Imágenes de páginas


Series of Yorkshire strata. Geological

Geological description of the eastern part of the county.

Yorkshire is one of the few counties of England, which are, for the most part, defined by natural boundaries. On the west it reaches, and in some places extends beyond, the great summit ridge of the island ; it has the Tees as its natural limit on the north, the Dun for a great length on the south, and on the east is washed by the German ocean. Its area is divided into several obvious sections, distinguished alike by topographical features and geological structure. Along the middle of the county, from north to south, runs a wide level vale, filled with gravel, deposited on the upper red sandstone. From beneath, rises towards the west an elevated undulated tract, of carboniferous and calcareous rocks, which ascend to the summits of Micklefell, Ingleborough, and Pendle Hill; whilst above, on the east, appear the uniform ranges of the chalk and oolite. The hilly western tract is grouped in two portions : the district south of the Aire, in which, generally, sandstones and shales with coal abound; and the more elevated region north of that river, whose romantic dales are sunk into the mountain limestone, and whose hills are capped by the lower members of the coal series.

The eastern part of Yorkshire may be topographically considered in five divisions.—Three of these are conspicuous from their elevation ; viz. the open round-fronted wolds of chalk in the south, the flat-topped ranges of oolite in the middle, and the more mountainous groups of shale, sandstone, limestone, and coal, which form the northern moorlands; two are wide, level tracts : viz. the vale of Pickering, which separates the chalk wolds from the oclitic lills, and Holderness, which is a broad tract of alluvial marshland, undulated by hills of diluvial clay and gravel.

These five divisions of the surface reach the coast in succession, and mark it with very characteristic features. The shore of Holderness is, like the interior, low and undulated; the wolds terminate in long, lofty, and connected cliffs; a depression on the coast marks the line of the vale of Pickering ; flat-topped heights characterise the oolitic formation on the shore, as well as in the interior ; and the highest precipices on the coast belong to the same series of rocks as the loftiest of the inland hills. It will, therefore, be no unprofitable labour to attempt a connected sketch of the geological characters of the five districts, into which nature has divided the eastern part of this county, before we describe, in greater detail, the sections which they present against the sea. however, necessary previously to exhibit a

It is,



[ocr errors]

utmost thickness.

fect. 11 White Chalk 500 The Wold hills from Chalk formation.

2 Red Chalk

5 5 Flamborough to Hessle. 3 Gault?

Speeton, Knapton. Clay vale formation.

150? | Kirby-Moorside, Helms(Smith)

ley, Settrington, El4 Kimmeridge clay

loughton. | 5 Upper calcareous Silpho Brow, Sinnington,

60 grit

Wass Bank. 6 Coralline oolite

Scarborough Castle, Pick60

ering, Malton.
7 Lower

Scarborough Castle, Ham

80 Coralline oolite formation. grit

bleton end, Malton, Lea


Scarborough Castle, Salter8 Oxford clay

- 150 gate Brow, Rievaulx

Abbey. 9 Kelloways rock

Scarborough Castle, Hack

ness, Rievaulx Abbey.

} 40 {

40 Scarbor

[blocks in formation]

20 Coal measures 2000 Leeds, Barnsley, Sheffield. Carboniferous formation.21 Mountain lime-) Swaledale, Yoredale, and

20 stone series

Wharfdale. Slate formation. 22 Slate rocks

Ingleton, Sedbergh.

thickness unknown.

Over these strata, is spread the detritus of the deluge, and, in particular places, this is covered by more recent accumulations of peat, clay, &c.


