ON COLOURING GEOGNOSTICAL MAPS. I$f 



other, so that they may not appear indistinct 

 and give rise to confusion. 



All mountain-rocks, therefore, ought to be 

 coloured according to the preceding rules ; and 

 the particular rocks distinguished by certain co- 

 lours. 



For this purpose, the following colours have 

 been recommended by Werner, and I have prefix- 

 ed to each rock the particular symbol employed 

 by him to distinguish them. 



) I ( Quartz. — Reddish-white, inclining a little to 

 yellow. 



i^l Topaz-rock. — Pale brick-red. 



m 



Granite. — Pale cochineal-red, approaching 

 carmine-red. 



White-stone. — Pale flesh-red, 



Gneiss. — Lilac-blue. 

 Mica-slate.— Pearl-grey. 



Primitive Clay-slate. — -Greenish-grey, fall 

 irig into blue, 



k 4 



