426 ME. A. J. C. MOLTNETJX^ON THE [Aug. 1909, 



the present day, where the schists rot for a considerable distance 

 down. This primitive form is not thick, and may represent a laud- 

 surface. 



Between this and the mature typical puddingstones there are 

 many intermediate degrees of angularity, disposition of matrix, aud 

 arrangement. The Eakanunga type is rufous in colour, and shows 

 remarkable diversity in short distances. Generally, the boulders 

 lie without regard to size, and may be pressed close together with 

 no interstitial matter, or separated by much matrix of varying 

 fineness. The matrix changes in a few inches from angular grit 

 to clay, while opaline silica (chalcedony) appears west of Chigona, 

 making the rock extremely stubborn under hammer-blows : but 

 it is rapidly reduced and softens on exposure. When tbe coarse 

 matrix comes into contact with a pebble, the grains also become 

 smooth on the contact-face. Among the pebbles there is an 

 occasional semblance of orientation, with lenticles of hard 

 false-bedded grit or fissile micaceous sand. The stones vary in 

 size from peas to boulders of 40 inches, and consist almost solely of 

 quartz and quartzite, partaking of the nature of the contiguous 

 pre-Karroo rocks. Thus pebbles of banded ferruginous quartzite, 

 schorlaceous rock, quartz with tourmaline, and saccharoidal quartz- 

 ites, are all fouDd near where those masses occur ; while aloug the 

 Formoshi range, which is of dolomitic schist, occur the interlaced 

 quartz-prisms that originated from vughs therein. 



It is noteworthy that fragments of gneiss, schist, dolomite, or 

 limestone do not occur in any conglomerates where the pebbles are 

 well rounded — only in the deposits that are brecciated, uneven, 

 and show no evidence of internal movement. Some of these blocks 

 would be removed in solution, while the gneiss and schist rapidly 

 suffer disintegration under atmospheric waters. In a well suuk 

 through a talus-sheet containing these rocks, the gneiss was found 

 to be so soft that a penknife could be thrust iuto it. If therefore 

 detritus of these yielding rocks were subject to pressure, the removal 

 of the one description in solution, and the softening of the other, 

 would cause such contraction in bulk that some movement would 

 arise from that cause alone. If other forces were also at work, 

 there would be increased grinding of the pebbles one against 

 the other. In this manner the resistiug quartzite-bands and vein- 

 quartz would remain to form the pebbles, which would be pushed 

 against each other, the nose of one into the side of the other, just as 

 the Eakanunga conglomerate shows them now, and thus would be 

 brought about the concave depressions that are to be found on 

 every pebble. 



Many boulders have a flattened surface or ' sole.'' One was seen 

 to have two flutings 4 inches apart between the crests and 

 an inch and a half deep, running diagonally across the cleavage of 

 the quartzite. Another block of 18 inches, otherwise angular, had 

 a face for its whole length and breadth that was slightly concave 

 aud had sharp edges, and an egg-shaped one at Rutente had been 

 cleanly cut across the end. These characteristics may all be 



