THE DECCAN TRAPS 775 



It seems scarcely necessary to give the norms of all the analyses ; so that 



those of only four, the two extremes of the less silicic types and two of 



the more silicic, are given in Table II, with the norm of the average 



composition. 



Table II 



Norms of Deccan Traps 



12 3 4 5 



Quartz 5.46 2.40 4.38 4.14 



Orthoclase 3.34 5.56 6.67 7.78 4.45 



Albite 25.15 18.34 25.68 28.82 22.01 



Anorthite 23.35 21.13 24.46 20.29 23.07 



Diopside 18.40 19.55 13.98 10.74 17.41 



Hypersthene 13.68 15.53 21.16 18.58 17.78 



Olivine 7.49 



Magnetite 3.25 6.50 1.86 4.87 4.64 



Ilmenite 1.67 5.93 0.91 1.22 3.65 



Apatite 0.67 0.67 1.68 1.51 1.01 



1. Kolhapur. 111.5.3(4) . (4)5. 



2. Nasik. 111.(4)5.(3)4.4. 



3. Rajmahal Hills. ( II ) III . 5 . 3" . 4. 



4. Bombay. (II) III. "5. 3. 4. 



5. Average of 11. III. "5. 3(4) .4". 



These norms show some rather interesting features. That of the Kol- 

 hapur basalt (number 1) is the only one in which quartz does not occur 

 and in which olivine is a femic constituent. A notable amount of quartz 

 occurs in the norm of even the olivine-bearing Nasik basalt (number 2). 

 The amounts of albite and anorthite are about equal to each other in all 

 the norms, this being well seen in the average, the albite increasing in 

 the more silicic rocks, as does the orthoclase. The molecules of diopside 

 and hypersthene are also in general present in about equal amount, as the 

 average norm shows, but that of diopside is somewhat in excess in the 

 less silicic group, and that of hypersthene in the more silicic. The very 

 considerable amount of normative hypersthene is in harmony with the 

 observation that the pyroxene is an enstatite-augite, as determined by 

 Merwin. 



The Oregonian Region 



In the extreme northwestern corner of the United States — in southern 

 Idaho, northern Oregon, and southern Washington — there is an extensive 

 area covered by thick horizontal flows of basalt. These are commonly 

 known as the Columbia River and Snake River basalts, from the valleys 

 which they chiefly occupy. The term "Oregonian" is applied here to this 



