part 2] PREGLACIAL FLORAS FROM CASTLE EDEN. 109 



and limestone species), Oxalis corniculata, Thymus serpijllum, 

 Clinopodium Nepeta, and Inula Gonyza (also a limestone species). 



Trees and shrubs are represented by Liquidainbar, Carpinus 

 laxiflora, JBefi/la alba, Alnus viridis and A. alutinosa, three 

 species of Crataegus, three Sub/, an Ilea, Rhus, Aral/a, Erica, 

 Solanum nigrum, and two species of Spiraea. There are a few 

 woodland plants, and it is noticeable that most of the mosses are 

 arboreal, or show a woodland association. 



The assemblage is altogether peculiar, both in the species present 

 and in those absent. The key to its interpretation seems to lie 

 in the numerical lack of water-plants and the predominance of 

 dry-bank species. The former character indicates that the stream 

 which laid down the deposit was too rapid for mud to accumulate 

 in its bed and plants to root themselves, the latter that the banks 

 were steep and dry ; the presence of chalk and limestone plants 

 suggests that the valley was probably cut in the Magnesian Lime- 

 stone of the district. In part, the glen or valley would seem to 

 have been clothed with woodland or coppice, in part with herbaceous 

 plants. By the stream must have grown some of the various 

 species of Cyperaceae, Sparganium ramosum, Alisma Plantago, 

 Ranunculus seel e rat us, and so on ; while very occasionally in a 

 pool or backwater a Potamogeton or Hippuris would find root 

 Or it may be they were carried into the stream by birds. 



The picture is that of an upland valley with steep hillsides, open, 

 or clothed with woods. If this interpretation of the facts be right, 

 it points to the existence in Middle Pliocene times, of an elevated 

 tract of land in the present North Sea area, near the Durham coast. 

 The land must have stood at least 400 or 500 feet above the then 

 sea-level for the stream to have had sufficient volume and force to 

 scour its channel, even if it were a short stream and quickly met 

 the sea ; but there is no indication among the plants found, of the 

 neighbourhood of the sea, with the possible exception of a nut 

 allied to Scirpm tabern&montani. This probably implies an 

 inland flora, and in that case it follows that the land must have 

 stood proportionately higher. In contrast to this inland aspect of 

 the earlier Pliocene flora, the later flora, represented with but one 

 exception by aquatic species, does show signs of the neighbourhood 

 of the sea, in the abundance of nuts of Scirpus taberncemontani. 

 It must be remembered, however, that, as the material in both 

 cases is transported, the deposits are probably derived from dif- 

 ferent areas, and need not represent successive stages of the same 

 area, although they may do so. 



The second point of interest in the botany has already been 

 touched upon : the presence of so many species belonging to the 

 Chinese-North American association. The existence of such an 

 association was first detected by us in the Teglian flora, but it was 

 not till we had examined the Ileuverian that its full significance 

 suggested itself. Since then, as the table (p. 107) shows, it has 

 been found very markedly in the Pont-de-Gail flora, and to a less 

 degree in that of Castle Eden. The most interesting species found 



