94 
THE GEOLOGIST. 
and its only visible effect is the charring of the coal, which it divides 
in Durham, and the ordinary results of intense heat upon the con- 
tiguous shales, limestones, and sandstones. Its width is from 
seventeen to alDOut sixty feet, and is greater in the middle than at 
its two extremities. Its depth, it need not be added, is unfathonable. 
When unaltered by weather it is of a dark blue colour ; but owing to 
the iron which it contains, the outer portion becomes rusted upon 
exposure, and exfoHates like an ironstone. An excellent view of this 
"frolic of nature," as it has been called, may be seen in a cutting 
which the railway has made through it near Castleton, and its caustic 
effects on the bordering strata for a very short space on each side, and 
total absence of dislocating fracture may be clearly obsei-ved. Owing 
to its intense hardness, it is of invaluable utility as a material 
for the roads to a gTeat distance on each side of it, for which it would 
otherwise be a difficulty to find a stone sufficiently durable. It is, 
and when the proposed lines are completed will be much more, exten- 
sively wrought, and sent to a great distance to pave the streets of 
several of our large towns. 
There are many instances of alluvial deposits, and many isolated 
granitic boulders at the foot of Carlton Bank, at Lealholme Bridge, 
and other places, which I cannot now stay to remark upon. With 
reference to the vast superficial accumulations of peat at Danby End 
and other places, I shall quote an extract from a work published 
about eighty years ago,* as an illustration of a geological theory 
at that period, and at the same time to impart a piece of interesting 
information for any " Judasus Apella" of the nineteenth century : 
" Hazel-trees and nuts with kernels in them are found in our peat- 
bogs, covered up most probably by the deluge ; and I cannot help 
observing here, that these nuts prove to a demonstration that the 
flood of ISToah happened in the autumnal season of the year, and 
most probrably in the month of September, when it is known that 
kind of fruit is always ripe with us here in Yorkshii^e." 
I may here observe before, before I conclude, that there are traces 
to be noticed, at Furnace Farm, near Fryiip End, in Commondale, at 
Castleton, and other places, of the rude manufacture of iron in 
ancient times. At the above places are large heaps of scoriae, from 
which the metal has been but imperfectly extracted, and amongst 
which I have found pieces of the metal itself. These primitive iron- 
masters, who lived most probably in monkish times, seem fi-om the 
small pieces of ore which I have found to have merely collected the 
loose boulders; or outside pieces of the thin rich nodular bands, and, 
of course, used charcoal only, as may abundantly be seen, in their 
reduction to a fluid state. 
It now merely remains for me to express my regret at not being 
able within the scope of this essay to dwell, as I should gTeatly have 
wished, upon the characteristic and other fossil-remains of the 
several groups ; and to express the obhgation I am under to the 
* Hist, of Whitby by L. Charlton : 1779, p. 353. 
