36 THE WONDERS OF GEOLOGY. Lect. I 



limit of the earth's atmosphere ; and the dark line, a, h, a 

 thickness often miles. The points d, e,f 9 g, indicate the alti- 

 tude of the highest mountains in the world ; * the depth of 

 the sea is shown by the line at the extremities of the 

 arc, a, h. As a thickness of 100 miles so far exceeds that 

 of the whole of the strata that are accessible to human 

 observation, we cannot doubt that disturbances of the 

 earth's surface, even to ten times the depth of those which 

 come within the scope of geological investigation, may take 

 place, without in any sensible degree affecting the entire 

 mass of the globe.f If these facts be duly considered, the 

 mind will be prepared to receive one of the most striking 

 propositions in modern geology — namely, that the highest 

 mountains were once beneath the sea, and have been 

 raised to their present situations by subterranean agency, — 

 some slowly, others suddenly, but all, geologically speaking, 

 at comparatively recent periods. 



* The highest peak of the Alps, and of Europe, is Mont Blanc, 

 which is 15,660 feet above the level of the sea — of the Andes, Chim- 

 borazo, which is 21,425 feet — and of the Himalayas, Dhwalagiri, 

 estimated at 28,000 feet, being more than five miles of perpendicular 

 altitude. 



f To convey a general idea of the relative magnitude of the in- 

 equalities of the earth's surface, Mr. Fairholme suggests the following 

 ingenious method. If we form a scale on the sand of the sea-shore in 

 the proportion of an inch to a mile, we shall have a circle of 8000 

 inches, or 222 yards in diameter, which when marked out with small 

 stakes, appears a very large area. Placing ourselves upon any part of 

 this circumference, we have an opportunity of taking a just, though 

 microscopic, view of the surface. The highest mountains in the world 

 would be represented by a little ridge five inches high ; the profound 

 abyss of the ocean by a groove of the same depth ; while the medium 

 inequality of sea and land would not exceed one inch. To form an 

 idea of smaller objects, we must examine an inch scale, finely gradu- 

 ated, by the aid of a microscope, and we shall then find that the tallest 

 man would be about the 880th part of an inch in height — the size of 

 the smallest animalcule observed in fluids, by the aid of the most 

 powerful microscope. 



