Bakewell^s Introduction to Geology, 355 



and that the strata have been deposited in succession, at dis- 

 tant epoch?. There is a note on the total quantity of salt 

 contained in the sea, which we think curious and original. 

 " T/ie inquiry has often been made, whence did the sea 

 derive its saline contents? It has been supposed, by some 

 naturalists, that the salt in the sea has been gradually aug- 

 mented by saline particles brought into it by rivers, but this 

 cause is totally inadequate to explain the immense quantity of 

 salt existing in the whole mass of the ocean. If the average 

 depth of the sea be ten miles, and it contains 2J per cent of 

 salt, were the water entirely evaporated, the thickness of the 

 saline residue would exceed 1000 feet." (p. 9.) Our author 

 proceeds to observe that, could this salt by any cause be re- 

 moved and spread upon all the present continents, it would 

 cover them with a stratum of solid rock salt, which would be 

 more than half a mile in thickness. 



The second chapter. On Petrifactions or Fossil Organic 

 Remains, is new. The penetration of animal or vegetable 

 substances with mineral matter, it appears from an experiment 

 of the late Dr. Jenner (stated p. 31.), may be effected in 

 a much shorter time than has been generally supposed; 

 it is, therefore, from the nature of these organic remains, 

 rather than from their state of preservation, that their 

 high antiquity can be inferred. Mr. Bakewell adopts the 

 Cuvierian classification of animals, and has given a succinct 

 account of the geological distribution of fossil remains belong- 

 ing to the four grand divisions which Cuvier has established 

 in the animal kingdom. What the author conceives most 

 particularly desirable is, to mark the first appearance of 

 those orders of animals whose organisation proves that they 

 existed under different conditions from the preceding orders. 

 The animals, for instance, that possessed organs for moving 

 on their bellies like the snail, and had heads and eyes, were 

 the inhabitants of shallow waters or of rocks near the surface ; 

 and the first appearance of vertebrated animals with feet, 

 indicates the existence of dry land or marshes in the vicinity, 

 at the period of their existence. 



Mr. Bakewell thinks that too much importance has been 

 attached by modern geologists to the minutiae of conchology. 

 " We know so little," he observes, " respecting the forms or 

 habits of the animals classed by the conchologist from their 

 shells, that we are far from certain, whether many shells 

 which are regarded as belonging to different species or even 

 genera, are not mere varieties of form, occasioned by differ- 

 ence of age or situation. In animals which have no internal 

 skeleton to determine their form, the construction of the ex- 



B B 2 



