404 THE GEOLOGY OF THE NEW HEBRIDES, 



either in single file as is the case in the south, or two and three 

 abreast as in the north (see appended map, Plate xxvii.) The 

 larger islands are high (highest point 5520 ft.), and show extensive 

 exposures of volcanic rocks underlying areas of raised coral 

 ■terraces, which latter reach in some cases an elevation of quite 

 2000 ft. The smaller islands are often wholly volcanic; in others 

 raised coral reef-material predominates, and may even completely 

 hide from view the more solid rocks below. 



The Banks Islands, which are really a northerly extension of 

 the eastern arm of the New Hebrides, are almost solely volcanic 

 in origin, reef debris taking relatively only a very small share in 

 their formation; as a result they are high and rugged. Vanua 

 Lava and Gaua are the largest islands, with areas each about 85 

 «q.miles; ten other smaller islands complete the group and bring 

 the total area up to about 193 sq. miles. 



Further to the north-west lies the Torres Group of six small 

 islands with a total area of only about 30 sq. miles. They are 

 composed wholly of raised coral with underlying detrital founda- 

 tion beds, and rise up in terrace-formation to a maximum height 

 of 1230 ft. 



The prevailing wind is a south-easterly trade, though light 

 north- westerlies are not uncommon at certain seasons of the year. 

 Hurricanes are to be expected any time between the latter end 

 of November and the end of February, and are often accountable 

 for much destruction of property. 



There are several active volcanoes in the Group, and it is to 

 such agencies that the whole land-surface probably owes its 

 origin. Earthquakes are of frequent occurrence, and are some- 

 times alarmingly severe ; these have occasionally been followed 

 b)y tidal waves. 



Part I.— Sec.1. SYSTEMATIC GEOLOGY. 



This section deals with each of the islands separately, and 

 contains all available accurate geological information relating 

 thereto. The limited time at our disposal necessitated very short 

 calls at the various islands excepting Efat^ and Santo; indeed, 



