SKETCH OF &GINA AND METHANA. 157 
well as at the volcanic centers situated on the same fracture 
line. 
If we adopt Iddings’ view it would seem, as the same writer 
has suggested in the case of the South American volcanoes, that 
the volcanoes of the A‘gina-Methana region are comparatively 
young and have not completed their full course of differentiation. 
Whether this course will eventually be completed, or whether for 
some unknown reason they have ceased activity forever, and 
will never reach the basalt and rhyolite stage it is impossible to 
say, though the latter is decidedly the more probable, as has 
been mentioned above. 
But it must be remarked (as was pointed out by von Buch 
many years ago”) that basalt is entirely lacking along the whole 
. volcanic line from Nisyros to Kolantziki3 On the other hand, 
rhyolite is said to occur on the islands of Kos# and Milos,> though 
in the case of the latter, owing to imperfect description and lack 
of analyses, its occurrence is somewhat doubtful. In these two 
cases the volcanoes are most certainly extinct, but no indication 
is given as to the relative age of the rhyolite as compared with 
the andesites which compose the other eruptive masses of the 
two islands. The volcano of Santorini is not yet extinct,° and 
here, to judge from the not very numerous good published 
analyses (which, moreover, do not cover the various varieties 
completely) it seems probable that the order of eruptions has 
followed the same law as in our district, the earliest rocks (those 
of Balos and Megalo Vouno and Thera) having been either 
tJourR. OF GEOL., L., p. 169. 
2vy. BucH: Phys. Besch. d. Canar. Inseln. Berlin, 1825, p. 359. 
3Basalt occurs to the north at Samothrace (NIEDZWIEDZKI: Min. Pet. Mitth., 
1872, p. 107) and near Persufli in Thessaly (LEPsius: Geol. v. Attica, Berlin, 1893, p. 
169), which we may suppose to be on a westward continuation of the Asia Minor line 
running from Armenia through Afium Kara Hissar and the Katakekaumene to the 
Troad and Lemnos, along which we know basalt to occur. 
4DoELTER: Verh. Geol. Reichsanstalts, 1875, p. 233. 
5S EHRENBURG: D. Inselgruppe v. Milos, Leipzig, 1889, p. 102. RoTu: Geol. IL., 
Pp- 229. 
6 The crater of Giorgio Kaimeni was in a solfataric state when I visited it in the 
spring of 1893. 
