82 
north ; they form a junction in the northern part of the mine, and 
Gategill vein being the older, is displaced about 20 fathoms. 
These veins do not, like the principal veins in the Caldbeck Fells, 
skirt the mountains, and run parallel with the igneous rocks, but 
they pierce both the mountain and the dykes of igneous rock at 
right angles, and probably penetrate the Skiddaw Granite, although 
they cannot be traced into it on the surface. Both of the veins 
contain ore in fair workable quantities on each side of the junction, 
but the twenty fathoms of ground between the points where the 
Gategill vein joins the Woodend vein on the eastern, and leaves it 
on the western side, is the richest portion of the mine. The dykes 
of diorite which are older than the veins, were probably formed at 
the same time as the system of east and west faults, and the diorite 
was consolidated, although the flow of thermal water had probably 
not ceased when Gategill vein fissure was formed and gave fresh 
impetus to it. The thermal action having continued until Gategill 
vein was filled, a fresh disturbance took place, Woodend vein fissure 
was formed, and the thermal action again revived, and continued 
in operation until the new fissure was filled. Thus, the deposition 
of ore between the points of junction, would continue double the 
length of time that it was in operation in other portions of the 
veins, the junction being re-opened, and becoming part of Woodend 
vein, as it had previously been of Gategill vein. 
A remarkable feature in these veins, is the small quantity of 
quartz associated with the ores, donk being a more prominent 
concomitant; but they contain, in addition to the ores of lead and 
zinc, a great deal of iron pyrites, which is undergoing decomposition 
at a rapid rate, the water flowing from some parts of the mine being 
highly charged with oxide of iron in solution. A deposit of 
limonite formed by this mineralized water in the low level at Wood- 
end (now Threlkeld) mine, is described in a paper on “ Mineral 
Springs near Keswick.”* 
A decomposition similar to the one in progress at Threlkeld 
mine was completed long ago in some of the neighbouring veins. 
The large vein at Saddleback Old Mine, in the Glenderamakin 
* Trans. Cumb, and West. Assoc., No. xi. p. 142. 
