British Association, Edinhurgli Meeting — Lapworth. 239 
of a great circle, we find that we have before us a crust fold of the very- 
grandest order. We have one mighty continental arch stretching from 
Japan to Chile, broken submedially by the sag of the Atlantic trough; 
and this great terrestrial arch stands directly opposed to its natural com- 
plement, the great trough of the Pacific, which is bent up in the middle 
by the mightiest of all the submarine buckles of the earth-crust, on 
which stand the oceanic islands of the central Pacific. 
But if this be true, then the septum of all septa on our present earth- 
crust must cross our grandest earth fold where the very steepest gradi- 
ent occurs along this line, and it must constitute the centre-point of the 
moving earth fold, and of greatest present volcanic activity. And where 
is this most sudden of all depressions? Taught once more by our geo- 
logical fold, the answer is instantaneous and incontrovertible. It is on 
the shores of .Japan, the region of the mightiest and most active of all 
the living and moving volcanic localities on the face of our globe. 
But the course of the line which we indicated as forming our grandest 
terrestrial fold returns upon itself. It is an endless fold, an endless 
band, the common possession of two sciences. It is geological in origin, 
geographical in effect. It is the wedding-ring of geology and geography, 
uniting them at once and for ever in indissoluble union. 
Such an endless fold, again, must have an endless septum, which, in 
the nature of things, must cross it twice. Need I point out to the merest 
tyro in these wedded sciences that if we unite the Old and New Worlds 
and Australia, with their intermediate sags of the Antarctic and Indian 
oceans, as one imperial earth arch, and regard the unbroken watery ex- 
panse of the Pacific as its complementary depression, then the circular 
coastal band of contrary surface fiexure between them should constitute 
the moving master septum of the earth crust. This is the "Volcanic 
girdle of the Pacific," our "Terrestrial Ring of Fire." 
Or, finally, if we rather regard the compact arch of the Old World 
itself as the natural complement of the broken Indo-Pacific depression, 
then the most active and continuous septal band of the present day should 
divide them. Again our law asserts itself triumphantly. It is the great 
volcanic and earthquake band on which are strung the Festoon islands 
of western Asia, the band of mount St. Elias, the Aleutians, Kamtchatka, 
the Kuriles, the band of Fusijama, Krakatoa, and Sangir. The rate of 
movement of the earth's surface doubtl ss everywhere varies directly as 
the gradient. 
We find, therefore, that even if we restrict our observations to the most 
simple and elementary conception of the rock fold as being made up of 
arch-limb, trough-limb, and twisting but still continuous septum, we are 
able to connect, in one unbroken chain, the minutest wrinkle of the finest 
lamina of a geological formation with the grandest geographical phe- 
nomena on the face of our globe. 
We find, precisely as we anticipated, that the wave-like surface of the 
earth of the present day refiects in its entirety the wave-like arrange- 
ment of the geological formations below. On the land we find that the 
surface arches and troughs answer precisely to the grander regional an- 
