88 ; 
Woods of North-East Kent. 
(b) Woods on the Clay soils of the Woolwich and Reading series. 
An area of this type has been investigated in Farningham Wood, near 
Swanley. 
The coppice on the Clay differs from that on the sand and gravel in 
the larger number of woody species present. Chestnut, Hazel, and Ash are 
of frequent occurrence, while Oak, Birch, Beech, Populus tremula , L., and 
Salix Caprea , L., are found sparingly. Many of the herbaceous plants 
found on the sands and gravels also occur on the Clay, but the vegetation, 
as a whole, is of the mesophytic type. Calluna Erica , DC., and Air a 
flexuosa, L., are not found. 
After felling, Carduus pains tris, L., is produced in great abundance, and 
Lysimachia nemorum , L., Scabiosa Snccisa , L., Circaea lutetiana , L., and 
Juncoides sylvaticum , O. Kuntze, are usually present in considerable 
quantity. Small ponds are of frequent occurrence, and in their vicinity 
Lysimachia Nummular ia, L., Polygonum Hydropiper , L., and J uncus con - 
glomeratus , L,, are characteristic plants. 
Clay soils of this type usually support an abundant bryophytic flora. 
Several of the more xerophytic species of the sands and gravels, such as 
Polytrichum juniperinum , Willd., and Dicranella heieromalla , Schp., are 
absent, and these are replaced by Catharinea undulata (L.), Web. Mohr., 
Mnium hornum , L., Mnium undulatum , L., and othor mesophytic species. 
Pellia epiphylla , L., frequently covers large areas, and Riccia glauca ) L., is 
often found. 
The Oldhaven (Blackheath) Formation. 
In the districts under consideration the Oldhaven deposits consist 
largely of rounded flint pebbles. The soils produced by these beds are 
poor and stony in character and in consequence are rarely cultivated. The 
proportion of calcium carbonate is lower than in the soils of the two Eocene 
formations already described, varying from 002% to 0-05% of the dry weight 
(Hall and Russell (7)). The acidity in woodland areas is very pronounced. 
In these districts the Oldhaven beds are of small extent and are found 
capping some of the Tertiary outliers. Farningham Wood, near Swanley, 
covers almost the whole of an outlier of this kind. Towards the outside of 
this wood there is a continuous zone of Thanet Sand ; immediately within 
this is found a similar zone of Woolwich and Reading deposits, while the 
central and highest portion of the wood is situated on the Oldhaven beds. 
Perry Wood, near Faversham, has a similar conformation (Text-fig. 4). 
The investigations made have been carried out in Farningham and 
Perry Woods. The woods occurring on the Oldhaven beds are of the Oak- 
Birch-Heather type referred to by Moss, Rankin, and Tansley ( 13 ). They 
consist for the most part of open coppice in which the trees are few in 
