V; ^tlie London and Hampshire Basing. ^^^ 193 



6f^l;efe(*it^. 'Fissures and faults abound in limestblles'kttd'dttflrf^ 

 stones, flexures in clays. Both Dr. Mantell and Mr. Hopkins 

 have observed perpendicular faults of great magnitude in the 

 Hastings sands. There are many minor ones in my own neigh- 

 bourhood, — in the lower greensand ; and there are some remark- 

 able downcasts along the Surrey Hills. T will here describe one 

 of them. Where the traces of the Peasemarsh anticlinal are lost 

 near Albury, a line of disturbance takes off in a north-easterly 

 direction, through the chalk between Shere and Horseley. The 

 farms in the Ordnance Map of Pobley, Green-dean and Pots- 

 dean, between these two villages, mark its direction, till it runs 

 into the transverse fissure of the Mole near Mickleham. Here- 

 about are the " swallow-holes " of the Mole, in which that river 

 is lost in the summer season; and they are probably caused by 

 the joint operation of these two lines of disturbance. Taking the 

 direct footpath from Horseley to Shere, after crossing the chalk 

 downs of the former place, you find yourself on a distinct though 

 low escarpment of chalk descending on Netley Heath, which 

 consists of sand of the plastic clay formation. Crossing Netley 

 Heath, you come again on the chalk, and the descent of the 

 deep escai-pment to Shere, makes you sensible of having traversed 

 the whole thickness of the latter formation. East of the Vale of 

 Mickleham there are patches of tertiary, as at Headley, with 

 signs of much disturbance thereabout, as at Pebble Hill, — one 

 of those deep fissures filled with loam and shingle so often met 

 with in the chalk. jiwiiuj 



To return to the structure of the Weald. Mr. Hopkinsr hiSi^ 

 distinguished flexures from anticlinals : why should they differ, 

 except as in degree or shape ? The flexure, which by its sudden 

 dip north gives rise to the Hogsback, is an anticlinal, twisted to 

 one side, that is, of unequal dip*. As it recedes from the chalk, 

 it becomes a perfect anticlinal at Peasemarsh ; and the Vale of 

 Peasemarsh is a true ^^ Valley of Elevation -/' as distinctly so as 

 that of Kingsclere, first described by Dr. Buckland. Again, 

 Mr. Hopkins has noted a flexure at Pulborough north of the 

 line of the Greenhurst anticlinal. This flexure is no more than 

 the commencement or northern edge of the sjmclinal of the last- 

 mentioned line, and the trough of gait at Hardham ; the river 

 Arun taking its course along the same depression. These 

 flexures, when not seeming to have any relation to distinct anti- 

 clinals, very much modify the surface arrangements; and are 

 instrumental also in the production of springs and water-coursfes j 

 and, moreover, like faults and anticlinals, they prolong the out- 

 crop of the strata in which they are found. There is a remark- 

 able one of this sort crossed by the lane leading from West 

 * Phil. Mag. p. 48. ^' * " 



