432 NATURAL HISTORY OF AFRICA. 
where it contains petrified fishes, and it is men- 
tioned as occurring in the vicinity of Carthage. 
Gypsum, 
This floetz rock occurs within three leagues of 
Cosseir, where it is connected with limestone, and 
probably also with porphyry ; and it is mentioned 
as having been found in the valley of Egarement, 
associated with rock salt. 
Salt. 
This mineral occurs in vast quantities in Northern 
Africa, on both sides of the Atlas mountains. Mr 
Horneman, in his journey from Cairo to Ummeso- 
gier, discovered a plain on a limestone range, which 
bounds the desert of Libya to the north, consisting 
of a mass of rock salt, spread over so large a tract 
of surface, that in one direction no eye could reach 
its termination, and its width he computed at se- 
veral miles. To the south-east of Abyssinia there 
is a plain of salt four days' journey across, whence 
all that country is supplied. In the valley of 
Egarement there are beds of salt resting upon 
gypsum. At Tegazza, and in several other places in 
Sahara, large beds of very pure rock salt occur un- 
der strata of different kinds of solid rock ; and 
beds of salt appear in Darfur. Salt is also ob- 
tained in quantity from salt lakes of Domboo, 
from similar lakes in Southern Africa, and it is 
7 