This district is remarkable for presenting, along its whole outline, a range of bold and steep escarpments. Its overhanging cliffs, which so strikingly characterise the coast between Scarborough and Redcar,


are among the loftiest in Britain ; and where it turns inland from Huntcliff, by Rosebury Topping, Burton Head, Dromanby Bank, and Osmotherly moors, it maintains the same high and precipitous aspect, and looks over the plain of Cleveland and Mowbray, as the ranges of Cleeve and Broadway overlook the vales of Gloucestershire. This similarity of appearance is owing to analogy of geological structure. The wide vales of Gloucestershire are, like the vale of Cleveland, based on red marl and lias shale; and the colitic rocks of Cleeve and Broadway are represented, though with great variations, by the rocks of the corresponding escarpments in Yorkshire.

Including that portion of the vale of Cleveland which is based on the lias formation, this division contains about five hundred and fifty square miles. On the south, it is bounded by the elevated edge of oolitic rocks, which range nearly in a straight line, from Scarborough castle to Hambleton end. (See the map.) lt comprehends the whole drainage of the river Esk, and on the north of that river forms an imperfectly connected range of hills, from near Whitby to Rosebury Topping, with detached secondary elevations on the northern coast, at Rockcliff, Huntcliff, and Eston Nab. According to Col. Mudge, the heights on this range are as follow : Rosebury Topping, one thousand and twenty-two feet; Eston Nab, seven hundred and eighty-four feet ; Danby Beacon, nine hundred and sixty-six feet ; Easington Heights, six hundred and eighty-one feet. The Esk flows nearly along the line of a great dislocation, by which the strata on the north of the valley are much depressed. It is on the south of this river that we find the most elevated and extensive moorlands. From the cliff at the High Peak, near Robin Hood's Bay, six hundred feet, a range rises and extends westward by Stow Brow, eight hundred feet, Lilhowe Cross, one thousand feet, Egton moors, and Loose Hoe, fourteen hundred and four feet, to Burton Head, fourteen hundred and eighty-five feet. This is supposed to be the highest point of land in the eastern part of the county, but the ridges are still very lofty which pass by Wainstones, about thirteen hundred feet, and Carlton Bank, round the head of Scugdale, and by Osmotherly moors, to sink beneath the highest point of the next hilly district, at Hambleton end, twelve hundred and fortysix feet above the sea.

The rocks which compose this moorland district rest upon the red marl and sandstone. In the following table, they are numbered according to the general series of Yorkshire strata, pages 32, 33.

Greatest observed thickness.

6 10 Impure, sometimes colitic limestone, full of

shells. (The cornbrash of geologists.)
200 | 11 Sandstone, shale, ironstone, and coal, with car-

bonized wood, ferns, and other fossil plants.

30 12 Impure, often oolitic limestone and ironstone, Carboniferous and colitic

with many fossil shells. (Oolite of Bath.) formation.

13 Sandstone, shale, and coal, with carbonized fossil

plants. 60 14 Subcalcareous, irony sandstone, often containing

shells, called dogger. (Inferior oolite of Somersetshire.)

200 (15 Upper lias shale, or alum shale, with nodules of

argillaceous limestone, ammonites, belemnites,

&c. (Blue marl of Northamptonshire.) 150 | 16 Ironstone and sandstone strata, with terebratulæ,

pectines, cardia, aviculæ, &c. (Marlstone of

Northamptonshire, &c.) 500 17 Lower lias shale, with gryphææ, pinnæ, plagios

tomæ, &c. (Lias shale of Somersetshire.)

Lias formation.

THE LIAS FORMATION.—The lias formation first appears on the seacoast, under the High Peak, near Robin Hood's Bay, and continues along the shore, with only one exception west of Whitby, to Saltburn and Redcar ; being very generally covered, in all the higher cliffs, by the lower portions of the carboniferous formation. Its great thickness is apparent in the sides of Robin Hood's Bay, and in the precipices of Rockcliff. Inland, it follows the sinuosities of the moorlands above Guisborough, by Rosebury Topping, Burton Head, and Carlton Bank, towards Hambleton, and extends a considerable space into the low plains lying to the west of those hills. It is exposed by denudation along a great part of the valley of the Esk, and in many of its tributary branches,

« AnteriorContinuar »