172 



PROF. T. T. GROOM ON THE IGNEOUS ROCKS [Feb. IQOI, 



Table II. 

 Olivine-Basalts which have been Microscopically examined.^ 



JSTo. 



Locality. 



Probable i 

 I Mode of 1 

 \Occurrence\ 



Colour, 



Specific 

 Gravity. 



Per- 

 centage 

 of Silica. 



236 

 117ft 



102 



108 



117a 



118 



119 



197 



214 



216 



218 



247 



248 



249 



263/ 

 263 i 

 263 it 



268 



HoLLYBusH Sandstone. 



Eaggetbtoue Hill, west. ; Boss. 



Northern end of Chase : Sill. 

 End Hill. 



I Dark greenish- 

 j Brownish-green 



West of Pendock's 



Grove. 

 Near Brousil. , Laccolite. 



Chase End Hill, north. ; Sill. 



South of White-Leaved \ Sill. 



Oak. I 



Roadside south-west of Laccolite. 



White- Leaved Oak. 

 West of Pendock's Sill. 



Grove. 

 North-west of White- Sill. 



Leaved Oak. 

 Little south-west of 214.^ Sill. 



Western spur of ('hase Sill. 



End Hill. I 



North-east of Bronsil 



Upper Cambrian Shales. 

 Laccolite. Dark green. 



North of Bronsil. 

 North of Bronsil. 



I Immediately north- 

 j east of Coal Hill. 



Small quarry,!)}^ cottage, 

 south-west of White- 

 Leaved Oak. 



Laccolite. 

 Laccolite. 

 Laccolite. 



Jjacco- 

 lito. 



Laccolite. 



Dark bluish- 

 grey. 



Light bluish - 

 grey. 



Dark greyish- 

 gi'een. 



Dirtj' greenish 

 grey. 



Dark grej'ish- 

 green. 



Dark greyish - 

 blue. 



Greenish-blue. 



Bluish-grej'. 

 Greyish-blue. 

 Greenish-grey. 

 Greyish -blue. 



\ Gi'ej'ish-blue, 

 Greyish-blue. 



2-70 

 2-56 



Pheno- 

 crysts. 



2-66 





2-73 



39-252 



2-75 





2-82 





2-71 



42-42 



2-62 





2-76 



40-00 



C2-67 

 t2-61 





r ® 



YI. Ophitic Olivine-Diabases. (PI. VII, fig. 1.) 



With two doubtful exceptions (M 372 & 447) the diabases 

 appear to be confined to the Coal-Hill band ^ of the Grey Shales. 

 They occur as sills, and probably as small laccolites and bosses. 

 The relation of the sills to the Grey Shales is admirably seen at 

 €oal Hill Cottage (fig. 10, p. 173). 



^ Altogether twenty slices. 



'" This analysis may refer to No. 248. 



•^ Quart. Journ. aeol. Soc. vol. Iv (1899) p. 169. 



