20 
and also at Hor, in Scania. The origin of tins deposit 
(confining ourselves to that on our own coast) is a very 
difficult problem to solve, for whether we suppose the plants 
to have grown on the spot, or to have been transported by- 
currents into some estuary or bay, we are equally beset 
with improbabilities. Yet to one of these two theories we 
must look for the solution. In the first place, could so small 
a portion of our island have had a peculiar flora during 
this epoch ? This is barely possible to conceive, unless we 
assume it to have been insular during the above period. 
Or, in the second place, can we suppose that currents 
could throw masses of vegetables of a particular character 
upon this one district, and not spread simultaneously a 
portion of the same upon the contiguous and contempora- 
neous beds of Oolite and Lias, in the neighbourinc; counties? 
as Sir H. De la Beche thinks, who says " Circumstances 
must have existed at such situations, during a particular 
part of the deposit, not common to a considerable surface, 
such, perhaps, as sheltered bays, into which the vegetables 
were drifted, with mud and sand."* If, however, this last 
theory is adopted, the question arises, From whence were 
they drifted ? as the locality could not be far distant, on 
account of the high state of preservation of most of the 
specimens ; for here alone, I believe, have been found ferns 
with the Sori or masses of fructification on the back of 
their fronds, which long transportation would have dislodged. 
The stems, also, of Equisetum columnare, which here 
occur in the Sandstone in an erect position, would, as Mr. 
Williamson justly remarks, if this had been the case, be 
more disjointed and compressed, while, on the contrary, 
they often retain all their original roundness. As, however, 
we cannot point to the proximity of land, at the present 
day, where the same flora is more extensively distributed, 
* Geological Manual, p. 71. 
