Tlic fJssfqidho RivPT. 157 



strongly i-esembliug that of granite and gneiss, the latter being of the 

 usual angular type. The belt of diabase crosses the river in a north- 

 easterly direction from the Takwari Mountains on the west to the 

 Akaiwanna range of hills on the east. On the east side of the river 

 above the Akaiwanna Cataract coarse-grained sandstones occur dipjiing 

 in a southerly direction. 



Coarse-grained diabase is seen at intervals on the western side of 

 the river to Itababo Island and rapids, the rocks comprising which are 

 of very hard white sandstone or quartzite, and have evidently been 

 greatly altered and indurated by the intrusion of the neighbouring 

 masses of diabase. Somewhat to the north of Takwari Mountain 

 a belt of granophyre, resembling that seen at Batewa Rapids, is 

 exposed . 



The long island in the river south-east of Takwari Mountain is 

 composed of fine-grained sandstone of a red to chocolate colour, thinly 

 bedded, and dipping at an angle of about 20° to the south-south-west. 

 On the western shore of the island is the section represented by 

 C. B. Brown in his sketch No. 4 on page 67 of the " Geological 

 Keports." The sandstone, where nearest to the mountain, but still at a 

 distance of at least a quarter of a mile from its base, changes from 

 a chocolate to a dark-grey colour, and in one place the beds for 

 a distance of some ten to twelve yards are altered to a very compact, 

 black rock of somewhat coarse jasperose texture with a superinduced 

 rectangular jointing, and having a striking I'esemblance to an intrusive 

 igneous rock. Microscopical examination shows the rock to consist of 

 fine-grained feldspathic grits highly metamorphosed by the neighbouring- 

 diabase mass. The red-coloured sandstone on the south of Itababo 

 Island is traversed by a narrow dyke of diabase, an oil-set from the 

 mountain mass, and for a short distance from the edges of the dyke it 

 is changed from a somewhat soft rock to a very hard quartzite of a 

 glistening white ajjipearaiice. As already mentioned, the sandstone on 

 the east of the river extends further north than on the west, and 

 is seen a little south of Akaiwanna Fall. 



