Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/571

 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 Mission of Indiana, where these hills rise nearly 50 feet and are composed of sand and clay; decomposed granite, or gneiss-quartz, occurs as aggregated pieces of conglomerate 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 without any argillaceous admixture.

Above the Mission there are rapids, near which the granite is exposed, and numerous small islands formed by deposits accumulated 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 remains 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 disintegration. The surface of the granite is worn away below the quartz veins that run through it ; and although they present no regularity as by deposition, yet there is such an amount of parallelism as we frequently find in false bedding 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,