312 IMMENSE Q UANTITIES OF SHELLS. 



of them are valuable, inasmuch as they inhabit the seas at 

 such depths as not to be known in the living state. 



The number of shells is far, very far beyond human cal- 

 culation. An examination of the rocks on the English sea- 

 shore during the summer will prove this in a slight degree. 

 These are so covered with shells that scarcely a pin^s point 

 could be introduced between them. Many apparent grains 

 of chalk are in reality microscopic shells and fragments of 

 marine coral, of w^hich upwards of a thousand have been ob- 

 tained from one pound of chalk. 



The most level and lowest parts of the earth, when pene- 

 trated to a very great depth, exhibit nothing but horizontal 

 strata, composed of various substances, and containing, 

 almost all of them, innumerable marine productions. Similar 

 strata, with the same kind of productions, compose the hills 

 even to a great height. Sometimes the shells are so numer- 

 ous as to compose the entire body of the stratum. They 

 are almost in such a perfect state of preservation, that even 

 the smallest of them retain their most delicate parts, their 

 sharpest ridges, and their finest and most tender processes. 

 They are found in elevations, far above the level of every 

 part of the ocean, and in places to which the sea could not 

 be conveyed by any existing cause. The summits of the 

 Pyrenees and the Andes, at the height of thirteen or four- 

 teen thousand feet above the level of the sea, present them 

 to our notice. 



The sea-banks and coasts are covered with broken shells, 

 of which lime is the ingredient. This generally exists in 

 the state of carbonate, the same as in chalk, common lime- 

 stone, and marble. Many of the more tender shells and 

 shelly matters are broken by the agitation of the waters, 

 and form a variety of sand which is truly a product of the 

 sea, and forms a valuable manure on land. Great deposits of 

 this article are found oh the coasts of Devonshire and Corn- 

 wall, and in many other parts of tlie British coast. 



