284 
THE GEOLOGIST. 
Till iu 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. 
Sucli 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, Serpulae, and other encrusting bodies, 
can we doubt their having lain at the bottom of the sea after death, 
