98 
ISLAND LIFE. 
[part I. 
continents nor continental islands existed where our oceans 
now extend ; for had they existed, Palaeozoic and Secondary 
formations would in all probability have been accumulated 
from sediment derived from their wear and tear ; and these 
would have been at least partially upheaved by the oscillations 
of level, which must have intervened during these enormously 
long periods. If then we may infer anything from these facts, 
we may infer that, where our oceans now extend, oceans have 
extended from the remotest period of which we have any 
record ; and, on the other hand, that where continents now 
exist, large tracts of land have existed, subjected no doubt to 
great oscillations of level, since the Cambrian period.” This 
argument standing by itself has not received the attention it 
deserves, but coming in support of the long series of facts of 
an altogether distinct nature, going to show the permanence of 
continents, the cumulative effect of the whole must, I think, 
be admitted to be irresistible . 1 
1 Of late it has been the custom to quote the so-called “ ridge” down 
the centre of the Atlantic as indicating an extensive ancient land. Even 
Professor Judd adopts this view, for he speaks of the great belt of Tertiary 
volcanoes “ which extended through Greenland, Iceland, the Faroe Islands, 
the Hebrides, Ireland, Central France, the Iberian Peninsula, the Azores, 
Madeira, Canaries, Cape de Verde Islands, Ascension, St. Helena, and 
Tristan d'Acunha, and which constituted as shown by the recent soundings 
of H.M S. Challenger a mountain-range, comparable in its extent, elevation, 
and volcanic character with the Andes of South America” ( Geological 
Mag. 1874, p. 71). On examining the diagram o£ the Atlantic Ocean in 
the Challenger Reports , No. 7, a considerable part of this j-idge is found 
to be more than 1,900 fathoms deep, while the portion called the “Connecting 
Ridge ” seems to be due in part to the deposits carried out by the River 
Amazon. In the neighbourhood of the Azores, St. Paul’s Rocks, Ascension, 
and Tristan d’Acunha are considerable areas varying from 1,200 to 1,500 
fathoms deep, while the rest of the ridge is usually 1,800 or 1,900 fathoms. 
The shallower water is no doubt due to volcanic upheaval and the accumu- 
lation of volcanic ejections, and there may be many other deeply submerged 
old volcanoes on the ridge ; but that it ever formed a chain of mountains 
“comparable in elevation with the Andes,” there seems not a particle of 
evidence to prove. It is however probable that this ridge indicates the 
former existence of some considerable Atlantic islands, which will serve 
to explain the presence of a few identical genera, and even species of 
plants and insects in Africa and South America, while the main body 
of the fauna and flora of these two continents remains radically distinct. 
