127 
The spot is undoubtedly that noted in Mr. Gardner’s paper, but 
their surroundings have been entirely different during my observa¬ 
tions. I have never seen them “ in a patch at the base of the cliff 
situated between the extremities of two unconformable sandy 
clay beds,” but always in masses of very tenacious blueish-white 
clay, which have fallen from some feet up the cliff, their precise 
origin being obscured by washings from the bed above. In this 
clay the seeds are embedded and invisible until after heavy rain, 
when the upper layers of clay have been dissolved and washed 
away, they then stand out on the surface and can be picked off, 
coated with white clay. There can be no doubt, I think, of their 
occurring thus in situ. The question arises, how did they come 
there ? 
In answering this question it will be convenient to here con¬ 
sider why seeds and leaves are usually found in these clay patches. 
Although the term “ leaf beds ” is commonly applied to the 
Bournemouth strata, there are actually no such beds in the sense 
of continuity. Leaves occur not in beds, but in lenticular 
lens-shaped) patches of clay. These are usually shaped like a 
spectacle lens, and lie horizontally in the cliffs, in line with the 
bedding planes, and usually with their long axes roughly east and 
west. In size they vary from a few feet to 30 or even 50 yards in 
length. (Plate XIV.). Clay beds do occur continuously for hun¬ 
dreds of yards, but these are not leaf beds, and usually have no 
fossils in them, nor are they lenticular in section. The process of 
exposure of a leaf-bearing clay patch is as follows:—A fall of 
the cliff face exposes first a thin narrow outer edge of clay, 
a further fall exposes a longer strip, which thins out at each 
extremity. If a fall slices off a surface of cliff which cuts the 
clay through its long axis, we have the largest exposure possible 
for that particular leaf patch. After this centre-line has been 
passed each fall exposes a shorter and smaller portion of the 
inner half of the clay, until a mere streak a foot or twcf long 
and an inch or two thick may remain. When this falls the 
particular “ leaf bed,” or “ clay patch,” has gone for ever. It 
is found that these patches have usually one or two species of 
leaves characterizing them, whilst only a few stray examples of 
other leaves occur. It thus happens that certain species tend to 
be peculiar to certain patches, where they may be very abundant, 
and but seldom found elsewhere even in adjacent spots. 
The explanation of the peculiar mode of occurrence of these 
clay patches with their leaves, throws a vivid light upon the 
conditions under which the flora flourished. Each of these 
patches represents the former bed of a pond, or small lagoon 
or backwater, through which water bearing clay in suspension 
slowly oozed and trickled from the swampy ground and marshes 
lying alongside the main channel of the river. Obviously the land 
was flat and of low level, for often the river overflowed its banks 
and swamped these ponds and lagoons with sand-bearing waters 
carried inland from the sandbanks of the estuary or river-mouth. 
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