32 



OUTLINES OF GEOLOGY. 



Great Britain. Other remains are found, although rarely, 

 of animals, no living instance of whose species is now known 

 to exist, as the elk of Ireland. In the first case, however, 

 the animal is one well adapted to the climate ; and traditions, 

 in both Wales and Scotland point to a time at which it was 

 well known. In the latter case, we need not look to a date 

 for the existence of the fossil elk, more remote than the pre- 

 sent epoch of the earth's geological history, for it is not the 

 sole instance of a whole species having become extinct, not 

 merely in a single country, but throughout the globe, and it 

 is more than probable that others will disappear before the 

 powers of man. Some geologists, however, consider the 

 fossil elk as belonging to a more ancient formation. 



We not only find, in alluvium, the remains of man him- 

 self but those of the works of human art. These, in some 

 cases, carry us back to periods antecedent to any authentic 

 history. Thus the stone axes and arrow heads of England 

 mark a state of civilization no more advanced than that of 

 our own Aborigines ; and canoes have been discovered in 

 France, in these formations, like those of the Indians, and 

 South Sea Islanders. 



71. Besides the vegetable matter contained in the swamps 

 and mud, large beds of trees are found in the alluvium, and 

 particularly in the deltas of seme rivers. This is particu- 

 larly the case in the delta of the Mississippi ; and in some of 

 its arms and branches, they have formed rafts, which impede 

 the navigation for hundreds of miles. These trees are such 

 as grow, at present, on the banks of the stream. 



ORDER II. CHEMICAL. 



' 72. The modern chemical formations may be classed as 

 calcareous, silicious, saline, inflammable, and metallic. 



