Kariba biotite gneiss at the Nyanyana bridge foundation overlain by basal red mudstone of the Lower Karoo Group. 

 

The Nyanyana River bridge, crossed just prior to passing the turnoff to Kariba Airport, is founded on strongly foliated and folded biotite gneiss.  The basal unit to the Karoo Supergroup, as in adjacent parts of Zambia, is a red mudstone with basal conglomerate in places.  This mudstone is seen in direct contact with the Kariba gneiss both downstream of the bridge where they are overlain by a thick sequence of grey Madumabisa Mudstone beyond, and in the tributary upstream of the bridge. Large boulders of siliceous breccia from the Nyanyana Fault can be seen as boulders in the riverbed.    

 

Stop 6 on the attached filed guide