Triassic Terrain – Secondary Lands of Tigrinyaland and Semien

This is the tenth part of the geological description of Tigrinyaland¹ and Semien,² which has been adapted from Messrs. Ferret and Galinier‘s work published in 1847.³ In this installment, the secondary lands of Tigrinyaland and Semien composed of triassic terrains will be examined.

Based on the relative situation of the land, it is probable that part, if not all of the Triassic terrain, exists in Abyssinia,⁴ in the country of the Afars,⁵ to the west of the Tigray region, with even more reason that we find rock-salt accompanied by sulfur, in the middle of clays or marls which seem to relate to variegated sandstone or even to iridescent marls.

Rock-Salt

Rock-salt exists in the plain located around Ayehlé, Alaoul, Tselim-Tsebri, Rorom, Gera’e, Reget, etc. This plain extends at the foot of the eastern slope of the mountains which form the rim of the coasts of the Red Sea.

The Afars exploited the salt in the open air, and employed it for two uses: as food and as currency. The salt mines constituted the main wealth of the Afars, and enabled them to carry out a large trade in salt with the other Abyssinians.

It is to be remembered that salt was one of the articles which served as currency in medieval Abyssinia.⁶ Especially from Aderqay southwards, salt was the main medium of exchange in large purchases, such as sheep and cattle.⁷ To make it useable for monetary purposes, the rock-salt was cut into parallelepipeds about 20 centimetres long and 4 centimetres thick. Because of its fragility and solubility, it was not easy to use. People who had to accept it in payment for some object always claimed that it was too light and not the right size.

The rock-salt, which is white or reddish in color, is found bare in many parts of the Afar country, and seems to exist over a fairly large area. We were unable to penetrate this region, but we were able to obtain samples that were associated with clay or marl, and we learned that this salt was arranged in powerful layers. Now, as certain points of this immense salt-clay deposit lie towards the limit of the terrains of the Oolitic Group, in particular the Lias, it is highly probable that this salt belongs to the terrains of the Triassic Group.

Sulfur Mines

At Alaoul, on the first plateau of the mountains which are the extension of the Tarenta,⁸ and at the beginning of the plain which we have mentioned above, sulphur is exploited on the surface of the ground. This sulphur is associated with rock-salt, for we have seen many samples which combined the two minerals and which came from the locality. Thus the sulphur mines would be opened in the salt mines, that is to say in the Triassic terrain. We will not speak how the sulphur arrived there, whether it is by means of springs or vapours resulting from the extinct volcanoes which have spread almost everywhere in Abyssinia. For we have not explored the region, and we cannot enter here into theoretical speculations.

Reference Notes

1. Tigrinyaland was a collective name of the Midri-Bahri (modern-day state of Eritrea) and Tigray (the northernmost region of modern-day Ethiopia). The term employed for Tigrinyaland by Messrs. Ferret and Galinier in their book is “Tigré”, which had been the designation used by the Amhara rulers of Abyssinia to refer both to the Tigrinya people and the Tigrinyaland. ↩︎
2. Semien was historically the frontier province of the Tigrinya with the Amhara. However, since the reign of Emperor Susenyos, the province of Semien had been governed by members of the Amhara royalty and nobility. Following the death of Dejazmatch Sabagadis in 1831, Semien under its Amhara ruler Dejazmatch Wubbe turned from the frontier province of the Tigrinyaland to the power-center of the Tigrinyaland. This continued until the rise of Emperor Tewodros in 1855. ↩︎
3. Ferret, Pierre Victor Adolphe et Galinier, Joseph Germain (1847) Description Géologique du Tigré et du Samen. Voyage en Abyssinie dans les provinces du tigre, du samen et de L’amhara. Tome troisième. Paulin: Paris. ↩︎
4. Abyssinia is a reference to the region which encompasses the modern-day states of Ethiopia, Eritrea, Djibouti, parts of Sudan and parts of Somalia. ↩︎
5. In their book, Messrs. Ferret and Galinier use the term “Taltal” to refer to the people of Afar. The word “Taltal” was previously used by other Abyssinians to refer to the Afar people while the term “Afar” was used to designate the region they inhabit. “Afar” is the adjective form of the word “afer” and translates into “dusty”, “soily”, and accurately describes the dusty nature of the desert and semidesert landscape of the region. However, since the Afar people themselves prefer to be called “Afar”, I have replaced everywhere the term “Taltal” by the word “Afar”. ↩︎
6. Combes, Edmond et Tamisier, Maurice (1838) Voyage en Abyssinie: dans le pays des Galla, de Choa et d’Ifat; précédé d’une excursion dans l’Arabie-Heureuse, et accompagné d’une carte de ces diverses contrées; 1835-1837. Tome IV. Pag. 108. Louis Desessart: Paris. ↩︎
7. Bruce, James (1790) Travels to Discover the Source of the Nile, In the Years 1768, 1769, 1770, 1771, 1772, and 1773. Volume III. p.192. J. Ruthven: Edinburgh. ↩︎
8. The Tarenta mountain range forms the eastern escarpement of modern-day eritrea, and looks down on the Eritrean eastern lowlands which are close to the Red Sea. ↩︎