lacier) is derived from the Highway Glacier and the ice-sheets north and west 

 of the Pretender Range. Its motion is much slower, and it terminates in a 

 vertical face from which icebergs are calved. The estimated advance of the 

 main mass is 25 to 30 feet in 24 hours. 



The mountain-ranges extending across the island from Mount Neilson are 

 composed of Hekla Hook Beds, and form the southern boundary of the King's 

 Highway. The range marks a line of thrust against which patches of Car- 

 boniferous rocks have been let down, and this thrust-plane no doubt determined 

 the original direction of King's Bay. Views obtained from the summit of 

 Mount Neilson show that the country south of the range is mountainous, and 

 not covered with an ice-sheet as indicated on the chart. 



The centre of the view is occupied by two nunatakkr. The larger of these, 

 on the right, is formed of Carboniferous Limestone, exhibiting a thrust-plane 

 between the lower and upper beds. The more distant nunatak, on the left, is 

 of Devonian conglomerate similar to that of which the islands in the bay are 

 formed. 



Plate XLIII. 



The terminal front of King's Grlacier : the thickness of the ice showing above 

 sea-level is about 100 feet. 



I = South-east Islands (see panorama, Pi. XLII). 



M=Englacial moraine, elevated and thrown out at the end of Neilson Glacier, 

 about 50 or 60 feet above sea level. 



Plate XLIV. 



Icebergs calved from King's Glacier at half-tide. View taken at midnight, 

 looking south-east from vthe north-west islands of Devonian conglomerate 

 shown in the panorama (PI. XLII). 



The undulating shore-line AB is formed of Permo-Carboniferous dolomitic 

 limestone, and the thrust-plane already mentioned runs between it and the 

 mountain-range. From the icebergs shown in this plate the approximate 

 rate of motion of King's Glacier was deduced. Moraine-material is con- 

 spicuously present on many of them, and some of it can be seen stranded in 

 the foreground. Boulders from this showed the characteristic unilateral 

 striation to which reference is made on p. 687. Attention is also directed to 

 the Corrie Glacier, examples of which were described in a former paper, Quart. 

 Journ. Geol. Soc. vol. liv (1898) p. 200. 



