NOTES OX THE GEOLOGY OF CLEVELAND. 
91 
metal too, it appears — the seam assumes such an aspect as might 
deceive many ; since owing to the percolation of water through the 
countless cracks and fissures at its outbreak, the iron has become 
oxidised gradually more and more ; and where not quite oxidised 
throughout, the blocks consist of a nodule in the middle, of nlmost 
unaltered dark blue ore, of nearly equal parts of protoxide of iron 
(about thirty-thi'ee per centum where richest), and peroxide of iron 
(about thirty-two per cent.), and several concentric layers of browm 
ore, the outer of which contains all the iron in a peroxide state, and 
clearly sho^^dng a change to have taken place from a protoxide to a 
hydrated peroxide. In the drift made a httle eastward of the quarry 
we find, after eighty yards of hai'd shale, other eighty yards of the 
altered brown ironstone, with blue nodules, which increase in size as 
we proceed, until at last we reach the solid rock, unaltered by any 
percolation ; intensely hard ; of a blackish-blue colour ; highly mag- 
netic ; lying in horizontal layers ; scarcely fissured, and thirty-two feet 
in thickness. A considerable distance fi'om this drift it has been 
twice bored down to, at a depth of forty -five fathoms, and proved still 
of the same great thickness : although its per centage will probably 
average less than has been given above, there seems no reason to 
fear that the seam will soon be exhausted. Some have thought that 
this rock exhibited symptoms of igneous origin ; others have made it 
out to be affected by heat, subsequently to its deposition ; and some 
have even tried to trace a cause-and-effect — a connection between the 
Whin-dyke, seven miles away, and this astonishing stratum of iron- 
ore. There is however not the slightest foundation for any such 
surmises, as we find it in a horizontal position, in distinct laminae, 
between the upper Lias and sandstone-rock of the Inferior Oolite, — 
most assuredly the natural place of its deposition. The depositing 
waters were greatly impregnated with oxide of iron, which congre- 
gated round any solid object ; and accordingly in each oolitic particle, 
there is some nucleus of shell, sand, &c., which is perceptible under 
the microscope, as in oolitic Hmestones, in the interior of each of the 
grains. There have, I believe, been no organic remains discovered in 
the rock, o^ving, it is possible, to part of the iron being in the peroxide 
state — in which case it is a noticeable fact that there is either very 
great scarcity, or an utter absence of traces of animal life. Whether, 
however, these two facts, so generally coincident, are related as cause 
and effect, is a question for further consideration. The Lias ii-on-seams, 
which contain the iron in a protoxide state only, show the ocean at 
the period of their deposition to have been very prolific in organic 
Hfe. 
An interesting view of this oolitic iron-seam may be obtained by 
tracing its development from Crunkley Ghyl up the eastern side of 
Great Fryup Dale to Fryup Head, and again to its appearance in 
Northdale, on the other side of the moor, and opposite to the great 
iron-quarry of Rosedale, which I have just remarked upon, and 
where, as I observed, the seam appears to attain its maximum thick- 
ness and to possess also its maximum dose of iron. The outbreak of 
