250 RECENT FORMATIONS. 



they be, present a curious but difficult chapter in world- 

 history; curious as displaying more clearly than the older 

 formations their whole origin and progress, but, like modern 

 human history, difficult of narration, from the exuberance 

 and nearness of the details. Approaching our own times, 

 their interest is proportionally increased, and he who under- 

 stands them aright cannot fail to catch by reflection a clearer 

 insight into the cycles and systems that went before. In 

 their origin and formation we see a repetition of the origin 

 and formation of all the older formations, hence their in- 

 structiveness as a study ; while in their superficial disper- 

 sion they become the immediate source of sustentation to 

 the plants and animals that inhabit the terrestrial surface. 



Arising from the operations of waste and reconstruction 

 described in Sketch No. 2, these Eecent, or, as they are 

 sometimes termed, Superficial Accumulations, will be as 

 multifarious as the agencies concerned in their formation ; 

 and hence perhaps the most intelligible way of treating 

 them is to. arrange them according to the agents more im- 

 mediately concerned in their production. In this way we 

 will have Fluviatile formations, or those arising from the ac- 

 tion of rivers ; Lacustrine, or those formed in lakes ; Estua- 

 rine, in estuaries; Marine, in seas; Chemical, arising from 

 chemical action; Organic, from the growth and decay of 

 plants and animals ; and Volcanic, from the internal fire- 

 forces of the globe. There will be older and younger, of 

 course, among these different formations some so old as to 

 imbed the remains of plants and animals no longer inhabiting 

 the same localities, and others so recent as to belong entirely 

 to the current age, and indeed to be still in process of forma- 

 tion. To display them, whatever their age, in intelligible 

 order, is the object of the present Sketch ; and he who bears 

 in mind the operations of waste and reconstruction de- 

 scribed in a previous paper, can have no difficulty in fol- 



