the Parallelism of Contemporaneous Lines of Elevation. 409 



line, also ranges N. and S., and presents shattered masses of 

 transition lime and trap on its sides. Trap rocks occur here 

 also; the surrounding new red sandstone is horizontal and 

 undisturbed. The Warwickshire coal-field, between Coventry 

 and Tamworth, together with a subjacent narrow tract of 

 quartz and grauwacke on its north-eastern border, is elevated 

 in a line of direction N.N.W. and S.S.E. Greenstone dykes 

 intersect the subjacent grauwacke at Griff' near Bedworth. 



The elevation of the sienitic and schistose ranges of Charn- 

 wood Forest may next be noticed ; for as the contiguous 

 coal-measures at Grace Dien, and the magnesian beds of the 

 carboniferous limestone at Breedon, appear to have been af- 

 fected by the same convulsion, while the surrounding new red 

 sandstone is undisturbed, this elevation must be referred to 

 the aera we are now considering. In this view it may be com- 

 pared to the eruption of the Malvern sienite and the various 

 trap rocks of the Wrekin chain, which we have already re- 

 ferred to the same age*. 



We new proceed to the great central ridge of the northern 

 counties : this, as is well known,' presents a central line of car- 

 boniferous limestone, ranging N. and S., having lateral zones 

 of coal-measures on the east and west, which are overlaid on 

 the east by the regular zone of magnesian limestone, as also 

 on the west, if we consider tins system as extending round the 

 northern edge of the transition chains of Cumberland to 

 Whitehaven. The magnesian limestone is separated from the 

 coal-measures by a bed of sandstone representing the rothetodte 

 of Northern Germany. Now as the magnesian limestone and 

 its subjacent rothe todte repose unconformnbly on the elevated 

 coal-measures, it is obvious that this elevation in a great mea- 

 sure took place anteriorly to the deposition of these super- 

 strata. But again, as the rothe todte is often inclined when the 

 superincumbent magnesian conglomerate and limestone is ho- 

 rizontal, we must suppose a second aera of convulsion posterior 



* The first appearance of these rocks at Mount Sorrel exhibits a low 

 ridge of well characterized sienite bursting through the red marl. A flat 

 tract, concealed by this red marl, separates the Mount Sorrel ridge from 

 the Swithland slate district on the west. This slate has rather the charac- 

 ters of greenstone slate than grauwacke : it alternates with and passes into 

 greenstone and greenstone porphyry. The sienite presents several insulated 

 portions emerging through the red marl south of Leicester along the 

 western bank of the Soar, viz. Endcrby Croft hill, beneath which the Soar 

 flows through a defile of sienitic rocks, forming a sort of spur proceeding 

 from the hill; Stony Stanton, where undisturbed beds of the red marl 

 may be seen close to the sienite north of the village; and Shopcot, about 

 a mile further south. The best account of Charn wood Forest will be found 

 in the Annals of Philosophy for .January 1824. — [See also a notice of Prof. 

 Sedgwick's late examination of Charnwood Forest, in our .Number lor 

 January last ; present vol. p. 68. — Edit.] 



Third Sain. Vol. 1. No. 24. June 1834-. 3 G 



