CHAPTER XXI. 



THE BERBICE RIVER. 



(C. W. Andersox.) 



The Berbice River from the Atlantic Ocean has a sinuous course of 

 about one hundred and sixty miles in a general south-south-westerly 

 direction to Yowanna Island, and passes through alluvial deposits 

 consisting of coast alluvium, arenaceous clays and sand beds, an 

 accurate and detailed account of which is given by C. B. Brown in 

 Report No. 11 published in the "Reports on the Geology of British 

 Guiana " by Sawkins and Brown, dated 1875. On the left bank of the 

 river, opposite Yowanna Island, cliffs occur about ninety feet high, 

 composed of red ami white coloured clays and sand. About two miles 

 above, just below Waramuri Itabu, the first exposure of rocks is seen, 

 situated low down on the left bank of the river ; they consist of an 

 extremely hard felsite. 



In the Waramuri Itabu a blackish coloured sandstone is exposed on 

 the right bank. Near Kabouriwa inlet the river banks are formed of 

 whitish clay, and about half a mile above Kabouriwa Creek some rocks 

 in the river consist of a dark brownish coloured and thinly stratified 

 sandstone. 



For a distance of about four hundred and fifty yards above Kawashi 

 Inlet a belt of epidiorite extends across the river. 



Thence no rocks are exposed in the river for a distance of about 

 eight miles up to Sirikuru Shallows, where the river flows over a belt 

 of ferruginous conglomerate. Along- this stretch of river the banks, 

 during the dry season, are from fifteen to eighteen feet high, and are 

 composed of broken masses of an admixture of sand and clay having a 

 rock-like appearance. 



About two miles above Sirikuru the river is joined by the Kuruduni 

 Creek, a large tributary on the right bank. On some hills situate about 

 two miles up this tributary beds of quartz-conglomerate occur, 

 containing large pebbles in a siliceous cement similar to that found at 

 the Kaieteur Falls on the Potaro River. Between the Kuruduni 

 Creek and Muka-Muka Inlet, near the landing of a path to the 

 Demerara River, are sonae rock-exposures which consist of gabbro ; 

 these are mentioned as being the first rocks observed by C. B. Brown 

 on the river, and are described by him as "greenstone." 



Below Hubudi-Kabura the gabbro has been decomposed, giving rise 

 to high banks of ironstone containing innumerable vesicles, while 

 between the Kairuni Creek and an inlet of the same name the 

 unaltered rock again appears. 



