100 



J. S. GAEDNER ON THE TEETIARY 



small valley, marked Sandklettavatn, about lat. 64° 21', between 

 Keykbolt and Thingvalla. It is marked as a lake without any. outlet ; 

 but in August there was only a little water at one end, the stream 



Fig. 4. — Cliff and Bavine about 7 miles from Hofsgil, 

 height about 1000 ftet. 



-'5^^^ 



a. Boulder-clay. a'. Boulder-clay weathered into architectural forms. 



b. Basalt. h'. Basalt with partiugs of bright red and brown earth. 



c. Ehyolite. d. Sedimentary rocks, about 130 feet, chiefly yellow and 



drab sandstones, with two intercalated bands of lignite, marked **. 



connecting it with Ukavatn being also dry. The plain is level, 

 destitute of vegetation, about three miles long and one broad, closed 

 in on three sides by mountains and on the fourth by a lava-stream. 

 Its shores are regularly terraced all round, the terraces being only 

 2 or 3 feet high. It is evidently a shallow lake for a great part of 

 the year, and the terraces have some connexion with the recurring 

 formation and disappearance of a dam of snow or ice at its eastern 

 extremity. 



