103 



the edges of what might be likened to the leaves of an enormous volume, of 

 Bome 8 or 10 miles in thicltness. The Longmyuds alone measure, according to 

 Ramsay, 26,000 feet, which estimate, however, Mr. Salter thinks may be reduced 

 by the doubling over of some strata, whereby they would be counted twice 

 ever. However, even if we take the smallest estimate of 10,000 feet, no one 

 can examine the structure of these rocks, which shows that they were for the 

 most part deposited on a succession of level sea beaches, exhibiting thin cracks, 

 ripple marks, and the traces of worms which crawled over their surface when 

 they were laid bare by the receeding tide, without being impressed by the 

 immensity of time required to form them. Such evidences meeting 

 the geologist wherever he turns — evidences as certain at least as any upon 

 which he can rely upon all ordinary subjects of knowledge — convince him that 

 cycles of time may be assigned to the production of these strata as liberally as 

 space is assigned to contain the countless worlds which we witness on a stany 

 night. 



Tliis part of the country is not devoid of evidences of the violent 

 action which even in the present day produces sudden changes in the crust of 

 the earth. In the Corndon and in several masses of igneous rock in the neigh- 

 bourhood are to be found traces of the forces which have elevated the Long- 

 mynds and the surrounding country ; besides the course grit and felspathic ash 

 which are often found there interstratified with clay shale, are memorials of 

 great submarine volcanoes which time after time cast up cones of lava and 

 ashes from the bed of the sea, these were then dispersed in every direction till 

 the cone was levelled and disappeared beneath the waves, and the whole was 

 then overlayed with a stratum of clay. Upon the nearer side of the Longmynd 

 the strata is sufficiently regular, but it is not so easy to determine their exact 

 relation to the rocks on the other side. This is caused bj' a vast fault of some 

 2,000 feet along the Stretton Valley which has cut off the upper strata from 

 the lower as seen on the western side of the ridge. There seems reason to 

 believe that the Caradoc is only the upper member of a long and regular series 

 of which the lowest is the Arenig— but however that may be the Caradoc strata 

 on this side of the range are deposited on the edges of the Cambrian rocks, whUe 

 on the other, the Stiperstone flags and Llandeilo are conformable to them. 



Before leaving the neighbourhood of these hills we must notice a fact which 

 throws light on their early condition and history. We find along most of their 

 eastern flank, and also along their southern extremity and a portion of their 

 western flank, a stratum of the IMayhiU grit and conglomerate succeeded by the 

 lower beds of purple Wenlock shale ; a little consideration of this fact will suggest 

 an important inference ; we find these strata dipping at a tolerably equal angle on 

 every side away from the strata on which they lie — such an arrangement seems 

 only explicable on the supposition of their having formed a portion of an ancient 

 beach along the Longmynds as a shore — observe that a similar deposit is made 

 all along the coast of any existing land : all along the western shores of our island, 



