Goniatites Listeri, S. Mus.G., P., Looney, 40-42. Goniatites cyclolobus, P. Mus, G. The

Concerning No. 5, it may be necessary to observe that the sloping line marks the plane of a fault inclined at a small angle to the horizon, while the beds which are shifted by it dip steeply in the same direction. If we suppose these beds turned again nearly level (let the book be turned round 90°,) the fault will then be found to follow the ordinary laws of displacement (page 118.) This is the only case I have ever seen of an uplifted mass of previously dislocated strata, (producing an apparently horizontal fault.) In No. 6, the dark part is the vein; the shaded parts on each side the altered rock. In Nos. 9, 10, the dark parts are chiefly shale, the white parts limestone, the obliquely shaded parts coarse gritstone.

The three long Sections are sufficiently intelligible, without farther remark, than that they are drawn to a scale of 3000 feet elevation in one inch: the dark part (in No. 1,) is the coal formation: over it is a small extent of new red sandstone and magnesian conglomerate; the dotted part millstone grit series, (the strongest dotting shews particular grit rocks); the white parts are limestone; the shaded parts shale and gritstone; the vertical lines mark the grauwacke basis of the Penine region. In tracing the edges of the different limestones of the Yoredale series round the hill sides, the geologist is greatly assisted by a peculiarity of the drainage, arising from the contrast between the pervious limestone and the watertight grits and shales. It is almost an invariable character of these limestones on sloping ground, to be marked along, or rather a little above, their surfaces by a series of round hollows, or deep pits, which gather the water from the shaly surface, and suffer it to pass downward and to issue at some lower point in a spring. In all the northern and western dales of Yorkshire the five principal Yoredale limestones, and sometimes also the thinner beds between them, are marked on the surface by parallel ranges of such swallow holes," and pits, often shewing the peculiar corrosion of acidulated water. The phenomenon is generally independent of disturbed stratification; and in fact is chiefly the result of atmospheric action and rain, on the jointed calcareous rocks. The diagrams Nos. 14 to 19, are sufficiently explained in the text. 20. Gordale is in lower scar limestone. 21. Outline of Ingleborough: the top is lower millstone grit: the prominent ledge below is main limestone, the next prominent ledge is a thick sandstone, and from this to the limestone floor, which is the basis of the mountain, the steep slopes are formed principally of shale (with thin limestones and gritstones.) 22. Part of Brimham rocks the upper millstone grit. 23. In this sketch of part of Craven the smooth outlines and insular hills are formed of shale, and thin limestones; the dark rougher ground is millstone grit. 24. Must be studied by referring to the text of Chap. vi. p. 176. It is principally intended to call attention to the important fact that the local origin of the limestones is different from that of the sandstones and shales; the former arriving at a maximum thickness in the S. E.-the latter in the N. W.

Plate XXV.-The Geological Map.

This map contains nothing conjectural; it is wholly drawn from personal observation, except a small part of the range of magnesian limestone near Markington, which I have taken from Professor Sedgwick, (Geological Transactions) and the outline of the small coalfield of Ingleton, which was given me by Mr. Hodgson. Almost every part is minutely correct; a small portion about the head of Lunedale, and the new red sandstone and magnesian limestone tracts near Ingleton and Kirby Stephen, excepted, (where it is almost impossible for accuracy to be obtained.)

It was found impracticable to transfer to this map the minute delineation of the Yoredale limestones which I have performed on the large County Survey, for almost every branch stream of Ribblesdale, Airedale, Wharfedale, Yoredale, Swaledale, Edendale, Garsdale, Dentdale, and part of Teesdale, as well as for the whole Penine chain. In the low Craven country, almost all the narrow limestone ridges mentioned in the text belong to the Yoredale series, and for this reason are not specially marked. The breadth assigned to the lower scar limestone in the anticlinal elevations of Skipton and Lothersdale is beyond the truth, but at those points the upper limestones (which belong to the Yoredale series) are very closely connected with the lower masses. It must be remembered that the shading adopted for millstone grit series includes all the strata between the Yorkshire coal basin and the top of the main limestone; some thin limestones occur in this mass..

The superficial extent assigned to the Whin sill is very nearly correct; a part of the range on the south side of the Tees assumes somewhat of the aspect of a great dyke; and if, as I believe, the eruptions of basalt have been often repeated in this valley, we may hereafter discover the means of distinguishing the products of different æras.

The general absence of igneous rocks on the line of the Penine and Craven faults, at all points (except Ingleton) south of the Cross fell region, is a remarkable circumstance, which ought not to be forgotten in reasoning on the agencies concerned in producing such disturbances of the strata.

Along the line of these faults the usual deposits of calcareous tufa are abundant, particularly on the range of the Craven fault: but no sulphureous, remarkably chalybeate, or saline springs, occur any where in special connexion with such lines of disruption except about Harrogate. Here, where two lines of fault, E. and W. and nearly N., coincide, chalybeate and sulphur springs abound. Farther north, at Aldfield near Ripon, on the line of the axis of dislocation which passes E. and W. through Greenhow and Brimham, the phenomena of sulphur wells are repeated and a third case occurs in the lower part of Teesdale, at Middleton One Row, on the subterranean line of the southern boundary of the Durham coalfield, which is also an axis of disturbed strata. It is probable that in each of these in stances the springs derive their sulphureous impregnation from some peculiar action on the shales of the millstone grit series-some of which on a sunny day, by merely rubbing the earth with the hand, will disclose the smell of disengaged sulphur.

The basaltic dykes noticed p. p. 81, 82, Fryerfold vein in Swaledale and several other veins, some anticlinal axes, faults, and remarkable dips, are represented by distinct characters.

It was found by trial better to engrave characters on the plate than trust to colour for distinguishing the groups. The selection of these characters is not arbitrary, but forms part of a system on which much attention has been bestowed, and of which I propose ere long to produce a complete specimen and full description, in a Map of the British Isles,

FINIS.

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(Thomas Wilson and Sons, High-Ousegate, York.)

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