PHYSIOGRAPHY OF THE EAST RIDING. 21 



of the primeval flora ; for although the channels are chiefly 

 of artificial construction, the aquatic medium is much less 

 likely to bear upon it the impression of man than is the case 

 with land under the hand of the drainer, farmer, and builder. 



From the nature of the rock structure of Holderness, and 

 from the agriculturalist's point of view, the soil is chiefly 

 strong and clayey when directly over the boulder clay, the 

 only exceptions being in the alluvial levels and the gravelly, 

 morainic mounds already referred to. It is not, however, on 

 the whole, the stiff cold land that frequently occurs on the 

 boulder clay in more northerly counties, but is well adapted 

 for wheat growing, pasture, and meadow land, and as such 

 is very well cultivated. Patches of dry, light soil, grow- 

 ing oats, barle)', and mustard, coincide with the morainic 

 accumulations above referred to. 



Where the land lies near the Humber and its affluents 

 there is much natural as well as artificial "warp" or 

 alluvium, which forms rich, fertile soil suitable for root and 

 tuber crops, as well as those of mustard and the legumes 

 (pea, &c.). The many hundreds of acres of reclaimed 

 land known as Sunk Island afford a conspicuous instance. 

 It is interesting to note that in the first stages of natural 

 "warping" or retention of silt, plants of a lowly kind play 

 a very important part in the process. It has been noticed 

 on the foreshore of the Humber at low water that big dark- 

 coloured patches or mounds occur in the mud. On examina- 

 tion of these they are found to consist of an intricate network 

 of the filaments of an alga ( Vaiicheria dichotonui, var. sub- 

 viarina, fide W. West) which, growing with great rapidity, 

 retains particles of mud, seeds, &c., in its meshes, and thus 

 greatly assists in binding together the silt left by the 

 oscillating tide. 



It may be not uninteresting here to give a fuller account 

 of the process of natural warping, or making of new land, 

 just referred to. The process has been carefully studied 

 at Broomfleet, Brough, Hedon, and PauU ; and a notion of 

 it may be gathered from the following : — 



1. The channel of the Humber in man)' places, particularly 

 near the banks, is filled with sand and mud banks, whose 

 presence is indicated not infrequently by a light-ship. These 

 are often the beginnings of new land. 



2. At low water a stretch of muddy foreshore is left. 

 It is on this that the alga (Vaucheria) above mentioned 

 luxuriates, holding the sand and mud together and inter- 

 cepting the fruits and seeds of various plants. Owing to 



