belongs to the Wirral Colliery Company, and the coal-seams are 
actually worked under the estuary of the River Dee. This com- 
pany is now boring in search of coal on the shore at high-water 
mark opposite Denhall, near Burton Point Railway Station. On 
12th October, 1901, the depth reached was 250 feet, without 
finding coal of workable thickness. Two thin seams of coal of 
about two inches each were passed through in the boring, and it is 
likely, owing to numerous faults in the strata of the locality, that 
workable coal may not be discovered. The writer is much 
indebted to Mr. James Platt, manager of the Wirral Colliery, and 
to his sons, Mr. William and Mr. Walter Platt, for much valuable 
information in connection with the working of the coal-seams in 
this interesting district, more especially on the occasion of a recent 
visit made by the members of the Liverpool Geological Society, 
under the leadership of the writer, to this boring, and also to the 
coal-pit. 
On the Flintshire side of the estuary of the Dee the Middle 
Coal-measures extend for several miles, and at Mostyn Colliery, 
which is now full of water, the Middle Coal-measures have been 
worked for a distance of a mile under the bed of the river. 
At the Point of Air a bed of coal is being worked at the 
present time at the West Mcstyn Colliery. This is the most 
northern part of the North Wales Coalfield. A boring in search of 
coal was recently made at Bidston Railway Station, when a depth 
of 2,850 feet is said to have been reached without coming to coal. 
The Upper Coal-measures are not regarded as being of much 
commercial value, as they do not produce coal-seams of sufficient 
thickness to be workable. The nearest Coal-measure strata 
to Liverpool are at Croxteth, and belong to this subdivision. 
Exposures may also be seen in the neighbourhood of Rainhill, 
Whiston and St. Helens. The Permian strata are not exposed in 
any outcrops within the area, and their presence is regarded as 
rather doubtful by geologists. 
The following are the subdivisions of the Triassic System, 
which is developed to such a large extent in the neighbourhood of 
Liverpool : — 
( Keuper- 
Keuper Marl. 
( Keuper Sandstone. 
Trias / Upper Bunter Sandstone. 
( Bunter Pebble- beds. 
(Lower Bunter Sandstone. 
