54 
has also its value in tlie commercial world as well as to the 
geologist and to the chemist. This rock of Pontefract is the 
geological problem of the neighbourhood, and which is by no 
means solved. The facts at present known seem to show 
that it rests in some places unconformably on the upper beds 
of the coal measures, and that this sandstone rock was laid 
down upon the edges of the previously formed strata, so that 
this lower sandstone overlaps sometimes upon one layer and 
sometimes on another in tumultuous confusion, as may be 
seen at Glass Houghton, upon the carboniferous rocks. 
From the different quarries between Darrington and Glass 
Houghton, 31,000 tons of this sandstone rock are annually 
excavated and sent to all parts of the country for use at the 
different iron foundries for moulding castings. 
Darrington and Pontefract 840 
Monkhm 17,640 
Glass Houghton 12,520 
Total Tons 31,000 
These sand quarries are full of the bones of extinct animals, 
and the sand, from chemical analysis, would appear to owe 
its origin to the action of fresh water, as under : — 
Mill Hill Eock. 
Carbonate of Lime 1*00 
,, Magnesia '55 
Sesqui-oxide of Iron 1'78 
Alumina (soluble in acid) '72 
Insoluble Residue (Siliceous 
Sand) 94-42 
Moisture, &c 1'53 
100-00 
Monk Hill Eock. 
( Bos Longifrons. ) 
Carbonate of Lime 4*46 
„ Magnesia 2-89 
Sesqui-oxide of Iron 2*33 
Alumina (soluble in acid) 4-12 
Insoluble Eesidue (Siliceous 
Sand) 83-60 
Moisture, &c 2-60 
100-00 
BOS LONGIFRONS. 
It was on the 29th of April, 1869, while some men were 
excavating this sand at Monkhill, that the bones of an 
animal were exhumed. At a depth of about twelve feet 
from the surface of the ground they saw what appeared to be 
