128 
which we have seen (p. 122) was close by. 1 he sard same 
as the flood water subsided, and was left in a layer upon the 
dav, to be followed by further layers of clay again deposited in 
tranquil times. The trees and ferns whose leaves we find in the 
clay grew in the immediate neighbourhood, and their leaves were 
carried by wind and floated down by water to these ponds and 
lagoons, there to be entrapped and finally to sink and be enveloped 
in the clay at their bottoms, thus were formed layers of leaves 
embedded in clay. The land appears to have been slowly sink¬ 
ing at this period, and so in time the lagoons and ponds became 
choked up with sand and thick layers of mud which were deposited 
over them from the adjacent estuary. These later deposits were 
usually unfossiliferous, but often contained ground-up woody 
matter, which formed layers of lignite, all effectively sealing up 
the leafy clay bed of the former pond, until its remains were again 
revealed as a" leaf-bed ” in our cliff-face of to-day. 
The prevalence of certain trees growing together in patches 
of drier ground, and of ferns and marsh plants flourishing in 
lower parts, will account for the fact that the clay patches con¬ 
tain leaves of the flora that lived nearest to them, or near which 
the streams flowed that supplied them. The phenomenon of the 
seed patch is, perhaps, less easy to explain. It may be that 
the seeds were retained in an eddy which caught them up whilst 
the lighter floating leaves were carried on to be deposited else¬ 
where. 
From these considerations it is easy to understand that with 
frequent falling of the cliffs their palaeontological features are 
always changing. Many of the spots formerly described as yield¬ 
ing certain leaves have long since ceased to do so, the lenticular 
clay patches having vanished with successive falls of the cliff face. 
Few, indeed, of those of a decade ago now exist. On several 
occasions I have found a little patch of cinnamon-coloured clay 
crowded with leaves in the cliff face, only to be disappointed at 
finding it thin out and disappear in a few inches, proving that it 
was actually the last fragment, or innermost edge, of what had 
been a much larger mass. There can be no doubt that during 
the last thirty years these leaf-bearing patches of clay have 
become much scarcer. And the explanation seems to be that 
as the cliffs fall their face displays sections that are further and 
further removed from the main channel or mouth of the river. 
Naturally, the further inland we go the fewer and scarcer would 
the ponds and lagoons become, as all were fed and maintained 
by the river and its tributary streams. We must expect, 
as indeed is the case, that leaves will become scarcer and good 
specimens more difficult to find each year. And to crown all, 
the ruthless march of civilization comes at last to seal up forever 
from geological research what remains of the most interesting 
section of our cliff's by the new Undercliff Drive! 
From some yards eastward of the “ seed-patch” to Boscombe 
Pier the distinction between the lower marine beds and the upper 
