474 Notices of Memoirs — Prof. LapioortWs Address. 



on which are strung the Festoon Islands of Western Asia ; — the band of Mount 

 St. Elias, the Aleutians, Kamtchatka, and the Kuriles ;^the band of F'usijama, 

 Krakatoa, and Sangir. The rate of movement of the earth's surface doubtless 

 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 phenomena on the face of our globe. 



We find, precisely as we anticipated, that the wave-like surface of the earth of 

 the present day reflects in its entirety the wave-like arrangement of the geological 

 formations below. On the land we find that the surface arches and troughs answer 

 precisely to the grander regional anticlines and synclines of the subterranean 

 sedimentary sequence ; and it may, I believe, be regarded as certain that the 

 submarine undulations have a similar or complementary relationship. We find in 

 the New Geology, as Hutton found in the Old, that geography and geology are 

 one. We find, as we suspected, that the physiognomy ot the face of our globe 

 is an unerring ind^x of the solid personality beneath. It bears in its lineaments 

 the characteristic family features and the common traits of its long line of geological 

 ancestors. 



Such, it seems to me, is an imperfect account of the introductory paragraphs of 

 that great chapter in the New Geology now in course of interpretation by geologists 

 of the present day ; and we have translated them exactly in the old way by the aid 

 of the only living geological language, namely, the language of present natural 

 phenomena, and I doubt not that sooner or later the rest of this great chapter 

 will be read by the same simple means. 



I have strictly confined myself to-day to the discussion of the characteristics 

 of the simple geological fold as reduced to its most elementaiy terms of arch, 

 trough, and unbroken septum ; for this being clearly understood, the rest naturally 

 follows. But this twisted plate is really the key which opens the entire treasure- 

 house of the A'i?7«/ Geology, in which lie spread around in bewildering confusion 

 facts, problems, and conclusions enough to keep the young geologist and other 

 scientific men busily at work for many a long year to come. 



Into this treasure-house I often wander myself, in the few leisure hours that 

 I can steal from a very busy professional life ; and out of it I bring now 

 and again heresies that sometimes amuse and sometimes horrify my geological 

 friends. As you have so patiently listened to what I have already said, perhaps 

 you will permit me in a few final sentences to indicate in brief some of those 

 novelties which I see already more or less clearly, and a few of those less novel 

 points on which it appears to me that more light is wanted. My excuse is twofold, 

 first, to furnish material for work and controversy to the young geologists ; and 

 second, to obtain aid for myself from workers in other walks of science. 



The account of the simple rock-fold which I have already given you is of 

 the most elementary kind. It presupposes merely the yielding to tangential 

 pressure from front and back, combined with effectual resistance to sliding. 

 But in the layers of the earth-crust there is always in addition a set of 

 tangential pressures theoretically at right angles to this. The simple fold 

 becomes a Jolded fold, and the compound septum twists not only vertically but 

 laterally. On the surface of the globe the double set of longitudinal and 

 transverse waves brought about in this way is everywhere apparent. They 

 account for the detailed disposition of our lands and our waters, for our 

 present coastal forms, for the direction, length, and disposition of our mountain- 

 ranges, our seas, our plains, and lakes. The compound arch becomes a dome, 

 its complementary trough becomes a basin. The elevations and depressions, 

 major and minor, are usually twinned, like the twins of the mineralogist, the 

 complementary parts being often inverted, and turned through 180" (compare 

 Italy with the Po-Adriatic depression). Every upward swirl and eddy has its 

 answering downward swirl. The whole surface of our globe is thus broken 

 up into fairly continuous and paired masses, divided from each other by moving 

 areas and lines of mountain making and crust movement, so that the surface of the 

 earth of the present day seems to stand midway in its structure and appearance 

 between the surfaces of the sun and the moon, its eddies wanting the mobility of 



