PALEOBOTANY 



S8i 



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

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



Bf Bs Bm S M O-W 



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 

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

 disjjlacing one another, belong to the following major groups: (r) O. W., 

 open water succession; (2) M., marginal succession; (3) 5., 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.) (.\fter Bray.) 



also transport quaritities of plant' (and animal) frag- 

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

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



