426 REV. G. BLENCOWE ON CERTAIIT GEOLOGICAL FACTS 



32. Oil certain Geological Facts witnessed in I^atal and the 

 Boeder Coun^tries during nineteen Tears'' Residence. By the 

 Eev. George Blei^cowe. Communicated by Eev. Henry 

 Grieeith, E.G.S. (Bead November 19, 1879.) 



The basal strata of ITatal as seen on the coast are shales, which are 

 succeeded by sandstones of various kinds for from twenty to twenty- 

 five miles into the interior, after which, about the same distance of 

 hard shale occurs in deep beds. The valley of the TJmgeni seems to 

 have been formed by subsidence, as the sandstone hills in the neigh- 

 bourhood are greatly cross-fractured, and the beds dip with an 

 inclination nearly corresponding to the surface-curve. This also is 

 the case with other, shallower valleys in the neighbourhood. There 

 are also, on the upper edge of the northern side of the Umgeni valley, 

 cliffs, from which the front has fallen away, which are without a 

 dip, as also in several other cases in the vicinity where the original 

 level has been maintained, the edge of which presents a perpendicu- 

 lar cliff. 



In the northern and north-western portion of J^atal a white 

 sandstone prevails, which increases in the thickness and hardness of 

 the strata as we ascend. This part is a succession of irregular 

 ridges and truncated cones in every variety of relative position. 

 The present configuration seems to have arisen from denudation, as 

 the sandstone of the remaining hills is horizontal and without cross- 

 fracture. There is also a high plateau, known as the Biggars-Berg, 

 about 50 miles long, which corresponds in structure and height with 

 the highest of the remaining hills, and appears to be the only part 

 which has been free from the denuding force which has scooped out 

 the valleys and abraded the hills around. The substance of this 

 plateau is sandstone, in strata from 3 to 20 feet thick ; and it has a 

 capping of trap, which is generally basaltic, and from 20 to 100 feet 

 thick, while the average height above the surrounding valleys is 

 about 1000 feet. The surrounding valleys are thickly strewn with 

 broken-up trap of sharp angularity, which forbids the supposition 

 that the fragments have been brought by a stream from a distance, 

 but implies that they are near where they first fell. 



In this district of horizontal sandstone the coal of this part of 

 South Africa is found ; and the seams reach from a few miles to the 

 north of Ladysmith to the edge of the mountains in the Lydenburg 

 district of the Transvaal, and east and west from near Borke's Drift 

 to a few miles east of the junction of the Mooi river with the Yaal. 

 There has been no search for coal ; and it is only known where it has 

 been casually seen in the face of a cliff or in the bottom of a water- 

 course. On the Dundee and adjoining .farm, there is one seam 10 

 feet thick; and about a quarter of a mile further up, at a perpendicular 



