Vol. 65. j KARROO SYSTEM IN NORTHERN RHODESIA. 425 



and west and dips 45° southwards. One such piece, 3 feet across, 

 was honeycombed, by the removal of the matrix from between the 

 angular pebbles : an indication of how some of the mass may be 

 broken up. 



Other occurrences may be briefly noticed. Loose boulders and 

 blocks of conglomerate may be seen in the Gyuni Valley, on the 

 northern slopes of the Lupoposhwe divide, along a detached ridge 

 parallel with the range, but divided from the Archaean rocks by a 

 strike- valley 400 yards wide and 100 feet deep : this valley I 

 take to be due to erosion getting to work behind the strike of the 

 bed of conglomerate after the flat dome had been removed. This 

 point is about 3 miles distant from the Eakanunga outcrop, and the 

 intervening metamorphic ridge rises about 1000 feet — so that a 

 low angle would take the conglomerate over the anticline. 



In the Luano Basin, the coarse basal deposits occur also in a 

 brecciated type : — angular unsorted fragments of the contiguous 

 Archaean floor, almost as one may see them on the weathered 

 surface nowadays. At Impala Ridge a dome of mica-schist 

 emerges from the Karroo subsoil, and on its northern shoulder a 

 dark red breccia (4 feet thick) is covered by a whitish micaceous 

 clay, pipe-clays, and deep red ferruginous clay, breaking spherically 

 into rounded blocks, bleached white near crevices invaded by 

 tree-roots : these all dip 25° northwards. A similar breccia occurs 

 at the base of the coal-measures at Chisali-sali Hills : consisting 

 of unsorted fragments of the adjacent mica-schist, quartz-veins, 

 schorlaceous schist, and white mica. The overlying sediments are 

 tilted up, at an angle of 17°, against the metamorphic dome of 

 Chisali-sali. This brecciated form, or ' scree ' condition of the 

 basement of the Karroo System may be observed at many other 

 localities. 



South of the Kafue River have been found masses of con- 

 glomerate, lying at the base of the formation in extensive patches, 

 but seldom continuous for any great distance. In the Malembi 

 syncline on the Lufua River, there is a siliceous conglomerate, 

 with pebbles of angular quartz, and similar to the sharp fragments 

 of vitreous quartz left scattered on the surface by recent decay of 

 the schists. In the Chigalonti the contact is made by a 24-inch 

 bed of saccharoidal quartz-conglomerate in a ferruginous clayey 

 matrix ; but at short distances on either side this bed is replaced 

 by coal-measures, thus showing a very irregular floor. 



Character of the Conglomerate. — The coarse basement- 

 deposit of the Karroo seems to vary between an angular breccia 

 and a well-worn rounded puddingstone. The former is a compacted 

 mixture of fragments of mica-schist, angular vitreous quartz, and 

 grains of haematite — with irregular patches of chocolate-coloured, 

 sometimes greenish clay, and also of soft pellicles of sand. There 

 is no sorting, orientation, or rounding, and the accumulation 

 suggests a genesis similar to that of the weathering hill-sides of 



