1^8 ON COLOURING GEO GNOSTIC AL MAPS. 



out strata inclined under an angle of 70 ° ; the 

 second arrow, strata under an angle of 50 0 ; the 

 third arrow, strata under an angle of 25 °. Pro- 

 bably an equally convenient mode would be to 

 mark the angle of inclination alongside the arrow, 

 and proportion its size to the length of the map. 

 Thus, if the map were on a large scale, the arrow 

 might be -J of an inch long ; if on a smaller scale, 

 I inch, or even \ of an inch in length. The 

 highest points on a mountain range should be di- 

 stinguished by a cross h^-i ? a level, by a figure 



resembling a door and a shaft, by a 



lengthened square | ( . 



The following tabular view of the dirferent 

 Colours that should be employed in geogriostical 

 maps, will be found useful. 



WHITE COLOURS. 



Quartz. Reddish-white, slightly inclining to. 



yellowish white. 

 Chalk: Milk-white. 



Sand:. Yellowish-white, faintly inclining to 



reddish- white. 



Mica-slate. 

 Primitive- ' 



CI ays late 



GREY COLOURS.. 



Pearl- grey. 



Pale greenish-grey, falling into blu- 

 ish-grey. 



