25() KAUKOO KOCKS I>' THE MAFUNGABUSI. 



fallin<^' boulders in lite talus of the basalt. Such masking' is 

 the case on the C^hidomwe Pass and on tlie Masasoni-Sikonyaiila 

 l^ath, thoug'h it is fairly conchisivei that the basalt is divided 

 into two sheets in these localities. 



These sheets are the extension of that known as the 

 Sikonyaula (2, p. 270, also 5, p. 49) to the west of the area 

 nnder discussion. The ai)])roximate thickness of the first and 

 second basalts, includin<)' the sandstones (11) is there 250 feet 

 — figures whicli nearly ag'ree with the a])pr()xiniate thickness 

 in the country to the north-west of Bnlawayo around 

 Nyamandhlovu. 



It is not jjossible to say whether this area of basalt 

 connected at any time with that at ISTyamandhlovu, to be 

 subsequently separated by the erosion of the Shanwani and 

 (iwelo rivers. Mnch of the country between the two reg"ions 

 is covered by later Kalahari sand, which hides the formations 

 on whicli it rests. 



The transition sandstone, immediately nnderlying- the 

 basalt, corresponds with that occnrring- to the north-west of 

 Bulawayo in its false bedding-, small percentage of intei'stitial 

 cement and rounded nature of the sand grains. It shows at 

 places extensive shatter belts, subsequently silicified, so that 

 the rock has a network appearance. Eeticulate ])atches are a 

 common featnre in these rocks, and have been noted at Pasinas 

 (5, p. 44), Tuli (1, p. 274), and Gwampa (1, ]). 278). 



Tlie Forest Sandstone is represented by the upper 

 (siliceous) division (Uily, the lower (c-alcareous) division not 

 having- been seen. The number of residuary rods and kernels 

 of silica lying- on the surface is very noticeable and helps in 

 demarking- boundaries. The g-roup includes an unsorted g-ritty 

 and pebble la^'er below Kadoma Hill. Tlie thickness does not 

 exceed 100 feet, while at Pasipas it is about 70 feet. 



The Esearpment Grits form larg-e red flat-topped hills or 

 minor escarpments from wliich the Forest sandstone lias been 

 removed. They include larg-e areas of pebble cong-lomerate, 

 flag'g-y sandstone and red g-rits, and immediately overlie the 

 Matabola or Madumabisa shales. Pellets of clay are frequently 

 included in the sandstone. Their minimum thickness is 

 100 feet, but i)robably some incoherent and overlying' beds 

 have been washed away. Mr. Liglitfoot (3) g-ives the fig-ure 

 of 300 feet as the thickness at Wankie. 



The Maduinahisa Shales of Lig-htfoot have so much in 

 common with the Matabola beds of the writer that there need 

 be no hesitation in ajjplying- the former term to the beds 

 underlying- the Escari)nient g-rit. One notable feature, how- 

 ever, is tlie local absence of nodules of lime, but in the 

 concretions of iron that are probably limestones replaced by 

 metasomatosis, tlie g-ypsum, the buff and g-rey sliales, and tlio 

 presence of thin impure coal beds the evidence seems to be 



