internal Structure oJtJie Magnesian Limestone. 45 



hilly ground east of Castleford ou the river Air, the terrace gradually declines in elevation but 

 continues sufficiently well defined to admit of its being correctly delineated. Indeed on any map 

 which fairly represented the great features of the country, it would hardly be possible to make 

 any great error in the general range of the boundary line ; the only difficulty would be in cor. 

 rectly delineating the indentations formed by the valleys of denudation*. 



The beds of limestone near the boundary of the formation on the left bank of the Air appear 

 very little above the level of the country on their western side ; but they are l)acked to the north- 

 east by hills of considerable elevation. Near Kippax Park the line of demarcation again begins 

 to rise along the top of a terrace, which, in its range towards the north, is, however, devious in its 

 direction, and in many places ill defined. Kippax, the east end of Parlington Park, Potterton 

 Kidhall, Scarcroft, and Iligton, are close to the edge of the escarpment. From the hill above 

 Collingham the line gradually descends towards the Wharf, and crosses its bed a little above 

 Wetherby. As this part of the geological county map is very inaccurate, I have subjoined a 

 coloured outline map of the district, which will give a better general notion of the range of the 

 magnesian limestone, and also of the position of several outliers, than can be conveyed by verbal 

 description f. 



On the left bank of the Wharf the limestone gradually ascends, in a direction nearly parallel to 

 the river, as far as Linton ; from thence it turns round the top of the liill to Linton-Spring without 

 making any feature on the surface ; then ranges to Stockeld Hall, crosses the Spoftbrth road, and 

 dellects considerably to the south-east to Wetherby Grange. The boundary then ranges in the 

 form of a low terrace to Ribston, passing about half a mile east of North-Deighton. From 

 Ribston the line ranges along the top of the hill above Plumpton, and from thence along the 

 crown of the hills which form the right bank of the Nid immediately to the south of Knares- 

 borough. The greater part of this range from Ribston is difficult to determine correctly ; because 

 the limestone, without making any escarpment, only forms a thin irregular capping on the plateau 

 of sandstone, and is in some places concealed by diluvium ; and also because in the published 

 maps of the county there is no adecpiate representation of the natural features of the country. 



The range from Knaresborough to Ripon is very incorrectly laid down in the map of Yorkshire, 

 and three or four outliers are omitted. The accompanying map J, and the following memoranda, 

 will assist in bringing the delineation much nearer to the truth. 



The limestone, after descending from the crown of the hills above mentioned, ranges through 

 the woods on the south bank of the Nid, crosses the Ilarrowgate road in the brow of the hill im. 

 mediately above the bridge, and extends along the upper part of the same bank (though in a very 

 obscure form, and much disguised with diluvium) a few hundred yards further to the uorth.west. 

 It crosses the bed of the river nearly opposite the Hall, and ascends along the north bank con. 

 siderably higher, capping a part of Scotton Moor as far as the brow of the hill south-east of the 

 village : from thence the line ranges on the edge of the plateau south of Scriven, to the north side 

 of Knaresborough. It then makes a deflection to the cast, and the demarcation afterwards passes, 

 in the form of a low ill.defined terrace, by Gibbet House and Farnham, and descends into a 

 vallej of denudation a little above Okeney. On the other side of the valley the limestone occupies 



* The irregularities of the line of demarcation in this part of the range are in general well re- 

 presented in the geological map of Yorkshire. The line from Dinniugton to Laughton is made 

 to deflect a little too much to the north-east; and the limestone j*/rt/;e«wx of IIooton-Lovett and 

 Maltby ought to approach a little nearer to each other. Some other slight inaccuracies in the 

 representation of the range near the banks of the Don are corrected in the accompanying map. 

 (See Plate IV. fig. 4.) 



t See the accompanying map (Plate IV. No, 2). X See Plate IV. No. 1. 



