36 



ranges, our seas, our plains, and lakes/' The stresses *" account 

 also for the formation of laccolites, of granite cores, and of petro- 

 logical provinces ; and they enable us also to understand many of 

 the more striking phenomena of metamorphism." f" The surface 

 of the earth of the present day seems to stand midway in its 

 structure and appearance between that of the sun and that of the 

 moon, its eddies wanting the mobility of those of the one and the 

 symmetry of those of the other/' 



I" Thus from the microscopic septa of the laminae of the 

 geological formations we pass outwards in fact to those moving 

 septa of our globe, marked on the land by our new mountain- 

 chains, and on our shores by our active volcanoes. Thence we 

 sweep, in imagination, to the fiery eddies of the sun, and thence to 

 the glowing swirls of the nebulae ; and so outwards and upwards 

 to that most glorious septum of all the visible creation, the radiant 

 ring of the Milky Way/' 



These subjects he pursued farther in an address to the Royal 

 Geographical Society on ' The Face of the Earth/ parts of which 

 were fortunately reported in Nature. Here it is pointed out 

 that the continents are merely the undrowned parts of 

 the submarine continental plateaux, which are the crests 

 of the folds and stand antilogous to the ocean troughs, on which 

 again the deeps correspond to the unsubmerged continents. 

 The dividing line comes midway down the submarine slope from 

 1,000 to 2,000 fathoms below sea level, the septum of the fold. 

 As might be expected from the fold theory, calculation has shown 

 that the area of the earth's surface on the continental side of this 

 line is equal to the area on the oceanic side of it ; while the volume 

 of water below its level is equal to the volume of land above it. 



Lapworth showed, too, that as there are three meridional crests 

 stretching from pole to pole, America, Europe-Africa, and Asia- 

 Australia, with three corresponding oceanic troughs, so there are 

 three longitudinal crests met in passing from N. to S., viz., North 

 America, South America, and the Antarctic Continent (the existence 

 of which he incidentally predicted on theoretical grounds) . 



Then he indicated and illustrated by diagrams that the inter- 

 ference of these sets of folds accounts for " (i) the form and 

 disposition of the terrestrial continents ; (2) the triangular shapes 

 of their extremities ; (3) the diagonal trends of their shores ; and 

 (4) the courses of the archipelagic lines." He dealt with the interfer- 

 ence and superposition of waves, the rhythmic repetition of forms 

 of lower order, possessing in miniature the characters of major 

 forms, and on this principle contrasted the straight and simple 

 West American wave and its deep, with the complex Alpine range 



* 4 8, p. 707. f 4 8, p. 706. } 48, p. 707. 50. 



