H. ie Howorth— Traces of a Great Post-Glacial Flood. 115 
has been able to point out any estuary beds, containing estuary fossils, 
along the valleys at high levels. Why, also, should we not see some 
more distinct lines of old sea-cliffs and sea-caves at higher altitudes, 
and, likewise, some heavy masses of blown sand and shells like what 
we find on the coast at present? The beds of glacial marine clay 
and sand have been destroyed along the valleys to an extent inex- 
plicable on the supposition that the sea gradually retired and nothing 
but ordinary subaerial action followed. In certain low districts, 
where this clay has nearly all disappeared, patches of it are left on 
eminences and places just where we might suppose it most likely to 
have escaped the action of glaciers [say, rather, of floods of water.— 
H. H. H.|; and at the mouth of some valleys (as, for example, that 
of the Dee, at Aberdeen) we find masses of it, which seem to be 
denuded remains of beds that some powerful agent has swept clean 
out of all the rest of the valley. And some of these beds appear to 
have been dislodged from their original position and thrust out sea- 
wards in a confused mass, as in the banks near the Aberdeen light- 
house and powder-magazine” (Journ. Geol. Soc., vol. xxx. pp. 318 
and 319). 
Let us now turn to the marine drifts in the valley of the Severn, 
which have given rise to the hypothesis of an arm of the sea having 
once occupied this area, to which the name of the Straits of Malvern 
has been given. Of the shells in these beds Mr. Maw says he could not 
find that any species are peculiar to particular parts of the deposit, 
but the fragments of shells are distributed throughout the whole 
mass of drift, including the clay and gravel beds. They are very 
fragmentary, only six or seven being perfect out of several hundreds. 
“Of that massive and strong shell, Cyprina Islandica,” he says, “ I 
have detected nothing but fragments scarcely an inch across and 
mostly much broken. The broken and water-worn condition of 
these remains would support the idea of their long transit from 
perhaps northern latitudes; but the evidence before us of the 
repeated tearing up and redeposition of the beds in which they 
occur would also account for their fragmentary state... . At the 
point where the drift beds rest against the old coast-line of Wenlock 
Shale I made a careful examination of the water-worn surface, with 
the object of ascertaining if some of the shells occurred in situ, but 
found nothing different from the usual state: all were broken and 
fragmentary ” (Journ. Geol. Soc., vol. xx. p. 189). All this surely 
points most strongly to these beds having been completely moved 
and re-arranged. If it had been the case of a mere submergence of 
the area, the shells would have been found in situ, and widely 
distributed; and I have no doubt myself that the real explanation 
of the presence of the marine shells here is that they were 
brought hither by that mighty wave of waters whose presence 
we have tracked in so many quarters, and which swept them 
into their present quarters either from the Bristol Channel in the 
South or from the North—most probably from the South. The 
same result follows if we examine, not the shells, but the beds 
inclosing them, which do not have their constituents arranged the 
