6 
done, it is not meant to imply that the rocks so designated in the 
Northern Hemisphere and elsewhere are exactly contemporaneous. 
As may he seen hy a glance at the geological sketch map (Fig. 
6), the great bulk of the interior plateau is granite and gneiss, the 
remainder being formed of the metaniorphic rocks, the whole form- 
ing th foundation upon which the Palaeozoic and more recent 
super-structure has l)een Iniilt. 
Fig. 6. 
