275 & Powers — Volcanic Domes in the Pacific. 



Summary. 



The following table shows the size, composition, and impor- 

 tant features connected with the various volcanic domes of the 

 world. Through lack of sufficient data, the following domes 

 are omitted : those of the Auvergne region of France, including 

 Puy Chopine, Puy de Dome, and Puy Sarcouy, 10 those in 

 Italy, including Monte Tolfa, Monte Cerveteri, 17 Monte Santa 

 Croce, Monte Lattani, 18 and Monte Venere 10 ; that on Saba 20 ; 

 the dome of Chokai-san and the questionable spin© of Sam- 

 bondake discussed above; and those which may exist on the 

 Lipari Islands, 21 Pantclleria, 22 or on Sardinia. 23 The lateral 

 cone of the Vesuvius formed in 1895-9 grew exotically accord- 

 ing to Dr. H. S. Washington, and does not represent a dome. 24 

 Certain volcanoes of Ecuador which have been described by 

 A. Stiibcl, 25 as having no summit crater, appear to have suf- 

 fered from glacial and other forms of erosion, and in two 

 instances the rock at the summit is described as an agglomerate. 



In attempting to draw any general conclusions about vol- 

 canic domes it is seen that very little is known concerning 

 many of the examples cited. All of the volcanoes on which 

 domes have appeared must be classed as old and 13 of the 25 

 are extinct. In at least 7 of the 13 extinct volcanoes, activity 

 appears to have been closed by the formation of the dome or 

 spine over the vent. Not all volcanoes, however, become extinct 

 with the formation of domes, for Usu has been occasionally 

 active during the Christian era, and a few minor eruptions 

 have been recorded in the now quiescent or extinct Kaimondake. 



Tarumai and Mont Pelee have furnished information con- 

 cerning the mechanism of dome-formation. The eruption 

 commences with earthquakes and explosions as the gas from the 



"Michel Levy, Eighth Int. Geol. Cong., Paris, 1000, Guide Book 14, 

 pp. 7-12; P. Glangeaud, Les volcans d' Auvergne, Paris, 1910; A. Lacroix, 

 La montagne Pelfie apres ses eruptions, Paris, 1908; M. Boule, La 

 Geographie, vol. xi, pp. 7-20. 1905. 



17 H. S. Washington, Italian penological sketches, Jour. Geol., vol. v, 

 p. 350, 1897. 



"Idem, pp. 241-4. 



19 Idem, vol. iv, pp. 828-30, 189G. 



20 E. O. Hovey, Volcanoes of Martinique, Guadeloupe, and Saba, Eighth 

 Int. Geogr. Congr., Washington, pp. 447-51, 1904; K. Sapper, In den 

 Vulcangebieten Mittelamerikas und Westindiens, Stuttgart, p. 219, 1905. 



21 A. Bergeat, Staukuppen, Festband Neues Jahrb, 1907. 



22 Idem; also H. S. Washington, Volcanoes and rocks of Pantelleria, 

 Jour. Geol., vol. xxi, pp. 662, 1913. 



23 H. S. Washington, Some lavas of Monte Arci, Sardinia, this Journal, 

 vol. xxxvi, pp. 577-90, 1913. 



21 Personal communication from Dr. H. S. Washington. 



2S Die Vulkanberge von Ecuador, Berlin, 1897, especially pp. 28, 405, 418. 



