62 
THE TANGANYIKA PROBLEM. 
described are a very striking series of formations, they are 
very similar to the sandstones and conglomerates which 
have been found south of the Zambesi in relation to 
the gold-bearing districts of Salisbury and Johannisburg. 
They are probably related to the extensive sandstone 
deposits which are said to occur north of the Zambesi 
in conjunction with coal areas, and they may possibly 
communicate directly with these deposits round the west 
and south of the Nyassa region. They are also similar and 
probably identical with the red sandstone and conglomerates 
which occur in an enormous series of deposits in the 
region of Tanganyika, Rukwa and Mwero. They were first 
observed by Joseph Thompson, and have often been quite 
erroneously spoken of as Karoo beds. 
Near Mount Waller some of the less upraised sheets of 
sandstone bear, as I have said, above them lake deposits 
of white chalky limestone, in which there are to be found 
the remains of the molluscs which now live in Nyassa. But 
between Karonga and Fort Hill there are encountered, 
resting unconformably on the old tilted red sandstones, 
masses of grey and blue stratified rock which are obviously 
of a different date and origin, and it was in these that 
Drummond found the remains of ganoid fish. These 
remains were examined by Professor Traquair and appear 
to be the fragments of four new polypteroids closely 
similar to several marine triassic forms. The fossil shells 
from the same beds were also new, and were not like the 
bivalves either of Nyassa or Tanganyika. They were 
examined by Professor Rupert Jones and regarded as 
probably estuarine forms. Between Nyassa and Tangan- 
yika in this region there are also modern lake deposits 
lying horizontally and unconformably over the tilted sand- 
stones and the similarly tilted Drummond series. 
