106 Things not generally Known. 



WHY SEA-SHELLS ABE FOUND AT GREAT HEIGHTS. 



The action of subterranean forces in breaking through and 

 elevating strata of sedimentary rocks, of which the coast of 

 Chili, in consequence of a great earthquake, furnishes an ex- 

 ample, leads to the assumption that the pelagic shells found 

 by MM. Bonpland and Humboldt on the ridge of the Andes, at 

 an elevation of more than 15,000 English feet, may have been 

 conveyed to so extraordinary a position, not by a rising of the 

 ocean, but by the agency of volcanic forces capable of elevating 

 into ridges the softened crust of the earth. 



SAND OF THE SEA AND DESERT. 



That sand is an assemblage of small stones may be seen 

 with the eye unarmed with art ; yet how few are equally aware 

 of the synonymous nature of the sand of the sea and of the 

 land ! Quartz, in the form of sand, covers almost entirely the 

 bottom of the sea. It is spread over the banks of rivers, and 

 forms vast plains, even at a very considerable elevation above 

 the level of the sea, as the desert of Sahara in Africa, of Kobi 

 in Asia, and many others. This quartz is produced, at least 

 in part, from the disintegration of the primitive granite rocks. 

 The currents of water carry it along, and when it is in very 

 small, light, and rounded grains, even the wind transports it 

 from one place to another. The hills are thus made to move 

 like waves, and a deluge of sand frequently inundates the 

 neighbouring countries : 



" So where o'er wide Numidian wastes extend, 

 Sudden the impetuous hurricanes descend." Addisoris C'ato. 



To illustrate the trite axiom, that nothing is lost, let us 

 glance at the most important use of sand : 



"Quartz in the form of sand," observes Maltebrun, "furnishes, by 

 fusion, one of the most useful substances we have, namely glass, which, 

 being less hard than the crystals of quartz, can be made equally trans- 

 parent, and is equally serviceable to our wants and to our pleasures. 

 There it shines in walls of crystal in the palaces of the great, reflecting 

 the charms of a hundred assembled beauties ; there, in the hand of the 

 philosopher, it discovers to us the worlds that revolve above us in the 

 immensity of space, and the no less astonishing wonders that we tread 

 beneath our feet." 



PEBBLES. 



The various heights and situations at which Pebbles are 

 found have led to many erroneous conclusions as to the period 

 of changes of the earth's surface. All the banks of rivers and 

 lakes, and the shores of the sea, are covered with pebbles, 

 rounded by the waves which have rolled them against each 



