52 BOTANICAL FEATURES OF THE ALGERIAN SAHARA. 



The relation of the Chott Mellala to the country to the north or the south 

 was not seen, but between it and Ouargla there lies a succession of smaller 

 and more irregular chotts, which together form a fairly well-connected 

 chain. These chotts are separated by low passes and flat-topped hills 

 whose summits are on a level with the neighboring plain. Many of the 

 hills are cone-shaped and in other topographic features the region shows 

 the eroding action of wind. About 7 kilometers from Ouargla an opening 

 in the mamelons gives a view of a plain extending on a lower level to the 

 horizon. This is the reg, or fluvial desert. The Ouargla plain, or reg, is 

 connected with the drainage of the great Oued Ighaghar and has a char- 

 acter which in many ways is different from the Gantara, over which we 

 had just passed. 



With the descent to the reg desert a more monotonous region is en- 

 countered. In the vicinity of Ouargla and for some kilometers to the north 

 the topography is quite flat and gives the impression of a flood-plain. To 

 the east it stretches unbroken to the horizon, but to the west it is bounded 

 by a fairly abrupt wall, the Gantara escarpment. At intervals of several 

 kilometers low sand ridges cross the route over the plain, and on the second 

 day somewhat higher ground was traversed and a sand ridge about 4 kilo- 

 meters across was encountered. The country then becomes somewhat 

 more broken and presents the appearance of being the remains of an ancient 

 and more elevated plain. About 56 kilometers from Ouargla are the largest 

 dunes crossed; where traversed, these were 10 kilometers from north to 

 south and extended beyond our vision both to the east and the west. This 

 is apparently the edge of extensive dune regions which lie mainly east of 

 Touggourt and of the Oued Rirh. For possibly the last 30 kilometers of 

 the journey to Touggourt there are dunes and chotts in alternation. 



A word should be said regarding the hydrography of the region whose 

 surface features have been sketched above. Between the cities of Beni 

 M'Zab and Ouargla two wells were passed, although a route could have 

 been taken which could have included three wells. The wells are 125 meters 

 or less in depth and are maintained by the government for the benefit of 

 the caravans, as well as to provide water for the large number of goats 

 and sheep pastured in the neighborhood. The situations of the wells are 

 always in depressions, either along the Oued M'Zab or in similar although 

 smaller drainage areas, and none are on the Gantara. At Ouargla and on 

 the reg desert to the north of the town the water lies very close to the 

 surface of the ground. It can be dipped with buckets and the roots 

 of the palms reach to the water-table. The water from the shallow wells 

 is strongly impregnated with salts. Before reaching Touggourt standing 

 water was seen where the trail crossed certain chotts. Numerous artesian 

 wells have been made by the government which penetrate the ground 

 several hundred meters and give a large and continuous supply of sweet 

 water. 



