[PENHALLOW] DEVELOPMENT OF CERTAIN MARSH LANDS 31 
macrocarpon. This identification was made by means of the remarkably 
well preserved leaves which often retained their green colour to an 
astonishing extent. It is clear from the nature of the evidence obtained, 
that this layer represents what is now recognized in all bog formations 
as the cassandra zone, the position of which is here correctly indicated. 
The base of the cassandra zone merges somewhat insensibly with what 
may be termed the basal member of the series—a stratum of indefinite 
thickness. The upper portion of this stratum contains numerous 
remains of marsh plants in the form of leaves, rhizomes, etc., in some 
of which the colour is preserved in a remarkable manner: but the 
progress of decay has rendered them all exceedingly soft and they 
could not be handled. Comparisons with the vegetation of neighbouring 
bogs leads to the belief that they represent Cyperacee, Typhacee 
Iridaceæ, Juncaceæ and possibly Nympheaceæ. At all events, the evi- 
dence is clear that they were derived from aquatic and semi-aquatic fresh 
water types of plants. 
The dominant vegetation of the lowest zone is of a wholly different 
character. Reference has been made to the fact that at the bottom of 
the trench, the partly decayed material could be pitched out with a fork 
like hay, from which fact we may draw the inference that it was very 
long and fibrous. An examination showed this material to be almost 
pure sphagnum forming a layer of almost indeterminate thickness, the 
upper portions of which carried the remains of characteristic aquatics. 
Tt should be further pointed out that this sphagnum was found to be 
continued in diminishing quantities through the two zones lying imme- 
diately above, and so up to the layer of peat containing the large pine 
trees. Its presence affords evidence as to the continuance with diminish- 
ing force, of conditions of great moisture. 
From the facts thus recited it becomes possible to give a complete 
and connected historical account of the formation of this marsh from 
the very earliest period of development, and for this purpose it will be 
desirable to reverse the order so far discussed, and to deal with the 
various events in their proper sequence. 
An examination of the topography of the region shows very clearly 
that, at some former period, which, for convenience sake we may assume 
to ceincide with the Pliccene, the immediate region under consideration 
was characterized by the presence of depressed areas or basins lying 
between the mainland and a series of rocky islands which fringed the 
coast. Such basins may have become partly filled with silt at a later 
period, and their depth thereby reduced, and although no attempt I ; 
been made to prove this by direct exploration, the evidence afforded by 
adjacent localities would seem to favour the belief that Pleistocene clays 
