66 
THE TANGANYIKA PROBLEM. 
and to the south of it. Further north, on Tanganyika itself, 
these same deposits reappear and seem to cross the lake 
diagonally, and are found in association with beds similar to 
the Drummond series at Masswa south of Ujiji. They 
then continue with little interruption almost to the north ot 
the lake, the tilted conglomerates and shales of the series 
forming the crests of some of the high mountains which 
flank Tanganyika on the east between Ujiji and Usambura. 
The massive stratified beds which appear along the north- 
east coast of Tanganyika are also unquestionably the same 
series of formations as the stratified beds first seen further 
north and east by Speke, and more latterly encountered 
by Mr. Scott Elliot west of the Victoria Nyanza. ( The 
Karagwe series of Gregory.) 
Passing far to the west, beds which almost unquestionably 
belong to this series have been found by Cornet on the 
Lualaba and the upper tributaries of the Congo. 
It may be said, therefore, that there are vast aqueous 
deposits in the African interior (the Old African sand- 
stones), which are of enormous thickness, and which 
there is reason to believe are actually continuous through- 
out an area as large as the whole Australian continent (see 
map, facing p. 75). They occur most extensively to the 
west of the Great Central Range, and, judging from their 
great thickness, from their obviously aqueous origin, and 
from their vast superficial extent, it would appear probable 
that these sandstones are to be regarded as of marine 
origin. They are very possibly similar to the coast beds 
of sandstone which occur in the Taru desert west of 
Mombasa, and it is quite likely that they are actually con- 
tinuous with the sandstones of the north of the province 
of Mozambique, which occur in association with coal at 
Pemba. At any rate, and beyond question they show that a 
