430 NATURAL HISTORY OF AFRICA. 
Transition Limestone. 
The predominating rock of the Atlas range, as it 
passes through Tunis, Algiers, and Morocco, accord- 
ing to the acounts of travellers, is a limestone hav- 
ing the characters of that denominated transition. 
It exhibits variegated colours, and in some places is 
quarried as a marble, for the Numidic yellow, and 
variegated marbles, so highly prized by the an- 
cients, were dug in this great range of mountains. 
In the preceding list, we have enumerated gra- 
nites, syenites, porphyries, serpentines, &c. ; but 
the descriptions of their geognostic relations given 
by travellers are so imperfect, that we cannot ven- 
ture to determine how many of the varieties be- 
long to the primitive, and how many to "the tran- 
sition classes of rocks. 
Flcelz Rocks. 
Sandstone. 
This rock occurs in great abundance in many re- 
gions in Africa, as in the mountains leading to 
Cosseir, at Tetuan in Fez, Tunis, the peninsula of 
the Cape of Good Hope, and forming great moun- 
tains, reaching to a height of ten thousand feet to 
the northward of the Cape of Good Hope. At 
Tetuan it is said to rest upon granite ; in many of 
the mountain ranges in Southern Africa, upon 
clay slate or granite. It passes into a grey co- 
