480 ON THE SUCCESSIVE FORMS 



general principle is not affected. If, during the pre- 

 sent state of the surface, several alternations of peat 

 and earthy matters can he formed in our lakes and 

 ^estuaries, much more numerous ones might have 

 been produced in antient periods, under greater du- 

 ration, and under variations of the state of the sur- 

 face, the chief of which, as bearing on this question, 

 I shall shortly explain. " 



Here then is a state of the earth, during which a 

 large portion of it, laid dry, contained cavities, lakes 

 or basins or aestuaries, in which were preparing a 

 peculiar set of strata ; while that period of repose is 

 measured by the depth of the coal series in anyplace: 

 and as we know that in some, it is very considerable, 

 the period in question must have been correspondently 

 great. But while these deposits were forming above 

 the sea, it is plain that others must have been also 

 forming below it ; and the depth of those will corre- 

 spond, under differences which we shall never know, 

 with those of the coal strata; being formed during 

 the same period of repose. This could not have been 

 otherwise; and we must therefore expect to find, that 

 as the coal strata are not every where intermediate 

 between the inferior set and that which follows them, 

 some other strata must, in particular places, be found 

 occupying that space. Such marine strata must be 

 parallel in time, but not in order, with those of the 

 coal series ; although, having been afterwards sub- 

 jected to the same revolutions, they must correspond 

 with them in their new positions or elevations. Thus 

 then the strata of this epocha must present complicated 

 appearances : seeming to have been formed at different 

 periods, when they have been simultaneous, and the 

 differences depending on those of their receptacles. 



Geologists have not yet produced satisfactory de- 



