250 CROFTS : NOTES ON ALEXANDRA DOCK EXTENSION, HULL. 
H.W.O.S.T. The peat was covered with a stiff grey marly clay, 
generally serving as a matrix, filling up all hollows, with its 
upper surface almost perfectly horizontal and level. In this bed 
were cherry stones in considerable quantity, and many quite 
perfect cherries [Primus padus) were found preserved in this clay. 
At a point near the north-western angle of the dock, the clay 
filled up a depression in tlie underlying beds near its upper 
surface, and towards the northern edge of the depression a group 
of small pieces of charcoal was found, but an extremely careful 
search revealed no traces of human agency. 
The two shell beds, as before stated, at the southern side of 
the dock, rest on the gravels, and are separated by silt about 
1 ft. 6 ins. in thickness ; but towards the north, the lower bed 
gradually dies out, and generally there is but one bed on the top 
of the marl over the peat bed, the shells forming a perfect hwer 
on its surface, but in some places penetrating into it as if into 
cracks. This suggests that the clay had been exposed and sun- 
dried before the waters of the estuary formed the shell beach 
which is indicated by the large number of small specimens, and 
the fact that both valves are often intact. The species 
represented were Cardium edule, Tellina solidula, Scrobicularia 
2npe7Xita, Uti-iculus obtusus, Rissoa ulva, Littorina rudis, Littorina 
cbtusata, Mytilus edidis, Pholas Candida, and JVassa incrassata ; 
the five latter have not been recorded before as occurring in 
this bed. The lower bed in places consisted almost entirely of 
Scrobicularia piperata packed closely together. 
Over the shell bed the Humber warp crowns the section, 
but from the centre of the dock, thickening towards the north, 
a laminated sand separates them, the upper part of which 
gradually passes into the warp. The warp itself, formed by the 
alternate rise and fall of the tidal river Humber, is of a grey 
colour, dark when damp and lighter when dry, made up of ex- 
tremely fine layers, each consisting of the sand and mud of a tide, 
the sand of course being heavier and forming the bottom of each 
layer. Although appearances are strongly in favour of this warp 
being largely composed of the boulder clay waste derived from 
