348 THE CAUSES OF THE xi 



careful observations and soundings of the bottom 

 of the Atlantic; and although, as we must all 

 regret, that up to the present time that project has 

 not succeeded, we have the satisfaction of knowing 

 that it yielded some most remarkable results to 

 science. The Atlantic Ocean had to be sounded 

 right across, to depths of several miles in some 

 places, and the nature of its bottom was carefully 

 ascertained. Well, now, a space of about 1,000 

 miles wide from east to west, and I do not exactly 

 know how many from north to south, but at any 

 rate 600 or 700 miles, was carefully examined, and 

 it was found that over the whole of that immense 

 area an excessively fine chalky mud is being 

 deposited ; and this deposit is entirely made up of 

 animals whose hard parts are deposited in this 

 part of the ocean, and are doubtless gradually 

 acquiring solidity and becoming metamorphosed 

 into a chalky limestone. Thus, you see, it is quite 

 possible in this way to preserve unmistakable 

 records of animal and vegetable life. Whenever 

 the sea-bottom, by some of those undulations of 

 the earth s crust that I have referred to, becomes 

 up-heaved, and sections or borings are made, or 

 pits are dug, then we become able to examine 

 the contents and constituents of these ancient sea- 

 bottoms, and find out what manner of animals 

 lived at that period. 



Now it is a very important consideration in its 

 bearing on the completeness of the record, to 



