284 



THE GEOLOGIST. 



Till in sheltered coves and reaches 



Of sandy beaches 

 All have found repose again/' — 



so in former ages, the finer particles of earth derived from the waste 

 of the land were carried by the currents of the ocean miles and 

 miles away, and, deposited in its tranquil depths, have formed those 

 important argillaceous, calcareous, and sandy strata of which the ex- 

 ternal crust of our globe is mainly composed. 



Such operations and the accumulation of organic debris, chiefly of 

 a microscopic character, effected the deposition, and volcanic or some 

 other equally powerful internal force, the elevation of those great 

 masses of stone, sand, and clay, which are grouped by geologists to- 

 gether as the Cretaceous formation. 



The fossil shells, fishes, echini, and sponges of the Chalk and its 

 associated beds, clearly prove their marine origin ; while the remains 

 of sharks, nautili, ammonites, and other forms of animal life usually 

 predominant in warm latitudes, are, without going into more minute 

 details, sufficient to indicate the warmer temperature and different 

 climatal conditions of our geographical region during the Cretaceous 

 era. 



Of the many records of the past, nothing is useless ; no portion 

 without its value. The embedded shells give us important evidence 

 of the rate of the accumulating sediments, and record their progress. 

 In the beds we are studying, especially in regard to the Chalk, they 

 teach us how slow and gradual was the deposit of sediment ; for the 

 encrusting parasites on fossil bones and shells, betoken how long 

 these dead objects lay in the ocean-depths ere they were finally en- 

 tombed in their massive grave. 



How slowly and solemnly did the mighty work proceed ; how vast 

 the period over which it extended. Each of all the myriads of those 

 departed beings whose remains teach us the history of their age, 

 must have had its term of existence, have lived and died, as do the 

 creatures of the present, ere the growing cemetery enclosed it in its 

 " cold embrace." 



" When we see," says Lyell, " thousands of full-grown shells dis- 

 persed throughout a long series of strata, we cannot doubt that time 

 was required for the successive multiplication of successive genera- 

 tions ;" nor when we see the internal parts of fossil oysters and other 

 shells covered with Bryozoans, Serpulaa, and other encrusting bodies, 

 can we doubt their having lain at the bottom of the sea after death, 



