156 The Geoloijy of tlie Gold Fid(h of Thlti^lt Gnidna. 



granite, and possiljly supplied the carvers of the figures with the 

 material for their implements. 



The granite extends without interruption for nearly one and 

 a half miles south of Waraputa, and is then travei-sed by two 

 dykes of fine-grained diabase al)out a (juarter of a mile apart, both 

 trending north-east and south-west. To somewhat south of the 

 remarkable granitic rock known as Paiwori-Cayra the river runs 

 through masses of coarse-grained granite, which, in places, has a soii'e- 

 what gneissose structure. When the river is low the interruptions 

 caused by these masses of granite in the channels between the islands, 

 with which the river is here dotted, give rise to numerous small rapids. 

 Paivvoi'i-Cayra consists of an immense mass of coarse granitite resting 

 upon a smaller one of the same rock, and forms a striking figure in the 

 scenery of the river. 



Somewhat over a mile south of Paiwori-Cayra the series of rapids 

 and cataracts known as the Haiowa Falls commences, and continues at 

 short intervals for nearly six miles. About a quarter of a mile north 

 of the lowest rapids of this series an exposure of hornblende-schist 

 occurs on the west bank of the channel. The lowest rapid is caused 

 by a dyke of diabase traversing the river from north-west to south-east. 

 Nearly a mile south of this, near the magazine of Greathead and 

 Bascom's Placers in the channel leading to the main falls, is an exposure 

 of pyroxene-gneiss, with a vein of quartz containing porphyritic crystals 

 of hornblende traversing it. For about five miles from this j^lace the 

 channel of the river is much interrupted by many masses of gneiss, 

 pi"oducing frequent rapids and several low cataracts. The gneiss is, in 

 places, traversed by tongues of granitite, aplite and micro-granite. For 

 about a mile and a half above the top rapids of the Haiowa series 

 the river flows quietly between numerous small islands, and its course 

 is uninterrupted until it is traversed by the great dyke of coarse-grained 

 diabase which, trending north-east and south-west, gives rise to the 

 Twasinki Falls. 



South of Twasinki gneiss is the prevalent rock for between six 

 and seven miles. The gneiss varies from a coarse to a fine-grained 

 texture, and at about half a mile south of Twasinki is traversed by 

 a dyke of diabase parallel in direction to the great one at the falls. 

 At the Lower Yucuribi Rapids the gneiss is interrupted by a mass of 

 fine-grained granitite. Half a mile south of the granitite intrusion 

 Great Yucuribi Fall is caused by a dyke of diabase cutting through the 

 gneiss. Near the contact of the gneiss and the basic rock the former has 

 apparently granitic structure, this alteration being similar to those noticed 

 under like conditions elsewhere in the colony. A mile south of Great 

 Yucuribi, Batewa IJapids are caused by a broad el van of granophyre. 

 Half a mile from Batewa Rapids a belt of rocks, consisting of coarse- 

 textured amphil)olite, is exposed at intervals in the river, while south of 

 this Akaiw.mna and Great Itanime Rapids are caused by a broad 

 mass of diabase of medium texture, which on the west side of the river 

 is succeeded by very coarse-textured dial)ase for a distance of over a 

 mile. The weathering of the diabase above Great Itanime is in marked 

 contrast with that of the diabase at and below the cataracts, the former 



