ENGLAND. 



715 



Iui5tt.ru.-. 



jine district. The strata of the middle district rise at 

 an elevated angle, as they approach the granite rocks 

 of this range. The western bour.dary of the coal dis- 

 trict in Somersetshire is formed of metalliferous lime- 

 stone and grey wacke, which pass from that county 

 into Devonshire and Cornwall. Mountains of granite 

 extend from Dartmoor to the Laud's End. Slate, grey 

 wacke, and sometimes mt caiut'erou- limestone, occur 

 on their declivities anJ summits. At the Li/ard, the 

 granitic rocks are covered with .serpentine., near which 

 diallage in rocks is found. In the serpentine also, soft 

 steatite is imbedded. The most extensive and valuable 

 mineral treasures of this part of the alpine district are 

 copper and tin ; besides thtse, ores of silver, cobalt, 

 bismuth, manganese, antimony, zinc, and iron are 

 found. Indeed, it has been remarked, that all the 27 

 known metals are met with in Cornwall, except plati- 

 n;' ; mercury, molybdeua, tellurium, tantalium, Colum- 

 bian, and cerium. In some of the granite rocks of 

 Cornwall, schorl is found intermixed; and in some par- 

 ticular places, it constitutes the principal part of the 

 rock. 



Having given this general sketch of the mineral geo- 

 graphy and geology of England and Wales, arranged 

 into districts, we shall now proceed, in order more 

 fully to illustrate this important subject, to offer some 

 iianeous remarks, though at the risk of repeating 

 some of the statements which have been already made. 

 To begin with the primary rocks. Granite and gra- 

 nitic rocks occur in Cornwall, Devonshire, North Wales, 

 Anglesea, the Malvern Hills in Worcestershire, Charn- 

 wood Forest in Leicestershire, and in Cumberland and 

 Westmoreland. The granite of these two counties is, 

 however, porphyritic; and that of Charnwood nearly 

 allied to sienite. Blocks of granite are found detached 

 in some parts of Lancashire and Cheshire. Gneis is 

 found nowhere in England, except at the Malvern 

 Hills; and here it is imperfectly formed. Mica slate 

 occurs only in Cornwall, where, along with it, lying 

 over granite, serpentine, another primary rock, is also 

 found exclusively, with the exception of the Isle of 

 AngleMB. 



Of the intermediate or transition rocks, slate is found 

 in Westmoreland, Yorkshire, Leicestershire, North 

 Wales, Cornwall, and Devonshire. In the Yorkshire 

 slate are cubic crystals of pyrites. In the slate rock 

 at Charnwood Forest, in Leicestershire, the slaty la- 

 minae make an angle of 60 degrees with the principal 

 seam, by which the rock is divided. Graywacke is 

 met with in Cornwall, where it is called killas. In the 

 northern part of Radnorshire is a lofty range of moun- 

 tains, composed of graywacke, which, on the eastern 

 ide, resembles sandstone, and on the western, roof- 

 akte. 



The compact limestone of England and Wales be- 

 longs properly to the transition rocks. In Yorkshire 

 and the northern counties it rests on slate, and con- 

 tains a greater quantity of organic remains than the De- 

 vonshire limestone. Trap, or greenstone, is met with 

 in Cornwall in transition rocks ; but it possesses no cha- 

 racters by which it can be distinguished from that 

 found in primary rocks. 



Transitions from granite to sienite and greenstone 

 occur in the same block at Chaniwood Forest. The 

 two latter are also met with in Cornwall, Wales, and 

 Cumberland. Amygdaloid, provincially called toad- 

 stone, is found in great abundance in Derbyshire. 

 Porphyry occurs in the westej-n side of England and 

 Wales. It has already been mentioned, that porphy. 

 3 



ritic greenstone is scattered over the northern side of Statistics. 

 Cader Idris. Basalt is found in Durham, Shropshire, " -v ~ ' 

 &c. 



The lowest of the secondary rocks in England is 

 frequently a silicious sandstone, coloured by red oxide 

 of iron, and called red sandstone: this has been al- 

 ready described. The secondary rocks also include ar- 

 gillaceous sandstone, earthy limestone, calcareous sand- 

 stone, and chalk ; and contain, besides the rock-salt, 

 gypsum, iron-stone, coal, and basalt. On the eastern 

 side of England, the coal strata generally decline to 

 the south-east ; on the western side, they are more fre- 

 quently thrown into different and opposite directions, 

 by faults and dikes. The deepest coal mines in Eng- Deepest 

 land are those of Northumberland and Durham, some ce 

 of which are wrought more than 300 yards below the 

 surface The thickest bed of English coal is in Staf- 

 fordshire, which is 30 feet deep. In general, the beds 

 of coal in other parts of England and Wales do not 

 exceed from 6 to 9 feet in thickness. From the account 

 which we have already given of the low district of 

 England, it will be apparent, that there is more than 

 one third of this country, in which all searcli for valu- 

 able coal is useless. 



With respect to the upper secondary rocks, and the strata con- 

 strata containing organic remains in England, there are tainingor- 

 magnesian limestone, chalk, flint, gypsum, the marie ganicre-^ 

 and sand, over which, in many parts, contain a large mams - 

 quantity of red oxide of iron. Gypsum is principally 

 found in Cheshire, Shropshire, Worcestershire, Derby- 

 shire, and Nottinghamshire. In the gypsum of the 

 two latter counties, no organic remains have been dis- 

 covered. The organic remains found in the clay and 

 gravel which covers the chalk in the southern counties, 

 have already been noticed. The gravel over the clay 

 is composed principally of flint, containing distinct 

 impressions of unknown aquatic animals. Between 

 the clay and the gravel, there is sometimes a thin layer 

 of fresh-water shells, which are also met with under 

 the clay. In the strata over chalk, in the Isle of Wight, 

 fresh-water shells have lately been detected. 



If we were to cross England, from Hull into Lanca- Strata from 

 shire, we should first meet with a flat country, formed J 1 " 11 io , . 

 of alluvial ground. A few miles to the west of this 

 town, the laud becomes more elevated, and we pass 

 over a range of chalk hills, which compose the southern 

 extremity of the Yorkshire Wolds. After descending 

 from these hills, near the Humber, we again enter on 

 alluvial ground, covered with clay and gravel, which 

 extends nearly to Ferrybridge. Here the magnesian 

 limestone makes its appearance, which, with the earthy 

 limestone, form hills of a low elevation, distinctly stra- 

 tified. The strata are nearly horizontal, and divided 

 by seams of clay. The extreme breadth of this range 

 of hills is not more than three miles. Yellow silicious 

 sandstone comes next, which is the boundary of the 

 low calcareous district. Proceeding towards Wakefield, 

 the argillaceous coal strata of the middle district, ex- 

 tending westward more than 20 miles, is met with. 

 Wakefield and Leeds stand near the east side of the 

 coal district, and Huddersfield and Halifax near the 

 western. A few miles to the west of these towns, and 

 also of Sheffield, hills, composed of millstone grit and 

 shale grit, rise from under the coal strata. These are 

 more than 300 yards thick, and no workable coal is 

 ever found in them. The bases of these hills is metal- 

 liferous limestone. If we proceed still farther to the 

 west toward Manchester, we descend the steep west- 

 em, declivities to the plains of Lancashire ; and, lea- 



