66 



^ote oil c§atiott$ of c^toneljcnge ^ocfe^ 

 Irdottjiitg to Ipr. M. Cuimiugton/ 



By J. J. H. Tkall, M.A., F.R.S., Sec. G.S. 



^^[^S these rocks have been described by such able petrologists 



M^'l^ as Professor Nevil Story-Maskelyne and the late Mr. 

 Miv:^ •' ■' 1 ., 1 



Thomas Davies {Wills Mag., vol. xvii., p. 147), any detailed 



description of them is quite uncalled for. I will, therefore, deal 



only with facts bearing on the possible source from which they were 



obtained. The slides submitted to me for examination have been 



taken from rocks which may be classified as follows : — 



Dialases, 40, 71, 21, 63, 56, 55, 35, 48, 36, U. 



Felsites, 52, 51, 65, 67, 50, 66. 



Calcareous Chloritic Schists, 58, 6, 70, 70, 53, 59, 74. 



Grits and Sandstones, 1, 1, 69, 45, 61. 



TJn-named Rocks, all of one type, 73, 68, 57, 60, 19, 33. 



In the above classification I have adopted the names already in use. 



Diabases. 

 These rocks have been described by Professor Nevil Story- 

 Maskelyne, and to his description it is only necessary to add the 

 statement that they are typical ophitie diabases such as occur in 

 many parts of the West of England associated with the Palaeozoic 

 sediments. In British Petrography, p. 232, I have recorded the 

 occurrence o£ rocks of this type at Yealmpton Rock, Park House 

 near Partington, Pollaphaut, Cutacleuse near Padstow, south of 

 Anstie's Cove near Torquay, and at South Petherwin. The col- 

 lections of the Geological Survey contain specimens of the same 

 rock from many other localities, e.g., south of Dittisham Corn Mill, 



^ Numerous specimens of the stones of Stonehenge have been obtained by me 

 during the past half -century ; mostly, with rare exceptions, as noted, from or 

 under the turf within the area of the building. Sections have been cut from 

 man}' of them for microscopic observation, and these having been lately submitted 

 to Mr. Teall for examination, he has favoured the Society with the following 

 important communication. — William Cunnington, London, April, 1893. 



