46 
shape under that valley. The southern part of this basin or 
synclinal is found near the village of Acklam, and beyond this, 
from Bishop Wilton to the south of Market Weighton, the 
oolite rocks are lost to view, being hidden under the overlapping 
and unconformable rocks of the Cretaceous series. 
But to the south of Market Weighton, through Cave and 
on to the Humber, the oolite rocks have been upheaved and 
again exposed to the surface, shewing an isolated area of 
Jurassic rocks. 
Particular interest attaches to this area as being situated in 
an intermediate place between the typical Yorkshire and Lin¬ 
colnshire deposits, and it was therefore a most fortunate 
circumstance for geologists when, in the construction of the 
new Hull and Barnsley Eailway, it was found necessary to 
carry the line through the Cave district, cutting through the 
hills and exposing the rocks in a series of sections only second 
in importance to those of the coast. 
As we pass eastward from the low plain of York we meet 
with three successive ridges of land with intervening valleys 
before reaching the chalk wolds. These ridges are formed of 
the liassic, lower oolite, and middle oolite rocks, and their 
structure has been fully displayed by the railway excavations. 
Much of the detail has, however, again become hidden in the 
levelling and grassing of the slopes. The first, or Everthorpe 
cutting is mainly in the liassic series, also exhibiting a good 
section of chalk gravel. 
The lias clay here seen is the ordinary blue clay, containing 
but few fossils; but a species of Ammonites {AEgoceras cajyricomus), 
which was not uncommon, served to determine the exact 
position of the bed, viz : the Capvicornus zone of the middle 
lias. Other beds of the middle lias of an arenaceous character 
next succeed, there being first a soft red clayey sandstone 
(three feet thick), with Amcida inequivalvis^ and then five feet 
of hard brown flaggy sandstone, more or less calcareous. A 
number of fossils occurred here, amongst which are Waldheimia 
resujnnata and Rhynchonella terahedra^ characteristic middle- 
lias species, found especially in the fnargaritatus and spinatus 
zones. Thus we see that the first cutting consists entirely of 
