THE HISTORY OF PLANT LIFE. 21 



to be met with at Leasowe and other places about the coast 

 of Great Britain examples of plants which have been preserved 

 in place, and from which, therefore, we may draw important 

 inferences respecting their former environment and habits of 

 growth, but such examples are comparatively rare. The great 

 bulk of the material with which the palaeobotanist has to deal 

 has been displaced, chiefly through the action of water, as exem- 

 plified at the present day by such great rivers as the Amazon, 

 Mississippi, or Nile. The evidence of such transport is gen- 

 erally conspicuous and admits of little if any doubt. Thus, in 

 the woods so abundant in certain Pleistocene deposits, the usu- 

 ally small fragments show in their worn surfaces and rounded 

 angles all the characteristic features which can come only 

 through long immersion in water and the prolonged action 

 of waves, or transport over considerable distances. In the 

 banks of the Moose and Missinaibie rivers, which run from 

 near the north of Lake Superior to James Bay, extensive 

 deposits of moss, lying under a depth of fifty feet of soil, and 

 consisting chiefly of Hypnum and Distichium, occur. These 

 deposits are characterized by the compressed, flaky form of the 

 material, the flakes being separated by silt consisting of sand, 

 and commonly enclosing fragments of wood which have been 

 worn by the prolonged action of water. The evidence here 

 indicates that the material must have had its origin near the 

 head waters of the rivers, that it was carried down to a point 

 near the mouth, and there deposited in pockets, as now found. 

 As, at the present day, vast quantities of plant remains are 

 washed down the tributary rivers into lakes or into the ocean 

 itself, so must we consider that the same process has been oper- 

 ative during all the ages through which the earth's crust has 

 been undergoing continual change. Few examples offer more 

 instructive lessons relative to the general conditions under which 

 plant remains become buried by successive layers of sand and 

 mud, and eventually converted into fossilized forms, than those 

 which occur upon almost any ocean beach. Here we note in 

 one enormous mass the commingling of land and marine plants 

 which, in conformity to conditions of topography, wind, and 

 currents, are commonly localized in a particular place, and there, 



