388 T. Mellard Reade—Oceans and Continents. 
going on between the great oceans and great continents, by which 
first one is up, and the other down. Any one who holds such views 
must be strangely ignorant of physical geology. 
The flatness of the ocean-floor is another argument urged against 
its ever having been land. I think, however, that those who use it 
would hardly realize what Europe or any other continent would 
look like if its configuration were traced only by soundings taken in, 
say, 3000 fathoms of water! Very probably the same argument 
would be used to prove that it had never been a continent. 
In the mid-Atlantic, in what is called the Challenger Ridge, and 
its extensions, there are certain volcanic peaks, such as the Azores, 
St. Paul’s Rocks, Ascension, Tristan da Cunha, ete. I ask, if these 
peaks had 1000 fathoms of water over them, should we know of 
their existence? Their position as they are now seen above the 
surface could only be ascertained and recorded by good navigators. 
What then would happen were they out of the range of vision with 
a deep ocean rolling over them? In all probability on the same ridge 
there exist submerged peaks of which we know nothing.’ The great 
depths of the ocean are also urged as an argument against it ever 
having been the site of land; and when it is shown that the highest 
mountains measure vertically the greatest depths of the seas, it is, 
per contra, pointed out that these are only isolated peaks, while the 
ocean depths extend over thousands of square miles. But it has 
been shown by Professor Judd, F.R.S.,? that the strata of the 
Alps measure fully five miles in vertical thickness, and that the sea- 
floor must have subsided to that extent at least to allow of their 
deposition. Dana had previously shown this to be true of the 
Appalachians, and I have no doubt most high mountain ranges will 
tell a somewhat similar story. The Gulf of Mexico is over 2000 
fathoms in its deepest part, yet there is just reason to suppose 
that it once formed part of the continent of South America.® In 
a paper “On the Caribbean Sea,” Nature, July 15, 1880, p. 242, 
further soundings of the steamer “‘ Blake”’ are described; one of the 
features discovered being “‘an extraordinary submarine valley,” ‘in 
length 700 statute miles, from between Jamaica and Cuba, nearly to 
the head of the Bay of Honduras, with an average breadth of 80 
miles.” 
Professor Geikie, in the paper quoted, also points out that Britain 
must have subsided at least three miles during the Silurian period, 
though he assumes deposition to have kept pace with subsidence, as 
indeed does Prof. Jydd in the case of the Alps. To come to more 
recent times, in the Glacial period Great Britain subsided to the 
‘ Mr. Murray says, in the paper before alluded to, on Coral Reefs, etc. (p. 507) :— 
“* The soundings of the ‘‘Tuscorora’’ and ‘‘Challenger’’ have made known numerous 
submarine elevations ; mountains rising from the general level of the ocean’s bed, 
at y Uepth of 2500 or 3000 fathoms, up to within a few hundred fathoms of the 
surface. 
* Contributions to the Study of Volcanos, Gron. Mac. Dec. II. Vol. III. 1876. 
° Dredging of the U. S. Steamer ‘‘Blake,’’ 1879, Letter No. 3, pp. 299-801. 
Alex. Agassiz speculates on the former connexion of the West India Islands with the 
continent of South America. : 
