CHAPTER XIV 



AGE AND AREA FROM A 



PALAEOBOTANICAL STANDPOINT 



By Mrs E. M. Reid, B.Sc, F.L.S. 



Any student of ancient floras must feel that in its power to 

 meet the facts of geology and palaeobotany lies the supreme 

 test of Dr WiUis' theory of Age and Area. The time has not come 

 when such a test can be applied Avith any degree of fullness, for 

 the history of Tertiary floras, which are those chiefly concerned, 

 is still but imperfectly known; and more especially is this true 

 of their migrations. Nevertheless, even if we cannot make a full 

 comparison, it may be of use to make a beginning, by comparing 

 such conclusions as have been reached by the two studies; not 

 only for the sake of testing a new theory, but because, if it holds, 

 palaeobotany has much to learn from it of the past history of 

 plant-life and must therefore reconsider its conclusions in the 

 light of new knowledge. 



In what follows I do not propose to go much bej^ond the range 

 of my own studies, but these have been largely concerned with 

 the questions of which Age and Area treats, the migration of 

 floras, the age of species, and the extermination of species. The 

 material of study has been the Pleistocene floras of Britain, and 

 some late Tertiary floras of West Europe, chiefly the following 

 Pliocene floras: Cromerian (East Anglia), Teglian (Holland), 

 Castle Eden (Durham), Reuverian (Dutch-Prussian border), 

 Pont-de-Gail (Cantal). These have been investigated by an 

 examination of seeds and fruits. 



Plant Migration. If there is one fact which has emerged 

 more clearly than another from the study of Pleistocene and late 

 Tertiary floras in West Europe, it is that at different geological 

 times, different floras have occupied the same locahty. By 

 "different floras" is meant different assemblages of plants which 

 have lived in the past, as they do in the present, in regional, or 

 in ecological association, more especially in climatic association. 



Thus, by the quantitative study of pollen-grains in the suc- 

 cessive horizons of the peat-bogs of Scandinavia, it has become 

 possible for Scandinavian workers to trace successive assemblages 



