PRIMITIVE ROCKS. 
along the west side of the Red Sea, where it ap- 
pears to be contained in a clay slate, which alter, 
nates with beds of compact felspar. It is erro- 
neously described by some authors as a green 
coloured marble* 
10. Marble, or Foliated Granular Limestone, 
Beds of this rock, of a white, grey, yellow, 
bluish, and red colour, occur in clay slate, and 
also in serpentine, in Upper Egypt, Darfur, and 
Abyssinia. In these countries it is occasionally 
intermixed with serpentine, forming the well 
known compound rock named verde antico. The 
predominating rock of the Atlas range as it passes 
through Tunis, Algiers, and Morocco, is a lime- 
stone, which exhibits many and often beautiful 
colours. The Numidic yellow, and many of the 
variegated marbles prized by the ancients, were 
dug in this range of mountains. 
11. Conglomerate, named also Breccia di Verde. 
This conglomerated looking rock occurs in 
beds of great thickness and extent, along with 
clay slate, in the ranges of mountains that extend 
towards Cosseir, It is remarked, that as we ap- 
proach Cosseir three sets of rocks succeed each 
other : the first set is small, granular, and grani- 
tic ; the second set is of the breccia di verde 5 
