LAMARCK'S WORK IN GEOLOGY \\\ 



face of the terrestrial globe is immutable. They 

 teach us that the vast ocean which occupies so great 

 a part of the surface of our globe cannot have its 

 bed constantly fixed in the same place ; that the dry 

 or exposed parts of this surface themselves undergo 

 perpetual changes in their condition, and that they 

 are in turn successively invaded and abandoned by 

 the sea. 



" There is, indeed, every evidence that these enor- 

 mous masses of water continually displace themselves, 

 both their bed and their limits. 



" In truth these displacements, which are never in- 

 terrupted, are in general only made with extreme 

 and almost inappreciable slowness, but they are in 

 ceaseless operation, and with such constancy that the 

 ocean bottom, which necessarily loses on one side 

 while it gains on another, has already, without doubt, 

 spread over not only once, but even several times, 

 every point of the surface of the globe. 



" If it is thus, if each point of the surface of the 

 terrestrial globe has been in turn dominated by the 

 seas — that is to say, has contributed to form the bed of 

 those immense masses of water which constitute the 

 ocean — it should result (i) that the insensible but un- 

 interrupted transfer of the bed of the ocean over the 

 whole surface of the globe has given place to depos- 

 its of the remains of marine animals which we should 

 find in a fossil state ; (2) that this translation of the 

 ocean basin should be the reason why the dry por- 

 tions of the earth are always more elevated than the 

 level of the sea ; so that the old ocean bed should 

 become exposed without being elevated above the 

 sea, and without consequently giving rise to the for- 

 mation of mountains which we observe in so many 

 different regions of the naked parts of our globe." 



Thus littoral shells of many genera, such as Pec- 

 tens, Tellinse, cockle shells, turban shells (sabots), etc., 



