HOLDERNESS. 
25 
Alluvium. — The alterations in the form of land, occasioned by 
diluvial agency, must have been considerable, but are not yet well 
understood ; the operation of natural causes since that period, de- 
serves to be maturely considered, for these have materially changed the 
face of the globe. The lakes, which were left on the retiring of the 
diluvial currents, appear to have been continually diminished in depth, 
and contracted in extent, by deposits of vegetable matter, decayed 
shells, and sediment brought into them by land-floods. In this manner 
many inland lakes have been extinguished in Holderness, and nothing 
remains to denote their former existence, but the deposits by which they 
have been filled. It is remarkable that the observers of this coast 
have bestowed very little attention on the lacustrine deposits which 
appear so frequently on the cliffs, and exhibit, so convincingly, the 
proof of long-elapsed time since the date of the fundamental diluvial 
formation. To amend, in some degree, this defect, I propose to de- 
scribe them pretty minutely in my observations on the section ; but 
it will be desirable to sketch a general outline of their characters here, 
and to put them in comparison with the contemporaneous marine de- 
posits, which are so remarkable on the shores of the Humber. 
All the lacustrine deposits containing peat, which I have inspected 
in Holderness, agree in this general fact, that the peat does not rest 
immediately upon the diluvial formation beneath, but is separated from 
it by at least one layer of sediment, which is seldom without shells. 
The peat is very generally confined to a single layer, and shells are 
seldom found above it. Supposing that all the varieties which I have 
witnessed in different places existed together, the section would be 
nearly in the following general terms : 
1 Clay, generally of a blue colour, and line texture. 
2 Peat, with various roots, and plants, and, in large deposits, containing abundance 
of trees, nuts, horns of deer, bones of oxen, &c. 
3 Clay, of different colours, with fresh- water limnese. 
4 Peat, as above. 
5 Clay, with fresh-water cyclades, &c. and blue phosphate of iron. 
6 Shaly curled bituminous clay. 
7 Sandy coarse laminated clay, filling hollows in the diluvial formation. 
E 
