Rev. S. S. Dor nan — Geology of Basutoland. 113 



been able to discover whether they came from Molteno Eed Beds or 

 Cave Sandstone, but I imagine most likely from the first. Tritylodon 

 has a small and decidedly mammalian -like skull, and is said to have 

 been found at ThabaTsuen, a mountain 16 miles south-west of Morija. 

 It was brought to England \>j Dr. Exton, Curator of the Bloemfontein 

 Museum, and described by Sir Eichard Owen at a meeting of the 

 Geological Society in 1884.^ Dr. Broom, who has recently discussed the 

 affinities of the skull, inclines to the view that it is a mammal. 



(1) The volcanic beds are by far the most typical rock features of 

 the country. They are confined to the high ranges of the Malutis, 

 which form the backbone of the country. The Malutis consist of at 

 least two and in most places three or four parallel ranges of mountains. 

 The average height is 7,500 feet. The necks seem to lie in three or 

 four lines, roughly corresponding to the ranges which now form the 

 Malutis and Drakensberg. A study of the present river system of the 

 country bears out this view, as the Orange River and the Caledon run 

 in approximately parallel courses, and this specially applies to the 

 tributaries on the right or northern bank of the Orange River. The 

 first range of necks builds up the great mountains known as 

 Bitsolebe, Machache, Thaba Phutsoa, and Matelile. The next range, 

 25 miles to the south-west, contains the great necks known as 

 Dikolobeng, Mokhele, and Thaba di Noha. To the north and east of 

 this there is another composed of still higher summits, amongst them 

 not only the highest in Basutoland but in the whole of South Africa, 

 namely. Mount Hamilton 11,500 feet, Leteba's Nek 10,842 feet, 

 Motar 10,400 feet, and Bukotabelo 10,000 feet. The last range 

 composes the mighty wall known as the Drakensberg, and includes the 

 Mont aux Sources 11,170 feet, Champagne Castle 10,357 feet. Giant's 

 Castle 9.657 feet, and many others. Besides these well-defined ranges, 

 there are many other smaller ones scattered around and between them. 

 It must be remembered that many of these heights are not absolutely 

 reliable, as no proper surveys have been made. 



The volcanic beds consist of vast piles of lavas and ashes. Siliceous 

 tuffs are not plentiful. I have seen two or three small examples. 

 The thickness ranges from 500 to 4,000 feet. The lavas are amygdaloid 

 and doleritic near the base of the group, often columnar near their 

 junction with the Cave Sandstone. Higher up in the group truly 

 vesicular and scoriaceous varieties occur, interbedded with thick 

 deposits of ash purple in colour. The greater part of the lavas is 

 amygdaloid, with the cavities filled with quartz or calcite. Weathered 

 surfaces on the lavas indicated by bands of red clay are entirely 

 absent. The thickness of the individual beds varies very much, from 

 a few inches up to 20 feet or more. Many of the flows are full of 

 pipe-like vesicles, usually from 4 to 6 inches in length and from 

 i to f of an inch in diameter, filled with calcite. These vesicles are 

 not quite perpendicular to the plane of the bed, but inclined towards 

 the vent from which the flow took place. They are more or less 

 spherical and often branch at the top. Occasionally the calcite is 

 completely weathered out, leaving the pipes open, so that a bed of lava 

 at its surface and along its fractured edges looks not unlike a honey- 

 1 See Quart. Journ. Geol. Soc, vol. xl (1884), pp. 146-151, pi. vi. 



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