GHARDAIA. 39 



in the most thickly planted portions, one finds a veritable jungle in which 

 the desert glare is softened by the spreading tops of the palms and by the 

 close canopy of grape-vines which reach from one palm-stem to another. 

 There is a second story of apricots, peaches, almonds, and figs, and on the 

 floor one finds a variety of vegetables. Outside of the palm gardens, and 

 adjacent to them, are the plots in which cereals are grown. These gardens 

 are divided into diminutive fields, frequently not larger than 1 by 1.5 meters, 

 which are separated by small irrigating ditches and smaller laterals, from 

 which they are given water (fig. 19). Here barley, oats, and wheat are 

 raised, and often with them are planted carrots, turnips, or other vegetables. 

 The main ditches are rendered impermeable by heavy coats of plaster, 

 making it possible to use with the least waste the difficultly acquired water. 



THE PLAIN (HAMADA) OF GHARDAIA. 



A superficial view of the plain (hamada) which lies both to the north 

 and to the south of the M'Zab Valley does not suggest any vegetation 

 whatever, at least during the dry season. The desert is quite as barren in 

 appearance, as, for example, portions of the Libyan Desert are in reality. 

 In every direction one sees grayish-brown stones and bowlders, with little 

 earth, and in some places blackened stones, blackened by "fires from 

 heaven" the Arabs believe, but nothing to indicate the presence of plants. 

 Tristram has described the plain as "one mass of naked rock, rough stone, 

 and coarse debris, from the neighboring mountain, but without a scrap of 

 earth or a vestige of the minutest vegetation." But close study of the 

 plain makes out a better case than this; in fact, where the soil has accumu- 

 lated in pockets, where there is a slight drainage depression, or where 

 spaces between the rocks are filled with soil, careful examination shows the 

 remains of annuals and not a few living perennials; but like other intense 

 deserts, plants, even when relatively numerous, are not present in sufficient 

 numbers and not of sufficient size to give character to the landscape or 

 to hide the surface of the ground. 



The plain on both sides of the valley was studied and a few areas care- 

 fully examined with results which are summarized in the following para- 

 graphs. 



It has already been mentioned that the walls of the M'Zab Valley at 

 Ghardaia are precipitous, rising between 60 and 100 meters from the valley 

 floor, their summits being the general level of the plain. Both to the north 

 and to the south of the valley there are short but steep tributary gulches. 

 In these gulches, and especially at the heads of the gulches, are pockets 

 filled with earth, and here may be found some perennial vegetation. For 

 example, at the head of such a ravine, 3 kilometers north of the valley, 10 

 undetermined living species were found, of which 6 were perennials and the 

 balance were long-lived annuals or biennials. (See fig. 20.) In an analogous 

 situation, but on the plain to the south of the valley, the aspect being sim- 



