BY D. MAWSON. 419 



examined, the meagre development of recent raised reefs, and 

 tiieir complete absence at elevations exceeding 150 ft. This is 

 more to be wondered at when it is remembered that it lies 

 midway between Efate and Santo, both regions of extensive 

 recent upheaval. 



Referring to the Admiralty chart it will be noticed that 

 elevated plateaux and white cliffs are a dominant feature of the 

 north-west coast; these cliffs may possibly be composed of 

 Miocene limestones, but the contour strongly suggests a more 

 recent age. If this latter be the case, then the non-appearance 

 of recent coral at similar elevations on the parts of the coast 

 examined may be due to proximity to the volcano of Ambryra.* 



The land appears to be built up, for the most part, of a great 

 thickness of Miocene submarine tuffs and foraminiferous lime- 

 stones, intruded by andesite sills and dykes, 



In all probability dry land has existed since Miocene or early 

 Pliocene times; and although little subsequent elevation is 

 evidenced, yet, situated as it is, in the midst of abundant 

 proof of extensive recent upheaval, there can be little doubt but 

 that it has weathered out a succession of oscillations resulting 

 finally in a slight positive movement. 



1. A decomposed fine-grained basic ash derived, no doubt, 

 from the volcano of Ambrym, which is situated only 38 miles to 

 windward. Small fragments of decomposed pyroxene appear in 

 a very fine-grained yellowish dust-like base, which when dried is 

 light and very absorbent. This rock is found also underlying 

 a scanty coral capping and composing the main body of the small 

 islands of Rano and Atchin ; in all probability obtains an 

 extensive development on this coast of Malekula. 



2. Black sand is a marked feature of the sea-shores throughout 

 a large part of the Group, and in such neighbourhoods is also 

 found to a less extent in the river-beds. 



* Referable to two causes — First, an inward dip towards the volcano of 

 Ambrym is to be expected and might be sufficient to account for a much 

 greater elevation on the west than on the east coast of Malekula. A second 

 explanation, though much more limited in application, might be found in 

 Lieut. Frederick's observation that coral polyps do not live near the active 

 volcanic islands, e.g.^ Tongoa. 



