256 GILLIGAN : ALLUVIAL DEPOSITS AT WOODLESFORD, ETC. 
{b) Space for the laying out of extensive sidings for full and 
empty trucks, and for the surface buildings and equipment. 
(c) Drainage of all surface waters and of the water wliicli may 
possibly be met with underground. 
[d] Ease or difficulty of sinking the shafts due to water, faults, and 
subsidence caused by old workings, etc. 
After due consideration of these points a site between the railway 
and the canal, exactly across the railway from the site finally selected, 
was more closely examined. This gives ready access to both railway 
and canal, but it was found unsuitable as not affording space for siding 
accommodation, and it would further have necessitated the formation of 
very high railway embankments to deal with the coal by gravitation, 
and to effect a railway connexion with the main line. On the south 
west side of the railway, however, is a flat tract of ground bounded on 
the river side by the 50 ft. contour, and marked as Second River 
Terrace gravel on the geological maps. This stands about 20 feet 
above the ground first selected on the other side of the river, which is 
the First River Terrace. A section taken across the valley at right 
angles to the railway is like a shallow saucer with the canal and river at 
the lowest point. The embankment which carries the Midland Railway 
passes down the centre, and to approach this height at ground level it 
is necessary to work from the Second River Terrace. 
The next question was whether much difficulty would be experi- 
enced in sinking the shafts for the colliery through the alluvium. Ob- 
viously at any point low down near the axis of the valley there would 
be much water in the alluvium to contend with, and there was justifiable 
hope that at any point away from the axis the alluvium would be thinner 
as a consequence of the slope of the old valley before it was infilled. 
This slope would determine the direction of flow of the ground-water, 
whereas the direction of flow of the surface-waters is, of course, deter- 
mined by the present outline of the surface. Away from the axis, 
therefore, the alluvium tends to be less water-logged than nearer the 
centre. 
Next, with regard to subsidences caused by old underground 
workings. The workings in the Haigh Moor seam — at a depth here 
of noly 67 yards — extend from Spencer Colliery almost to the Midland 
