The 



Scottish Botanical Review 



No. 3] 1912 [July 



The Geological Relations of Stable and Migratory 

 Plant Formations. By C. B. Crampton, M.B., 

 CM., of H.M. Geological Survey. 



( Continued from p. 79.) 



Part V. The Geological Relations of the 

 Migratory Plant Formations. 



The great pile of sediments, dating from the Precambrian 

 onwards, stands witness that erosion and deposition have 

 prevailed throughout geological time. Stratigraphy has fully 

 borne out Lyell's dictum, that the geological workings of the 

 past are to be measured by a study of those now in operation, 

 and, for the purposes of the present argument, we may safely 

 assume that the physiography of past epochs was governed 

 by statical and dynamical factors approximately similar to 

 the present ones. 



Sea-cliffs have always evolved at exposed points of the 

 sea's margin. Beaches have formed along the line of shore- 

 drift from places where cliff erosion afforded sufficient 

 durable material to be pounded into shingle by the waves, 

 but temporarily resist further dispersal. Sand has constantly 

 accumulated in the shallower bays of exposed coast-lines, 

 where the coastal currents slackened, and the sand, driven 

 shoreward by the waves, has undergone exposure between 

 tide-marks, to be captured by the winds, and built into 



VOL. I. 127 10 



