472 THE GEOLOGY OF THE NEW HEBRIDES, 



extinct. The limestone forming the series of more recent raised 

 reefs is considerably newer in ajjpearance, and so is probably to 

 be relegated to a very recent epoch. 



The elevatory movements evidenced in these raised reefs is of 

 a see-saw type, greatest in the west, and least (probably in many 

 cases a minus quantity) in the east, where the great recent basic 

 eruptions have taken place. As these eruptions were contem- 

 poraneous with the upheaval it might be argued that they were 

 the prime cause of the disturbance; this, however, can hardly be 

 the case, as the tilt is down towards the centres of eruption, 

 where it is usually negative. 



The proportionate increase in relative heights of the terraces 

 in an east to w^est traverse is proof that the upheavals were not 

 primarily horizontal, and the present easterly dip produced later 

 by the development of a sag in towards the volcanic centres. 



From these facts it seems most reasonable to relate the 

 elevatory tendency to a continuance"^ of the tectonic movements 

 so critically developed in Miocene times, and to regard the 

 volcanic eruptions as a direct outcome of the folding and 

 consequent on it. It is, however, still maintained that minor 

 elevations may have been directly due to the volcanoes, as 

 evidenced by the fairly numerous intrusions of andesite into the 

 Miocene series. 



If at any time the New Hebrides ridge formed continuous 

 land connected in the north or elsewhere wdth other land-masses, 

 these conditions are most likely to have prevailed in its early 

 history. Geological evidence, so far as ascertained, is in this 

 respect uncertain, but that such must have been the case has 

 been conclusively proved on biological grounds by evidence 

 brought forward by Mr. C. Hedley.f 



* The Himalayas afford a classical example of continuance of folding, 

 beginning in the Eocene and extending down to recent times. Vide Suess,, 

 ' The face of the Earth.' 



f **A Zoogeographic Scheme for the Mid-Pacific." Proc. Linn. Soc. 

 N. S. Wales, xxiv. 391, 1899. 



