486 SIR RODERICK MURCHISON’S ADDRESS, [chap, xviii. 
this vast interior is entirely exempt from the coarse 
superficial drift that encumbers so many countries, as 
derived from lofty mountain-chains from which either 
glaciers or great torrential streams have descended. 
In this respect, it is also equally unlike those plains of 
Germany, Poland, and Northern Russia, which were 
sea-bottoms when floating icebergs melted and dropped 
the loads of stone which they were transporting from 
Scandinavia and Lapland. 
“ In truth, therefore, the inner portion of Southern 
Africa is, in this respect, as far as I know, geologically 
unique in the long conservation of ancient terrestrial 
conditions. This inference is further supported by the 
concomitant absence, throughout the larger portion of 
all this vast area, i.e. south of the Equator, of any 
of those volcanic rocks which are so often associated 
with oscillations of the terra Jirma * 
“ With the exception of the true volcanic hills of the 
Cameroons recently described by Burton, on the west 
coast, a little to the north of the Equator, and which 
possibly may advance southwards towards the Gaboon 
country, nothing is known of the presence of any 
similar foci of sub-aerial eruption all round the coasts 
of Africa south of the Equator. If the elements for 
the production of them had existed, the coast-line is 
precisely that on which we should expect to find such 
volcanic vents, if we judge by the analogy of all 
volcanic regions where the habitual igneous eruptions 
are not distant from the sea, or from great internal 
masses of water. The absence, then, both on the coasts 
and in the interior, of any eruptive rocks which can 
have been thrown up under the atmosphere since the 
period when the tertiary rocks began to be accumulated, 
is in concurrence with all the physical data as yet 
got together. These demonstrate that, although the 
geologist finds here none of those characters of litholo- 
* “ Although Kilimandjaro is to a great extent igneous and vol¬ 
canic, there is nothing to prove that it has been in activity during 
the historic era.” 
