﻿84 PROF. A. c. SEWARD ON [Feb. 1908, 



j Volcanic Beds. 

 Upper Karroo or j Cave Sandstones. 

 Stormberg Series. | Red Beds. 



LMolteno Beds. 



In his account of the ' Geological Survey of the Divisions of 

 Aliwal North, Herschel, Barkley East, and part of ^odehouse,' 

 Mr. Du Toit writes ' :— 



' There is a marked lithologieal difference between the Burghersdorp and the 

 Molteno Beds. Bed and purple are the predominating tints of the softer 

 rocks in the lower formation, and there are never anj carbonaceous beds. 

 Consequently it has been thought necessary to draw the dividing-line at 

 the summit of these bright-coloured rocks and place them in the Beaufort 

 Series. It must be admitted that to our present knowledge this boundary-line 

 is not coincident with one and the same stratigraphical horizon throughout, as 

 the colouring occasionally rises very close to that important geological bench- 

 mark the 'Indwe Sandstone,' while at other places it is very much below it. , . . 

 The age of the Burghei'sdorp Beds is proved by the fossils they contain. The 

 presence of the labyrinthodonts and fishes indicates that the formation is 

 homotaxial with the Keuper (Upper Trias) of Europe. The Burghersdorp 

 Beds may also be considered to be equivalent to the Hawkesbury Series of 

 I^ew South Wales, which also contains labyrinthodont-remains and fishes of 

 not only the same genera, but of closely allied species. The age of the Aus- 

 tralian formation is now well established as being Upper Triassic. . . . The 

 presence of lepidodendroid stems - in the Burghersdorp Beds is interesting as 

 showing we have here surviving one of the typical Paleozoic types.' 



This reference to Lepidodendron-stejns is probably based upon 

 specimens from Aliwal ^s^orth, which, although presenting a super- 

 ficial resemblance to such stems, are more likely to be gymno- 

 spermous, as pointed out in the description of a fossil for which 

 the name Strobilites laxus is suggested.^ Mr. Du Toit continues : — 



' The evidence of the plants of the Molteno Beds points to their being of 

 Rhaetic age,^ which thus confirms the view that the Burghersdorp Beds are 

 Upper Triassic. The Molteno Beds may thus be the equivalent of the 

 Wianamatta Series of New South Wales.' 



For further information in regard to the stratigraphy of the 

 rocks from which the plants were collected, reference should be 

 made to the Annual Eeports of the Geological Commission of the 

 Cape of Good Hope, and more particularly to the accounts of 

 surveys by Mr. Du Toit, in which mention is made of the several 

 localities where the plant-yielding beds have been examined.' It 

 would seem that the boundary between the Burghersdorp and the 

 Molteno Beds is not always clearly defined : a comparison of the two 

 fioras is made in the concluding section of this paper (pp. 104-105), 

 from which it will appear that certain species are common to both 

 horizons. 



Mr. Du Toit has drawn my attention to the occurrence of a zone 

 of transition between the Molteno and the Burghersdorp Beds, 



A. L. Du Toit (05) pp. 81-82. '^ See p. 100 of the present paper. 

 * Seward (03). ' A. L. Du Toit (05) & (06). 



