126 



HENRY G. FERGUSON 



volcanic agglomerates and breccias, which contain small angular bits 

 of black glass or "palagonite." The material is absolutely unstrati- 

 fied, thus differing from the " jokullhlaup" sediments described below, 

 which show more or less distinct bedding. Dr. von Knebel, ^ how- 

 ever, describes indurated "jokullhlaup" sediments of the southern 



part of Iceland in terms 

 which would be equally 

 applicable to the beds I 

 here describe as moraines. 

 The basalt flows, aver- 

 aging about 25 feet in 

 thickness, are almost in- 

 variably brecciated near 

 the lower surface, strik- 

 ingly columnar in the 

 center, and vesicular near 

 the top. Where immedi- 

 ately covered by another 

 flow, the upper surface is 

 ropy. 



The section on the Sels- 

 fjall is best explained by 

 the accompanying illustra- 

 tions. In the main section (Fig. 3) it will be seen that there are 

 three morainal beds, usually covered by sandstone, instead of being 

 directly overlain by basalt. 



The lower ground-moraine is about 20 feet thick, and has no 

 overlying sandstone. In consequence of being directly overlain by 

 the basalt, the upper 3 or 4 feet of the bed are so thoroughly baked 

 that the pebbles break off even with the matrix. 



The second moraine, at the point shown in the section, is almost 

 hidden by the talus. A few feet above the moraine is a small out- 

 crop of a much contorted tufaceous sandstone. This contortion 



I Dr. Walther von Knebel, "Vorlaufige Mitteilung liber die Lagerungsverhaltnisse 

 glazialer Bildungen auf Island etc.," CentralUatt fiir Mineralogie Geologic und 

 Paldontologie, Jahrgang 1905, No. 17-18, p. 539. See also, H. Pjetursson, " Das 

 Pleistocan Islands," CentralUatt fur Mineralogie, Geologie und Paldontologie, Jahrgsmg 

 1905, No. 24. 



Fig. 4. — Lower moraine and overlying basalt. 



