Lign. 275. Ideal transverse Section of Crich Hill.
| A, A.— | Highly inclined strata of Millstone Grit. |
| B, B.— | Arched strata of Mountain Limestone. |
| C.— | A central nucleus of Trap or Toadstone. |
To a mind accustomed to investigations of this nature, a slight examination of the phenomena under review will, I apprehend, suffice to demonstrate the correctness of these deductions; but I may have failed to place the subject before the general reader in an intelligible and lucid point of view; should this be the case, still, if the attempt to present a familiar exposition of the physical structure of this remarkable district shall induce him to visit the scenes I have so imperfectly portrayed, and interrogate Nature in a right spirit, the hours we have passed together in our excursion to Crich Hill will not have been spent in vain; for in the beautiful language of the noble bard:—
"To sit on rocks, to muse o’er flood and fell,
To slowly trace the forest’s shady scene,
Where things that own not man’s dominion dwell,
And mortal foot hath ne’er or rarely been;
To climb the trackless mountain all unseen,
With the wild flock that never needs a fold;
Alone o’er steeps and foaming falls to lean;
This is not solitude; ’tis but to hold
Converse with Nature’s charms, and view her stores
unroll’d."—Childe Harold, Canto II. xxv.
Specimens of Fossils and Minerals.—On our return, our first care must be to look over all the specimens we have gathered, arrange them, and select those which are the most illustrative of the phenomena we have examined; and ticket every specimen, as recommended in the Instructions. The fossils, consisting of several species of spirifer and other brachiopoda, and of portions of encrinital stems, require no particular care. The rocks should comprise specimens of the different varieties of limestone and sandstone; and of the green limestone, altered by contact with the toadstone; and examples of the compact trap, and of the variety veined with red jasper,—of the amygdaloidal toadstone,—and the vesicular, or that in which the cavities are empty. The minerals should comprise the ores of lead, zinc, barytes, fluor, and calcareous spar; of the last some good clear pieces should be selected, that will exhibit its double refracting property. Of the common metal, Pyrites, a few specimens should be preserved; this mineral, from its splendid yellow appearance, is often mistaken for gold; but a mere blow of the hammer will immediately detect it, for Pyrites is brittle, and readily cracks to pieces, while gold, as is well known, is remarkably ductile. If the collector be not satisfied with the fruits of his day’s researches, he should look over the catalogue of Mr. Adams, and purchase such specimens as will render his collection sufficiently extensive to present a full illustration of the geological character of the scenes he has this day visited.
There is a variety of sulphate of barytes from near Youlgreave exhibited in the shops at Matlock, of which one or two examples should be obtained. The surface of the polished specimens much resembles the rich variegated appearance of dark tortoise-shell. This mineral has been formed, like the common calcareous stalactite, by infiltration through some porous rock; transverse sections exhibit concentric layers of various shades; while the longitudinal have the varied colours disposed like those in tortoise-shell.
BONSAL VALLEY.