680 



GEOLOGY. 



The evidence of the landslip appears on the spot, which still retains the name of " The 

 Wonder." A similar event, more ancient, and unrecorded, is clearly traceable in the neigh- 

 bourhood of Ludlow, at the Palmer's Cairns, where strata of Aymestry limestone have slid 

 down from the crest of a hill, exposing the unctuous and argillaceous Lower Ludlow rock. 



But these modern catastrophes are insignificant to the disruptions which, in epochs 

 of unknown remoteness, the Silurian strata have undergone, from the great plutonic masses 

 which protrude through and intermingle with them. The principal igneous rocks asso- 

 ciated with these strata appear in the Caer Caradoc, the culminating point of which rises 

 to the height of 1200 feet above the level of the sea; in the Wrekin, 1330 feet 

 above the sea, and its associate hills, which the traveller discerns in the heart of 

 Staffordshire looming above the southern horizon ; in the Breiddin group ; and in the 

 Malvern Hills, all of which have hard, compact felspar for the predominating material, 

 producing, in different combinations, varieties of pink and dark-red syenite. The intrusion 

 of these fiery products has variously dislocated and inclined the strata lying along their 

 flanks, forced them up, and in some instances even folded them back, so as to make the 

 newer deposits underlie the older ; marked alterations in the character of the stratified 

 formations appearing at the points of contact limestone crystallised, shale indurated, and 

 sandstone rendered quartzose, with the production of copper ore, iron pyrites, and bad 

 serpentine. According to Mr. Murchison, the district furnishes evidence of the play of 

 volcanic action during the deposition of the Lower Silurian strata at the bottom of the sea; 

 of its repose while the upper members of the series were consolidating ; of vast outbursts 

 of intrusive trap subsequently taking place ; and of some of the most violent disturbances 

 transpiring after the accumulation of the old red sandstone and carboniferous systems. 

 Hence the perforations of both with Silurian rocks at Malvern and at Dudley. 



