36 NATURAL HISTORY. 



we cannot exactly know the proportion between the 

 surface of the earth and that of the sea ; only as much 

 as may be judged by inspection of what is known, 

 there is more sea than land. 



If we would have an idea of the enormous quantity 

 of water which the sea contains, let us suppose one 

 common and general depth to the ocean; by comput- 

 ing it only at 200 fathoms, or the 10th part of a mile, 

 we shall see that there is water sufficient to cover the 

 whole globe to the height of 600 feet of water, and if 

 we would reduce this water into one mass, we shall 

 find that it forms a globe of more than 60 miles diameter. 

 The form of the earth is not that of a perfect globe, 

 but rather what is termed a spheroid, a globe which is 

 flattish at the poles, the axis, therefore, or line, which 

 may be supposed to pass through it at the equator, is to 

 its axis at the poles in the proportion of 230 to 229- 

 The solid parts of the earth are formed of beds or strata 

 of different materials, which lie one upon another in a 

 regular order. The first stratum consists of common 

 soil, mixed with a variety of decayed vegetable and 

 animal substances, and with stony and sandy particles. 

 In different parts of theworld the other strata are found 

 to consist of different materials, and differently dispos- 

 ed. In some parts the strata are horizontal, in others 

 they are inclined ; and veins or fissures of metals, coals, 

 and other minerals, frequently penetrate through the dif- 

 ferent beds or strata to a great depth, and divide them. 

 At Marly-la- Ville in France, which is a high country, 

 but flat and fertile, the following strata were found ar- 

 ranged horizontally. From the shells which were found 

 in N" 16. we may conjecture, that at some period the 

 soil of Marly-la- Ville was the bottom of the sea, but 

 has since been raised to the height of 75 feet. 



