223 
marshy deposit is perhaps the source from which the ore 
was obtained. In some of the marsh-land ditches a copious 
white flocculent deposit is formed, the nature of which 
I have not yet made out. 
5. Peat and Forest Bed. — Over the lower part of the 
area of the Yale of York there extends a bed of Peat, resting 
sometimes directly on the clay, at other times on a thin layer 
of water-logged sand above the clay. On Thorne "Waste this 
Peat bed attains the depth of 20 feet, but as we approach the 
older cultivated lands it becomes much reduced in thickness ; 
at Groole being only six inches thick. This thinning out is 
due partly to the shorter time during which it has been form- 
• ing, the formation of Peat being put a stop to when the land 
was warped, partly to the compression which the peat has 
undergone by the weight of the overlying soil. The mere act 
of cutting a drain through the Peat causes it to collapse, for, 
although the Peat is almost as impervious as Clay, yet the 
water, which it holds like a sponge, gradually drains away, 
and the Peat then shrinks. It is said that points in the land- 
scape are now visible across the moor which formerly were 
hidden, owing to the shrinking of the drained land. It is 
only where the surface of the sand lies low that we get any 
considerable development of Peat ; where it is elevated above 
the tide level, the Peat is either absent or represented only 
by black vegetable mould, mixed with Sand. 
At the very bottom of the Peat, and rooted into the 
Sand (as shown in Fig. 2), are the stumps of innumerable 
trees, many of large size ; the majority of them are Scotch 
fir, but oak, willow, birch, hazel, and other trees are also 
met with. The leaves and fruit of the cranberry are 
found, and the remains of other plants now living on the 
moors may be recognised. Elytra of beetles and other insect 
remains are common, but these are the only relics of animals 
that I have seen ; horns of deer are, however, found ; I am 
