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MESSRS. A. R. ANDREW AND T. E. G. BAILEY [May I9IO, 



western by a nameless ridge which separates it from the north-and- 

 south limb of the Rukuru River. To this ridge we shall refer in 



future as the Ru- 



Fig. 4.- 



-Karroo and lacustrine beds of the 

 Mpata area. 



kuru Ridge. The 

 Karroo deposits oc- 

 cupying this district 

 lie in a broad valley- 

 depression, and are 

 bounded _on three 

 sides by lines of fault 

 which bring down 

 the sedimentarj' de- 

 posits against the 

 gneiss. On the 

 south - west, how - 

 ever, the junction 

 with the gneiss is 

 a normal one, and 

 is marked by the 

 occurrence of a 

 boulder - conglome - 

 rate and a distinct 

 overlap of the newer 

 beds upon the older 

 crystalline rocks. 

 The general strike 

 of the Karroo Series 

 is, as before, in a 

 north-and-south di- 

 rection ; and the 

 beds, although some- 

 what folded, dip as 

 a whole eastwards 

 at an average angle 

 of about 10°. 



The Karroo Beds 

 fall into the usual 

 three divisions, and 

 are exposed as fol- 

 lows : — 

 Upper Division. 



5. Calcareous Group, consisting of mudstones interbedded'with 



thinly-bedded argillaceous, sometimes oolitic limestones. Minimum 



thickness = 700 feet. 



4. Purple Sandstones and Shales, containing calcareous seams 

 and concretions, just as in the similarly placed beds of the Nkana 

 area. Thickness = about 500 feet. 



3. Upper Sandstones, or Grits and Conglomerates, con- 

 sisting of pebbly felspathic sandstones, with conglomerates and 

 occasional flaggy bands. Thickness = about 500 feet. 



[.Scale: 1 inch 



=, 3 Miles J Jj?\ 



Ficasa 



[Calcareous Series 



[ ---J Purple Sandstone and 



Shale, wJth Conglomerate. 



I Upper Sandstones. 



Faults 



Lower 

 Sandstones. 



Alluvium. 



Shale Group 



|oooof° |L - 



