DURNFORD : DEEP BORING NEAR SELBY. 
339 
In settling the site for the borehole more weight was attached 
to position from a geographical standpoint with proper access 
to the river and railways crossing the property than to the best 
position geologically. In fact, as little or no reliable information 
was available, it would have been difficult to decide on any 
other grounds. 
Professor Kendall has very kindly lent a map showing 
the boundary of the Yorkshire and Nottinghamshire Coalfield 
as suggested by various authorities from time to time. The 
brown line is the limit as suggested by the late Professor Green 
before the 1871 Commission, the outer blue line as suggested 
by Professor Hull, and the red line as suggested by Professor 
Kendall in his report to the Royal Commission of 1905. From 
this map it will be seen that although the site of the hole was 
chosen as far south as the boundaries of the estate would permit, 
it was not very far from the supposed northern limit, being 
in fact almost on Professor Green's line, two miles south of 
Professor Hull's, and seven miles south of Professor Kendall's. 
Turning now to the consideration of the strata passed 
through, the first 75 feet proved to be alluvial sands, gravels, 
and clays. Beneath this superficial deposit the Triassic Rocks 
were met with — presumably the Bunter Beds. Whether the 
Keuper Beds exist at Barlow or not appears to be an open 
question. Those passed through, however, consisted of coarse 
red and occasional grey sandstones presenting no features 
of particular interest until at a depth of 690 feet a series of marls 
and gypsum bands was entered, which proved to be about 
120 feet in thickness. The Bunter Pebble Beds, so well developed 
in Cheshire and Shropshire, were very meagrely represented, if 
at all. In the absence of fossil evidence it is difficult to decide 
whether the series of marls referred to belongs to the Permian 
or the Trias. It would appear probable that it belongs partly 
to both divisions, and that no definite horizon can be taken 
as the transition from Permian to Trias, but that the one merges 
into the other. Beds of red marl constituted the first 50 feet 
of the series, being followed by beds of gypsum and anhydrite. 
These beds of anhydrite are very persistent throughout the 
district, and were proved in borings at Snaith, Thome, and 
