Chaîne Du Thaljah

The Chaîne du Thaljah is a range of mountains in the

Gafsa Governorate Gafsa Governorate ( ') is one of the 24 governorates of Tunisia. It is situated in central Tunisia, bordering Algeria. It covers an area of 7807 km2 and has a population of 337,331 (2014 census).Gafsa Gafsa ( aeb, ڨفصة '; ar, قفصة qafṣah), originally called Capsa in Latin, is the capital of Gafsa Governorate of Tunisia. It lends its Latin name to the Mesolithic Capsian culture. With a population of 111,170, Gafsa is the ninth-la ...

in Tunisia to

Negrine Negrine is a town and commune in Tébessa Province in north-eastern Algeria. It was the site of ancient Casae Nigrae, a settlement of Roman North Africa with an attached bishopric that remains a Latin Catholic titular see. Geography Negrine i ...

in Algeria, crossing the border not far from the small oasis of

Tamerza Tamerza (or Tameghza, تمغزة) is th largest mountain oasis in Tunisia, known as '' Ad Turres'' by the Romans. It has a canyon and an abandoned old town. The town was abandoned after the river flooded for 22 days in 1969. It is located north ...

. The highest point is the Jebel-Bliji. On the north side, at a place called Es Safia south-southeast of

, a rock painting was found on an overhanging rock wall at the entrance of a deep ravine. It depicts animals and men in silhouette, in blood on a yellow-ochre background, all slightly glazed. It was probably made by Berbers between the Stone and Bronze Ages. In 1885–86 the geologist

Philippe Thomas Philippe Thomas (4 May 1843 – 12 February 1910) was a French veterinarian and amateur geologist who discovered large deposits of phosphates in Tunisia. Despite the huge economic importance of his discovery, he received little recognition during ...

explored the southern area of Tunisia between the meridian of

Kairouan Kairouan (, ), also spelled El Qayrawān or Kairwan ( ar, ٱلْقَيْرَوَان, al-Qayrawān , aeb, script=Latn, Qeirwān ), is the capital of the Kairouan Governorate in Tunisia and a UNESCO World Heritage Site. The city was founded by th ...

and the Saharan

chott In geology, a chott, shott, or shatt (; ar, شط, šaṭṭ, lit=bank, coast) is a salt lake in Africa's Maghreb that stays dry for much of the year but receives some water in the winter. The elevation of a chott surface is controlled by the pos ...

s, covering a vast area. He also explored the western area, which his colleagues had neglected, particularly the Chaîne du Thaljah or Chaîne du Tseldja mountains that stretch westward from

Gafsa Gafsa ( aeb, ڨفصة '; ar, قفصة qafṣah), originally called Capsa in Latin, is the capital of Gafsa Governorate of Tunisia. It lends its Latin name to the Mesolithic Capsian culture. With a population of 111,170, Gafsa is the ninth-la ...

into Algeria. He identified the geology of the Gafsa chain with that of the M'fatah massif in Algeria and on 18 April 1885 found phosphates at Jebel Tselja. Thomas observed that at the junction of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

limestone axis of the chain with its

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

foundations there was a dark

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

and a brown or greenish-gray limestone with a tricalcium phosphate content that averaged 60%. This was found where the Jebel Tseldja opens into the plain at Fous-Tseldja, near

Métlaoui Métlaoui ( aeb, متلوي ') is a town and commune in the Gafsa Governorate, Tunisia. In 2014 it had a population of 38,634.Mountain ranges of Tunisia