78 DE. H. S. WASHINGTON ON THE TITANIFEEOT/S [Feb. I907, 



the dosalane class, thus clearly indicating by their systematic names 

 their great content in silica and alumina, and their lesser content in 

 the femic constituents, such as iron-oxides, magnesia, and titanium- 

 dioxide. 1 These Sardinian basalts, furthermore, are almost the only 

 basalts that ^show in the norm high hypersthene (which enters into 

 modal augite), and little or no olivine, and the comparative rarity 

 of this last mineral among them has been noted above. 



Again, the basalts of Catalonia, which are almost the only basalts 

 with recognizable nephelite under the microscope, are similarly the 

 only ones to fall in order 6, with notable amounts of this mineral 

 in the norm. Finally, it was pointed out on a previous page that 

 in this series lime is not very high, that is, for such basaltic rocks ; 

 and this feature is revealed in the magmatic position of these types 

 in alkalicalcic rangs, or even in domalkalic ones : whereas, as 

 has been pointed out elsewhere, 2 the majority of ' basalts ' fall in 

 docalcic rangs, such as hessase or auvergnase. 



It should be borne in mind that the new names used here 

 express only the magmatic (chemical) characters of the rocks. The 

 mineral and textural features are to be expressed according to the 

 proposed system by qualifying compound adjectives, or eventually 

 by typal adjectives. But further discussion of these and cognate 

 topics is uncalled for here. 



Y. Extent of the Region. 



The real extent of this zone or region of chemically and mineralo- 

 gically similar rocks is as yet problematical, and its full discussion 

 must be reserved for the future. The possible richness of the Etna 

 basalts in titanium, and their connexion with those of Pantelleria, 

 has been suggested by Dr. Fcerstner in au article cited above. But 

 no complete and trustworthy analyses of these lavas are available, 

 those of Sartorius von Waltershausen, Jewett, Silvestri, and 

 Bicciardi being manifestly at fault as regards either accuracy or 

 completeness, or both combined. In their figures for silica, the 

 oxides of iron, lime, and the alkalies, the Etna lavas are much 

 like the Pantellerian basalts ; and the high figures for alumina 

 commonly reported maybe due, in part to admixture with magnesia 

 (which is commonly low), and in part to the non-separation of 

 titanium-dioxide, which would be precipitated and weighed with it. 



Along the southern coast of France are several ' basaltic ' volcanoes, 

 as at Montpellier and Agde, and it is possible that these may 

 eventually turn out to be connecting links between those of Sardinia 

 and Catalonia, but their chemical characters are quite unknown to 

 me. A volcanic zone, in "which ' basalts ' occur, extends south from 

 Catalonia along the eastern coast of Spain, including the Columbretes 



1 Exceptions to this rule are apparently presented by Nos. 5 & 6, but No. 5 

 (with less silica than the others) is near the dosalic border of salfemane, while 

 in No. 6 the higher magnesia and lime (as compared with those of Nos. 7 & 8) 

 serve to throw the rock into the salfemane class (camptonose), despite its 

 high silica. 



2 H. S. Washington, U.S. Geol. Surv. Prof. Paper No. 14 (1903) p. 75. 



