|
_a_ |
|
+------ 4'
|
_b_ |
+------ 7'
|
_c_ |
+------ 10'
_d_ |
+------ 12' 6"
_e_ |
+------ 13' 2"
|
|
|
_f_ |
|
|
|
+------ 21' 2"
_g_ |
+------ 23' 2"
_h_ |
|
_a._ Dark clay, with much carbonaceous matter, scattered
stones, and freshwater shells 4' 0"
_b._ Tough clay 3' 0"
_c._ Dark clay full of bits of wood 3' 0"
_d._ Light coloured clay full of rootlets 2' 6"
_e._ Rusty sand 8"
_f._ False bedded gravel and sand pierced by rootlets 8' 0"
_g._ Black silt and gravel 2' 0"
------
_h._ Gault 23' 2"
======
[Illustration: Fig. 3. Section seen in Bullock's Pit in S.E. corner of
Midsummer Common.]
It will be noticed that there is very little peat here and all of it
was below O.D. The upper four feet of the clayey peat (_f_) looked as
if the vegetable matter had been transported, perhaps from peat beds
being destroyed by the river higher up, and been carried down in flood
with the clay, while the lower four feet of peat (_h_) was only a
cleaner sample of the same, before the river had cut down into the
clay. The trees in both _f_ and _h_ were not trees that had grown on
the spot and had been blown down, but were broken, water-worn, and
evidently transported.
_a_ +-----------------
_b_ +-----------------
_c_ +-----------------
_d_ +-----------------
_e_ +-----------------
|
_f_ |················· _g_
|
+-----------------
|
_h_ |
|
+----------(1)----
_i_ |
+-----------------
|
_j_ |
|
+----------(2)----
_a._ Surface soil 7"
_b._ Clayey alluvium 7"
_c._ Peaty alluvium 9"
_d._ Brown clayey alluvium 1' 6"
_e._ Peaty alluvium. 9"
_f._ Brown clayey peat with trees scattered throughout
_g._ and lenticular beds of freshwater shells in it 4'
_h._ Peat with trees to 2' diam. 4'
_i._ Mottled green and grey clay with lines of sand and
gravel giving out water 2'
_j._ Yellow clay with springs and much rusty water
at bottom. 4'
------
18' 2"
======
(1) Skull and a few other bones of horse.
(2) Broken fragments of bone.
_Scale_ 8' to 1"
[Illustration: Fig. 4. Section seen in pit dug for material for making
up the roadway east of the new bridge over the Ouse by the railway
station. Ely, 1910.]
If now we travel about 30 miles a little west of north we shall arrive
near the shore of the Wash about half way across its southern coast
line at Sutton Bridge. Here I had an opportunity of seeing the material
of which the alluvium is composed. With a view to securing a sound base
for the foundation of the piers of the Midland and Great Northern
Railway bridge an excavation was made through the whole of the Fen Beds
down to the Boulder Clay which as I have already stated was reached at
a depth of 73 feet. The clerk of the works kindly gave me the following
measurements (Fig. 5).