Chalk and Flint Formation. 5 



a cloud of hot lime dust fell through an atmosphere 

 abounding in carbonic acid, might not that have a 

 similar effect ? 



Manifestly the hypothetical insect manufacturers 

 of the chalk are both utterly incompetent to serve as a 

 cause, and also wholly superfluous. Chalk may be 

 got better without them. 



The parallel case of limestone may be referred to 

 for illustration. In a vast number of cases it con- 

 sists largely of shells, as we see abundantly in many, 

 if not most marbles ; whence some geologists came 

 to the couclusion that all limestones had originated 

 in organized substances, and the eminent Dr. Mac- 

 culloch adopted the opinion. On this Sir Charles 

 Lyell expresses the following judgment : " When it 

 is hinted that lime may be an animal product com- 

 bined by the powers of vitality from some simple 

 elements, I can discover no sufficient grounds for 

 such an hypothesis, and many facts militate against 

 it." 5 The same he might have said of chalk. 



Moreover, how stand the grand facts of the Chalk 

 Formation ? It has, no doubt, in many cases been 

 elevated from under the sea to those cliffs which now 

 overhang it at considerable height, and are lashed 

 by the waves at the base; and it presents abun- 

 dantly fossil remains of fish and saurians. But the 

 enormous masses of carbonate of lime are said to 

 compose nearly one-eighth part of the superficial 

 crust of the globe ; and the chalk formation occupies 

 extensive stretches of the land, across whole con- 

 tinents, and that in well-defined lines and breadths, 

 reaching to great depths in the thickness of the 

 deposit. It has been maintained, of course, that all 



5 Lyell, "Principles," vol. ii., p. 532, 10th Edition, 1868. See 

 also his " Manual of Geology," p. 49. 



