

Parr I. Secr. i. § 3.] SUBMARINE VOLCANOES. 251 
_ the sea are for the most part inaccessible. Here and there, as among 
- the islands of the Greek Archipelago and at Tahiti, elevation of the 
sea-bed has taken place, and brought to the surface beds of lava 
which had been erupted and had consolidated under water. It 
will be seen from the accompanying chart (Fig. 58), that the islands 
of Santorin and Therasia form the unsubmerged portions of a great 
crater-rim rising round a crater which descends 1278 feet below sea- 
level. The materials of these islands consist of a nucleus of marbles 
and schists nearly buried under a pile of tuffs (trass), scorie and 
i BS 

Fig. 58.—Map OF PARTIALLY-SUBMERGED VOLCANO OF SANTORIN. 
a, Thera, or Santorin ; b, Therasia; c, Mikro Kaimeni; d, Neo Kaimeni. The figures 
denote soundings in fathoms, the dotted line marks the 100 fathoms line, 
sheets of lava, the bedded character of which is well shown in the 
accompanying sketch by Admiral Spratt (Fig. 59), who with the late 
Professor Edward Forbes examined the geology of this interesting 
district in 1841. They found some of the tuffs to contain marine 
shells and thus to bear witness to an elevation of the sea-floor since 
- voleanic action began. More recently the islands have been carefully 
studied by various observers. K. von Fritsch has found recent 
marine shells in many places up to heights of nearly 600 feet above 
the sea. The strata containing these remains he estimates to be at 
least 100 to 120 métres thick, and he remarks that in every case he 
found them to consist essentially of volcanic débris and to rest upon 
_ voleanic rocks. It is evident therefore that these shell-bearing tuffs 
were originally deposited on the sea-floor after volcanic action had 
begun here, and that during later times they were upraised, together 
with the submarine lavas associated with them.'| Fouqué concludes 
1 See Fritsch, Z. Deutsch. Geol. Ges. xxiii. (1871) pp. 125-213. The most complete 
and elaborate work is Fouqué’s monograph (already cited), “ Santorin et ses Eruptions,’’ 
Paris, 4to, 1880, where copious analyses of rocks, minerals, and gaseous emanations, with 
_ maps and numerous admirable views and sections, are given. In this volume a biblio- 
graphy of the locality will be found. 
