1871.J 



SAWJKINS — URTTISH GUIANA. 



421 



On reaching the western shore 

 of the Essequebo, my course was 

 nearly south-west to Supinaam 

 Creek, which courses along the 

 base of the sand- hills to the Mis- 

 sion of Indiana, where these hills 

 rise nearly 50 feet and are com- 

 posed of sand and clay; decom- 

 posed granite, or gneiss-quartz, 

 occurs as aggregated pieces of con- 

 glomerate cemented by red or 

 white clay. Where the clays are 

 separated from sands, they are 

 mottled or streaked with red lines 

 of oxide of iron. Sand-deposits 

 increase in ascending the creek, 

 and occur in many instances with- 

 out any argillaceous admixture. 



Above the Mission there are ra- 

 pids, near which the granite is 

 exposed, and numerous small is- 

 lands formed by deposits accumu- 

 lated on it. 



In proceeding up the Groote 

 Creek, which runs parallel to the 

 Supinaam on the south, the same 

 series of granite rocks is exposed 

 here and there, and likewise along 

 the banks, under deposits of sand 

 and clay. 



Saxacalli point is composed of 

 granite and appears to be the re- 

 mains of a dyke that extended 

 across the Essequebo river. On 

 examination it was found that none 

 of the rocks composing this group 

 presented any sharp edges ; all are 

 rounded by attrition or disinte- 

 gration. The surface of the granite 

 is worn away below the quartz 

 veins that run through it ; and al- 

 though they present no regula- 

 rity as by deposition, yet there is 

 such an amount of parallelism as 

 we frequently find in false bed- 

 ding of sand and gravel, while the 

 lines of separation in the granite 

 are more constant in one direction, 

 dividing the quartz veins as well 

 as the granite. At Swarte Point, 



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