56 
is by examining the junction. If the country were mapped, and 
a fault affecting other strata traced through the pit, this would 
settle the question in favour of a fault. There seem to be 
disturbances in the neighbourhood. We have Oxford clay, 
for instance’, at the bottom of the hill near the railway station, 
where Kimmeridge clay would have been more natural. And 
other places might be named (Aldreth and Alderforth). But 
that faults affect the oolites affords only a slight presumption 
that they will also affect the boulder clay. With regard to the 
evidence to be obtained at the spot itself, I first of all attempted 
to examine the junction by digging in the side of the pit; but 
I found that, owing to a line of springs thrown out by it, the 
boulder clay has slipped, so that I could not reach the undis- 
turbed ground. This circumstance misled me when I examined 
the place in 1856, and made me suppose the junction showed 
slickenslide, which was really due only to a recent slip. I then 
searched for and found the junction in one of the banks left by 
the workmen to exclude the water as they dig. 
Here I found it well defined, but I could not discover any 
of those symptoms of pressure, or the polished surfaces, which 
are always observed to accompany a fault. As far then as the 
evidence goes it is against the occurrence of a fault, and points 
to the boulder clay occupying a trough, which it has ploughed 
out for itself in the old sea bottom of Kimmeridge clay. Such 
troughs I believe to be not uncommon in districts bordering 
upon extensive spreads of the boulder clay. 
I have made diagrams of sections seen in two boulder clay 
pits at Gillingham in Norfolk, and at Bulchamp in Suffolk, 
which illustrate the manner in which the sea bottom has been 
eroded by icebergs, and the cavities filled with boulder clay. 
In the instance at Bulchamp, which I saw with Professor 
Liveing last summer, the sea bottom has consisted of a sand, 
1 T have since learned, however, that a well at Ely commenced in the Kim- 
meridge soon reached the Oxford clay with a thin stony band containing Nerinea 
intervening. 
