PALEOBOTANY 



581 



ing into inland lakes or into the ocean. In addition to 

 rock-sediment eroded from the surface of the land, streams 



^<i;&*Kl:<f£ 



Bf Bs Bm 5 M O-W 



MF Bf Bs.Bm. 



A^l 



^y:^ 



iir^^fi 



' />o^* 



Fig. 412. — Diagram illustrating the gradual filling up of lakes by the 

 encroachment of vegetation, and also the stages in the origin of peat and 

 rnarl deposits in lakes. The several plant associations of the Bog series, 

 displacing one another, belong to the following major groups: (i) O. W., 

 open water succession; (2) M., marginal succession; (3) S., shore succes- 

 sion; (4) B., bog succession, comprising the bog-meadow {Bm), bog-shrub 

 {Bs) and bog-forest {Bf); and (5) M. F., mesophytic forest succession 

 (Cf. Fig. 411.) 



also transport quantities of plant (and animals) frag- 

 ments, leaves, stems, pieces of bark, fruit, flowers, pollen 

 and spores, roots, and even entire plants. These natur- 



