790 H. S. WASHINGTON DECCAN SALTS AND PLATEAU BASALTS 



1. Hebrides, etc. ; 7 analyses. 



2. Faroes ; 2 analyses. 



3. Iceland; 5 analyses. 



4. Greenland; 3 analyses. 



5. Jan Mayen ; 1 analysis. 



6. Spitzbergen ; 13 analyses. 



7. Franz Josef Land ; 2 analyses. 



8. Average of Thulean basalts. 



As Holmes remarks, "the outstanding features of the Arctic (Thulean) 

 basalts are low silica, alumina, and alkalies and high titanium dioxide, 

 iron oxides, and lime." They thus show the main chemical features of 

 the Deccan and Oregonian basalts; but it is to be noted that the total 

 amounts of iron oxides are rather lower than in the last, while there is a 

 somewhat greater amount of ferric oxide relative to ferrous, this being 

 due possibly to the slightly altered condition of some of the specimens. 

 The excellent analyses by Harwood are of great value in showing the 

 general presence of notable and constant amounts of chromium and 

 vanadium, which is corroborated by the figures by Pollard and Eadley 

 for Scottish basalts and those of Dittrich for chromium in Spitzbergen 

 basalts. The percentage of titanium dioxide is generally very high, and 

 Holmes devotes considerable space to discussion of the inverse variation 

 between titanium and the feldspars. 



It is scarcely necessary to give here the norm of each of the average 

 analyses above, so that only the norm of the general average of the 

 Thulean region is shown here. 



Table X 



Norm of Thulean Basalts 



Quartz 0.84 



Orthoclase 5 . 56 



Albite 23.06 



Anorthite 23.91 



Diopside IS . 14 



Hypersthene 12 . 86 



Magnetite 5 . 57 



Ilinenite 7 . 45 



Apatite 1.01 



Symbol III. 5. (3)4.4. 



The close general correspondence between this norm and those of the 

 Deccan and Oregonian basalts will be evident at a glance. We see the 

 same tendency toward an excess of silica, in spite of the general Thulean 

 rather lower silica and nephelinitic affinities, the approximately equal 



