( 253 ) 
It was found, impracticable to transfer to this map the minute delineation of the Yoredale limestones 
which I have performed on the large County Survey, for almost every branch stream of Kibblesdale, 
Airedale, Wliarfedale, Yoredale, Swaledale, Edendale, Garsdale, Dentdale, and part of Teesdale, as 
well as for the whole Penine chain. In the low Craven country, almost all the narrow limestone 
ridges mentioned in the text belong to the Yoredale series, and for this reason are not specially 
marked. The breadth assigned to the lower scar limestone in the anticlinal elevations of Skipton 
and Eothersdale is beyond the truth, but at those points the upper limestones (which belong to the 
Yoredale series) are very closely connected with the lower masses. It must be remembered that the 
shading adopted for millstone grit series includes all the strata between the Y orkshire coal basin 
and the top of the main limestone ; some thin limestones occur in this mass. 
The superficial extent assigned to the Whin sill is very nearly correct ; a part of the range on 
the south side of the Tees assumes somewhat of the aspect of a great dyke ; and if, as I believe, the 
eruptions of basalt have been often repeated in this valley, we may hereafter discover the means of 
distinguishing the products of different ®ras. 
The general absence of igneous rocks on the line of the Penine and Craven faults, at all points 
(except Ingleton) south of the Cross fell region, is a remarkable circumstance, which ought not to be 
forgotten in reasoning on the agencies concerned in producing such disturbances of the strata. 
” Along the line of these faults the usual deposits of calcareous tufa are abundant, particularly on 
the range of the Craven fault : but no sulphureous, remarkably chalybeate, or saline springs, occur 
any where in special connexion with such lines of disruption except about Harrogate. Here, where 
two lines of fault, E. and W. and nearly N., coincide, chalybeate and sulphur springs abound. Farther 
north, at Aldfield near Ripon, on the line of the axis of dislocation which passes E. and W. through 
Greenliow and Brimham, the phenomena of sulphur wells are repeated : and a third case occurs in the 
lower part of Teesdale, at Middleton One How, on the subterranean line of the southern boundary of the 
Durham coalfield, which is also an axis of disturbed strata. It is probable that in each of these in- 
stances the springs derive their sulphureous impregnation from some peculiar action on the shales ot 
the millstone grit series-some of which on a sunny day, by merely rubbing the earth with the hand, 
will disclose the smell of disengaged sulphur. 
The basaltic dykes noticed p. p- 81, 8a, Fryerfold vein in Swaledale and several other veins, some 
anticlinal axes, faults, and remarkable dips, are represented by distinct characters. 
It was found by trial better to engrave characters on the plate than trust to colour for distin- 
guishing the groups. The selection of these characters is not arbitrary, but forms part of a system 
on which much attention has been bestowed, and of which I propose ere long to produce a complete 
specimen and full description, in a Map of the British Isles. 
flUI s. 
(Thomas Wilton and Sons, High- Ouse gate, YoikJ 
