92 
THE GEOLOGIST. 
the seam has, owing to the decomposition of the iron, a recldish- 
broNvn appearance ; and, where sufficiently rich in iron, shows the 
usual " scrappy" layers, or envelopes, owing to the percolation of 
water. This is very noticeable at Fryup Head, where the seam is of 
great thickness. 
I now pass upward to the "bottom sandstone rock," of which I spoke 
before, and which is the great and safest guide in searching for the iron- 
stone strata. It runs along the summits of the sides of most of the 
Cleveland dales, and has been used very generally in the district 
for building purposes. At Sleights, near Whitby, it has been exten- 
sively wrought for local use, as also for shipment, and is in fact the 
great building stone for the whole of Cleveland. It caps most of the 
chief hiUs, or " banks," as they are called in the district, crowning the 
summit of Roseberry Topping, Easby Bank, &c. The excellent state 
of preservation of the stonework in the ruins of Guisborough Abbey, 
and Mount Grace Priory, attests the dm-ability of the rock. 
I now come to the next division in my section (/), which it would 
be difficult to subdivide in such a manner as to be equally applicable 
to all parts, where the rocks contained in it crop out to view. Above 
the bottom sandstone rock, however, are aliernations of shales, thin 
iron-bands, and gi'itty sandstone layers, about sixty feet in total thick- 
ness. We then come to a vast series of sandstones and shales of 
various colours and thicknesses, and amongst them are some seams 
which demand a short notice. In this series we find a variable stratum 
of fire-clay, which is well seen in the excavations of a recently-fonned 
Fire-clay Company at Skelderskew, in Commondale, where it is of 
considerable thickness, and, it is also stated, of great commercial 
value. Embedded in an impure sandstone bed above this seam are 
found vertical Equisetites, in great abundance — the Equisetum colum- 
nare. Higher up, amidst the countless beds of shale and sandstone, 
we find a thin seam of coal, of sufficient importance however to be 
worked for local use, although the thickness is never more, and some- 
times a few inches less, than sixteen inches. This seam, which is 
accompanied by fossil plants in the shales above and below, is similar 
to one discovered in the same oolitic series of Brora, in Scotland, and 
worked from the patriotic — certainly not pecuniary — motives of a late 
Duke of Sutherland. In the isorth Yorkshii^e district it is worked 
at Rosedale Head, Danby End, and, until recently, at Great Fryup 
Head. It may be seen out to the day on the side" of the road from 
Castleton to Guisborough, about half a mile from the former place ; 
and in the hill as you ascend to Danby Beacon from Howlsike. An 
acre of this moor-coal is generally estimated to contain about two 
thousand chaldrons of thirty-two bushels. The appearance of this 
carboniferous deposit has not failed to excite hopes in some whose 
scientific knowledge, it need hardly be said, is Like the coal-seam- 
limited : that by going further down, better, or — as some even think 
— the Durham coal-seams will be discovered. Although men seem 
bom with the only-go- deeper" notion in their heads, it seems un- 
necessaiy to remark, that any hopes of finding coal superior to that 
