306 Hutt—On the Geological Age of the North Atlantic Ocean. 
distribution of animals and plants, either in geological or comparatively recent 
times; nor in consequence of new observations on the relations of stratified rocks 
in various parts of the globe;* for unquestionably, as it seems to me, the facts 
recently brought to light tend rather to disprove than to confirm these views. 
Dr. Wallace’s great work on ‘‘The Geographical Distribution of Animals,” Pro- 
fessor Haeckel’s ‘‘Schépfungeschichte,’ and Darwin’s work on Coral Reefs, all 
bristle with facts illustrating the changes in the distribution of animal and plant 
life, in consequence of the changes in position of land and sea. Lyell, however, 
was perfectly familiar with all the facts and arguments bearing on this great 
problem ; and we may well pause before we accept views, from whatever quarter 
propounded, which appear to run counter to those unfolded, or amplified, by so able 
an exponent of the principles of geological science.t 
The problem now under consideration has generally been treated on dynamical 
or purely physical grounds; but anyone who considers the amount of controversy 
to which this mode of treatment has given rise, and the opposite conclusions arrived 
at from the consideration of somewhat similar physical facts, will probably come 
to the conclusion, either that the problem itself does not admit of solution by this 
mode of treatment, or that we must wait till physicists are more in accord amongst 
themselves before we can accept their conclusions. I propose to treat the ques- 
tion of the geological age of one section of the aqueous envelope, namely, the 
North Atlantic, chiefly on stratigraphical grounds; and to point out how, ulti- 
mately, by the extension of our knowledge of the geological structure of the 
continents, we may hope to arrive at conclusions more or less definite regarding 
the geological age of other adjoining oceans. 
In dealing with this problem I shall endeavour to ascertain how the characters 
and distribution of the strata of the lands bordering the Atlantic lend their aid 
iowards its solution. 
E. 
(a) The Formations of chief import in the Problem.—As prime factors in this prob- 
lem, there are three great groups of strata of which we may make use, namely, the 
Archeean, the Silurian, and the Carboniferous: the intermediate groups—namely, 
the Cambrian and Devonian—being restricted in area, and more or less local, need 
not in this inquiry be considered. 
* The discovery recently made by the Danish Expedition, that the Island of South Georgia is made 
of slate rock, is one of great importance as bearing on this question. This island is a thousand 
geographical miles from any continental land, and rises from deep water. The significance of its 
position as bearing on this question has been ably pointed out by Mr. Mellard Reade in the ‘‘ Geological 
Magazine,” and in “ Nature.” 
+ When we find the table-land of Thibet—at an elevation of 20,000 feet—formed (as Mr. Blanford, 
F. R.S., has shown) largely of Cretaceous beds once deposited below the waters of the ocean, we have 
an illustration of the extent of the changes the earth’s surface has undergone even in Tertiary times. 
