iS 
great extent of the volcanic rocks visible; they were seen about 5 
or 6 miles west of the mountain, to rest upon quartzites, which oc- 
cupied the country as far as the tidal waters of the drowned 
vadey of the Prince Regent River. 
Jn the vicinity of Synnot Creek in the King Leopold Plateau, 
is a very coarse volcanic breccia which covers a very wide area, 
and is associated with the lava flows; as a rule the ashy beds are 
Fig. I8. 
Volcanic Breccia, Synnot Creek, King Leopold Plateau, 
Kimberley Division. 
very much finer in grain than that shown in Fig, 18. In 
this particular instance, it seems quite clear that the coarse 
agglomerate occu])ies the throat of one of the volcanic vents which 
has not yet entirely disai)peared Iw denudation; it is still surround- 
ed by lava Hows and fine-grained ashy beds. In the heart of the 
Hamersloy Range (or i)lateHu) the sedimentary rocks may be 
seen underlying the Ijeds of the volcanic series. (Pig. 10). 
In certain localities these volcanic rocks reach a very consider- 
able thickness, often over 500 feet. 
So far as onr ol)servations have been carried, it appears that, 
as a rule these lavas have tlie composition of basalts or dolerites. 
