108 



owing to the action of carbonic acid, held in water, gradually 

 percolating, eroding, and forming openings or fissures.* 



Clayey Partings. Clayey Partings. 



When Mr. Playne mentioned the finding of the Quartz 

 Pebbles to the late Mr. John Morton, author of " Morton on 



* I have since visited the Quarry witli the Cotteswold Club, and subsequently 

 with Mr. Etheeidge, and on both occasions found several Quartz Pebbles, and 

 not confined to one opening in the clayey partings. These fissures or 

 openings seem to be general in Oolitic quan-ies, and it is singular that near 

 Cirencester the openings or joints, like those at Woodchester, strike north and 

 south. I am indebted to Professor Church, of the Cirencester College, for the 

 following analyses of the clay taken out of the quarries refen-ed to : — 



I_ — Clay from fissm-es in Oolite, Stroud Eoad, near Eoyal Agricultural 

 College, Dark Purplish Brown. Sectile, Saponaceous. 



Organic Matter and Water of Combination 11-43 per cent. 



Silica 53-95 



Alumina and Oxide of Iron 31-88 „ 



Carbonate of Lime 1-95 „ 



Carbonate of Magnesia "75 „ 



99-96 



With traces of Chlorine, Sulphuric Acid, and Alkalies, and some Manganese. 



