422 
CLARK : GLACIAL SECTIONS. 
the Ouse level (or 50 to 60 feet above that of the sea), but also 
forming extensive low-lands, except close by the river. Where 
these are sandy, and rest on clay, healthy commons still remain, 
such as Tilmire, Langwith, Strensall, and Riccall. 
At present, unfortunately, there are no good sections in the 
glacial beds, but their character can be made out near the New 
Goods Station, at several points round the Mount, especially on 
Holgate Hill, and also at the Poppleton junction of the Harrogate 
and North lines, about two miles out. But, before discussing 
former exposures, it will be best briefly to indicate how the latter 
deposits are related to the boulder clay. 
The chief gravel beds lie on either side of the Ouse, below 
the city. Brick-clays are worked by (1) a low, marshy spot 
called the Foss Islands ; (2) west of Heworth road ; (3) near the 
Poppleton Junction; and (4) on the S.E. edge of the large basin- 
shaped area called Hob- moor. The race course, Knavesmire, lying 
between the two glacial ridges separating Hob -moor from the 
Ouse, is also a brick-earth. 
Peat deposits cover a large area at Askham bog and help to 
fill various small, elevated depressions, such as Campleshon pond 
D, on the Bishopthorpe Road, part of St. Paul's Square C, and a 
patch in Mr. James Backhouse's nursery gardens E ; overlooking 
Hob-moor below Severn's Mount. The last two are concealed by 
Alluvial Deposits, which are about two feet thick at the nurseries. 
Yet here, at the peat surface when a fresh face is exposed, plants 
of the Water Violet, Hottonia palustris, not unfrequently spring 
up. The seed must have laid dormant for ages apparently, for 
not only is there no spot at hand whence it should come, but the 
position in its present state is too dry for favourable development. 
Bones of deer and fragments of a hollowed oak (perhaps a coffin 
or canoe) have been dug out from here. A canoe is possible, as 
there are indications that all Hob-moor may have formed a lake 
at one time. Such, certainly, was the part called Askham Bog 
at the opposite (S.) end, covering an area of 1 J miles by J to J 
