of Devonshire and Cornwall. 103 



ascent and descent as far as the neighbourhood of Ivy -bridge. The 

 red argillaceous sandstone continues from Exeter for some miles on 

 that road ; it is succeeded near Chudleigh by a vast number of flint 

 pebbles, which appear to be scattered over the surface of the ground : 

 I w^as not able to stop to examine them more attentively : but between 

 Chudleigh and Ashburton, there occurs a blue compact limestone, 

 traversed by numerous veins of calcareous spar. At every step the 

 extremities of the strata of this rock may be seen cropping out, and 

 fragments of it are mixed with the soil. In the neigbourhood of 

 Ivy-bridge a formation commences, which as will afterwards be 

 shewn, occupies a prodigious extent in this part of England : I mean 

 the slaty and compact grauwacke. At Plymouth, however, the cliffs 

 on the shore are of limestone ; which as I examined them leisurely, 

 and as they appear to me to excite some degree of interest, I shall 

 describe more minutely. 



The range of tolerably high cliffs, which extends from Stone- 

 house Pool, between Plymouth and Plymouth Dock, and thence 

 along Catwater, ascending the right bank of the Plym as far as the 

 Flying bridge, together with Mount Batten, and probably also the 

 Island of St. Nicholas, are formed of a compact limestone. It oc- 

 curs in strata rising N.N.W. at an angle of about Q5° ; it breaks with 

 a semi-conchoidal fracture into large flakes, is of a yeflowish-white 

 colour, and, when quarried, is blasted with gunpowder. I did not 

 discover in it any impressions of organic bodies, and I did not hear 

 that they have ever been found in it ; at least, if any do exist, they 

 are very scarce. It contains several cavities lined with calcareous 

 spar, or with stalactites, and filled with an ochreous earth. It is 

 frequently also traversed by veins of calcareous spar of a wedge shape, 

 wider at the bottom than at the top, and which generally occupy the 

 whole height of the cliffs. On the side of Catwater, this limestone 



