VlCINlTr of EDINBURGH. 43 t 



19th March. 



Since I had the honour of reading the foregoing paper to 

 the Society, a ftrong cafe in illuftration of what is mentioned 

 in the commencement of it, has prefented itfelf ; I mean, with 

 refpecl to the conftant occurrence of new and interefting mat- 

 ter, even in the mofl frequented ground. 



A few days ago, ProfefTor Playfair mentioned to me, that 

 by the cutting down of a fection of the Craig, within thirty 

 paces of the fouthern extremity, feveral maffes of fandftone 

 had made their appearance, imbedded in the greenftone. I 

 loft no time in vifiting the fpot, and was greatly pleafed to find, 

 a confiderable addition to the interefting fads, already exhibit- 

 ed on Salifbury Craig. 



At this part of the rock, the greenftone becomes very thin, 

 being no more than twenty to twenty-five feet thick ; it has the 

 appearance, however, of having once been of greater extent, 

 the upper part being apparently cut away by fome operation of 

 nature, of which we have now only to obferve the effects. It 

 Hopes rapidly towards the fouth, and is covered to a confider- 

 able depth with foil and travelled ftones. It is at the upper 

 furface of this, that the imbedded mafTes occur ', they appear 

 to be portions of ftrata, which obferve the general inclination 

 of the fandftone of Salifbury Craig, that is, dipping towards 

 the north-eaft, while the expofed fections are parallel to each 

 other, and nearly horizontal ; confequently, being near the fur- 

 face, they are cut off, or crop out, on the fouth fide. Their 



appearance, 



