170 REPORT—1858. 
line, that is, when Gritstone on one side of the vein is opposed to Plate on 
the other, and Limestone to Gritstone, or Limestone to Shale, the veins are 
not often found productive of Lead ores. There are, however, many ex- 
ceptions to this rule. At the Grassington Mines are two parallel veins, 
within 80 fathoms of each other, both throwing the south side down to such 
an extent, as to cause Plate to be opposed to Gritstone, Plate to Limestone, 
and Gritstone to Limestone, and so on throughout the whole depth explored 
on them. (See fig. 5.) So circumstanced, one of these veins yielded great 
abundance of ore, while the other proved to be totally barren. 
We often find, when the vein occasions a throw of some two or three 
fathoms, that the ore does not extend above the change of strata on the 
hanging side, nor below the change on the lying or footwall ; for instance, 
when the bed of Grit or Limestone is 10 fathoms thick, and the throw of 
the strata is 3 fathoms, we have only 7 fathoms in height of ore; but in 
some cases the ore is found to extend the full thickness of the bed with the 
addition of the extent of the throw. Diagram 4 represents a transverse sec- 
tion of such a vein in the Grassington Mines, from which considerable quan- 
tities of ore are now being raised. 
The strata on each side of a vein are not only at different levels, but near 
the vein they have a different position, being bent upwards on the one side 
and downwards on the other. As a rule, the strata on the higher side are 
bent downwards to the vein, and on the depressed side from it. Thus, if 
in driving a crosscut southward, in search of a vein ranging east and west, 
we arrive at a point where the beds assume a faster dip, our approach to a 
vein that throws the strata down on the south side, is inferred; while, if in 
driving northward, the beds curve quickly upwards, we anticipate a vein 
with the north-side strata at a higher level. (See fig. 5.) 
In each of our Lead-bearing districts, the strata consist of numerous 
alternating beds of Plate, Gritstone, and Limestone; forming the Yoredale 
Rocks of Professor Phillips. 
The veins are found to traverse or pass through all these beds, but gene- 
rally speaking, it is only in certain of them that Lead ore is found; the 
Limestone being the prevalently productive stratum in some districts, whilst 
in others the principal yield of ore is from the Gritstone. The Argillaceous 
Plates seldom yield ore; but there is an exception to this in the Cononley 
Mines, where bunches of ore have continued from the surface, to a depth 
of more than 30 fathoms; although the alternations of Plates and Gritstones 
are exceedingly numerous, and the Plates much thicker than the Gritstone 
beds. 
From these facts it follows, that a rule, by which to calculate on metallic 
products from certain rocks, will not admit of general application; but we 
may carry it so far as to say, that in a given district, certain beds generally 
are, and others generally are not, productive. 
Many veins, particularly in our more Northern fields, preserve a tolerably 
direct course for a considerable distance. The Old Gang Vein in Swaledale, 
for instance, has been worked for several miles in length, and can be traced 
to a much greater distance in nearly a straight line. 
In our three Northern Mining Fields,—Swaledale, Arkendale, and Wens- 
leydale—the veins appear to be more regular in size and direction, and the 
beds preserve a more uniform thickness, than in the three Southern Fields. 
In the former, likewise, the calcareous beds have been the principal sources 
of produce; whereas, in our Southern ones, the greater portion of the ore 
has been, and still is being produced, from the Gritstone. 
There are other causes by which the productiveness of the veins appear 
