540 THE DISTRIBUTION, ETC., OF ALKALINE ROCKS, 



8. Other Areas. — In addition to the alkaline areas mentioned 

 there are numerous other areas where alkaline rocks occur. A 

 brief summary will be given. 



(a) The nepheline syenites of the province of Miask, Ural 

 Mountains, occupying a position relative to the great Russian 

 plain similar to that occupied by the Kola and Transylvanian 

 areas.* 



^b) The soda-micro-granite of Rockall Island, west of Ireland. 

 This is probably Post-Triassicf 



(c) The soda-trachytes of Ischial (Scarraputa, Ischia). These 

 rocks are remarkably like our Australian segirine trachytes. The 

 island of Ischia is situated on the border of the Ionian senkungs- 

 feld. Age: Tertiary. 



(d) Soda-trachytes, pantellarites, comendites, and leucite basalts 

 occur abundantly in the Naples volcanic area, which is situated 

 on the border of the Tyrrhenian senkungsfeld. Age: Tertiary to 

 Recent.§ 



(e) Phonolites and trachytes with nosean and leucite from the 

 Laacher See. Tertiary. [| 



(f) Nepheline phonolites of the Haute Noire. Tertiary. 



(g) Soda-trachytes of the Auvergne Mountains. Tertiary; 

 superimposed on the massive of Central France. 



(h) Soda-trachyte of Kelberg, Eifel; overlying Devonian rocks. 



Lava Tertiary (same as (e,) Laacher See). 



(i) Soda-rhyolites of Hekla, Iceland, of pre-glacial age.^f 



( j) Microgranite with riebeckite, Ailsa Craig;** the microscopic 



character of this rock corresponds to that of some of my Glass 



* L. V. Pirsson, Amer. Journ. of Sci. Vol. ix. 1900. 

 t Geol. Mag. N. S. Decade iv. Vol. vi. Apr. 1899. 

 % G. von Rath, Zeitschr. f. d. deutsch. Geol. Gesel. B.18, 1866; and H. S. 

 Washington, Amer. Journ. of Sci. Vol. i. May, 1896. 



§ Washington, ' The Roman Comagmatic Region '; and ' Some Analyses 

 of Italian Volcanic Rocks.' Amer. Journ. of Sci. Vols. viii. and ix. 

 I! Hubbard, Tscher. Min. Mitth. Bd. viii. Heft 5. 

 H Beitr. z. Kentn. der islandschen Liparit, by H. Backstrom; Abstract in 

 Min. Mag. x. 



** J. H. Teall, Min. Mag. Vol. ix. p.219. 



