ference or culture of man : and previous to the complete depar- 

 ture of the water from it, would at certain times be liable to be 

 covered by inundations ; and at others, when left dry, would be 

 exposed to the heat of the sun. The plants peculiar to these two 

 different states might also be expected to be produced. Hence 

 equiseta, reeds, and other aquatic plants, would, at one time, fill this 

 spot, which at another would be covered with a variety of filices, 

 and of other plants peculiar to the open and sun-burnt heath. 



Should the neighbouring mountains have contained iron, this, 

 dissolved by the various salts with which the water would be im- 

 pregnated, would be conveyed to spots where the water rested, and 

 where the decomposing organic matters were deposited ; and would 

 there be precipitated in the form of a brown oxide : this, uniting with 

 the superior and finer part of the earthy deposit, would cover the 

 decomposing vegetable matter with a stratum which, perhaps, after 

 no great length of time, would become that substance which is 

 known to mineralogists as bog-iron ore. But if, instead of the 

 water passing off, it should have long remained, and formed a large 

 and deep lake, then would other strata be successively added to 

 that which has just been mentioned. Sometimes these strata would 

 be furnished by the crumbled particles of the softer rocks, which 

 formed the sides of these immense and newly formed reservoirs ; 

 At other times, large masses of harder rocks would fall, undermined : 

 and, broken into pieces by the fall, would be sized and rounded into 

 boulders of various forms and magnitude ; or would be so far com- 

 minuted, as to be rendered the materials of future breccia, the 

 coarser sand-stones, &c. By the pressure of many of these suc- 

 ceeding strata, the lower ones would suffer a closer approximation 

 of their parts. The effects of this pressure are most observable in 

 those strata which have since become schisti, and which contain the 

 flattened remains of both vegetables and animals. The marks of 

 pressure are not, however, observable in all the strata, these effects 



