. The geology of the goldfields of British Guiana. from the landing. The creek affordsa succession of excellent sections of the sandstone, which is, as a rule,red in colour and not much indurated. In the course of the creek, upits gorge at a level of about six hundred feet above the river, there is aninteresting section clearly showing the relationship of the sandstone anddiabase. Here a sill of coarse diabase, about eighty feet in thickness,cuts through the sandstone. Below the sill the sandstone has lost its redcolour and is bleached; in places it has been contorted by the intrusiverock, and
. The geology of the goldfields of British Guiana. from the landing. The creek affordsa succession of excellent sections of the sandstone, which is, as a rule,red in colour and not much indurated. In the course of the creek, upits gorge at a level of about six hundred feet above the river, there is aninteresting section clearly showing the relationship of the sandstone anddiabase. Here a sill of coarse diabase, about eighty feet in thickness,cuts through the sandstone. Below the sill the sandstone has lost its redcolour and is bleached; in places it has been contorted by the intrusiverock, and for a depth of two or three feet it has assumed the physicalcharacteristics of quartzite. At the contact the diabase of the sill is verycompact and fine-grained, but this chilled edge is thin, and soon passesinto the coarse-textured rock of which the mass of the diabase is upper part of the sill shows another chilled edge, and the sandstoneabove it is for some distance bleached and altered to a very hard [To face page 162. Tlate SANDSTONE CLIFF, RISINCf OVER 1,000 FEET ABOVE T}IE KIVER AT TUKEIT HEAD OF THE KAIETEUR GORGE, POTARO RIVER. Thoio b,j H. I. Perking [To fave page 162. Plate 23.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectgeology, booksubjectp
