372 COSMOS. 



ed by beautiful glistening leucite and sanidine sand, as well 

 as by mounds of pumice, is nearly 24 geographical miles long, 

 and lies in the centre of the north island of New Zealand, at 

 an elevation, -according to Dieffenbach, of 1337 feet above 

 the surface of the sea. The ground for two English square 

 miles round is entirely covered with solfataras, vapor holes, 

 and thermal springs, the latter of which form, as at the Gey- 

 ser, in Iceland, a variety of silicious precipitates. (*) West- 

 ward of Tongariro,* the chief seat of volcanic action, whose 

 crater still ejects vapors and pumice-stone ashes, and at a dis- 

 tance of only sixteen miles from the western shore, rises the 

 volcano of Taranaki (Mount Egmont), 8838 feet high, which 

 was first ascended and measured by Dr. Ernst Dieffenbach in 

 November, 1840. The summit of the cone, which in its out- 

 line more resembles Tolima than Cotopaxi, terminates in a 

 plain, out of which rises a steep ash-cone. No traces of pres- 

 ent activity, such as are seen on the volcano of the White 

 Island* and on Tongariro,* are visible, nor any connected 

 stream of lava. The substance composed of veiy thin scales, 

 and having a ringing sound, which is seen projecting with 

 sharp points like fish-bones, from among the scoriae, in the 

 same manner as on one side of the Peak of TenerifTe, resem- 

 bles porphyritic schist, or clink-stone. 



A narrow, long-extended, uninterrupted accumulation of 

 island groups, erupted from northwestern fissures, such as 

 New Caledonia and New Guinea, the New Hebrides and 

 Solomon's Island, Pitcairn, Tahiti, and the Paumotu Islands, 

 traverses the great Ocean in the Southern hemisphere in a 

 direction from west to east, for a length of 5400 geograph- 

 ical miles, between the parallels of latitude of 12 and 27, 

 from the meridian of the east coast of Australia as far as 

 Easter Island, and the rock of Sala y Gomez. The western 

 portions of this crowd of islands (New Britain,* the New 

 Hebrides,* Vanikoro* in the Archipelago of Santa Cruz, and 

 the Tonga group*) exhibit at the present time, in the middle 

 of the nineteenth century, inflammation and igneous action. 

 New Caledonia, though surrounded by basaltic and other 

 volcanic islands, has nevertheless nothing but Plutonic rock,f 

 as is the case with Santa MariaJ in the Azores, according to 



(*) Dana, p. 445-448 ; Dieffenbach, vol. i., p. 331, 339-341 and 397. 

 On Mount Egmont, see vol i., p. 131-157. 



t Danvin, Volcanic Islands, p. 125 ; Dana, p. 140. 



j L. de Buch, Descr. des 7. Can., p. 365. On the three islands here 

 named, however, phonolite and basaltic rock are also found along >vith 



