Introduction to the Geological Description of Tigrinyaland and Semien

This is adapted from the geological description of Tigrinyaland and Samen by Messrs. Ferret and Galinier.¹ The French explorers Messrs. Ferret and Galinier entered Northern Abyssinia via Massawa on October 30, 1840 and lived there for almost two years until August 20, 1842. During their stay, they undertook different scientific investigations in several districts of Tigrinyaland,² Semien,³ Wégéra, Gondar, the Eastern shore of Lake Tsana, etc. They managed to travel as far as 12 degrees north latitude in Abyssinia. After their return to France, in 1847 they published a book in three volumes, which details their experiences and scientific findings of Northern Abyssinia.⁴ What follows is the introduction part of their report findings on the geological makeup of Tigrinyaland and Semien, which gives a brief summary of their observations about Abyssinia and the geological methods they employed.

Abyssinia⁵ is a very rugged country. Nature, in fact, seems to have brought together in this part of Africa everything that is imposing and picturesque: high mountains, deep valleys, large freshwater lakes, plateaus of admirable fertility, an infinity of rivers and torrents which, on stormy days, form a thousand waterfalls and rush foaming in all directions. Such is generally the landscape which unfolds before the eyes of the traveler as he advances in this magnificent country.

As there is always a reciprocal dependence between the relief of the soil and the rocks which compose it, we can conclude a priori from the complex orography⁶ of Abyssinia that this country is very remarkable in terms of its geological constitution. The details which follow will prove this truth. They will also demonstrate the intimate connection of the variety of terrain with the variety of agricultural production or mineral wealth found there. If this work of ours is incomplete, if it lacks development or precision, we dare at least hope that it will not be without interest for the geologist, and that it will give an overview of the advantages that can be obtained from Abyssinia.

We did not have a long enough stay in the northern provinces of Ethiopia to be able to describe exactly all the lands and all the mineral riches they contain. However, by means of the cross-sections, maps, itineraries and numerous observations made by us, we were convinced that, even if Abyssinia does not offer the geologist the complete series of terrains, it presents at least a large number of them, and that it must be ranked among the most complex and most remarkable regions of the world from a geological point of view. The lands that we have recognized in Abyssinia are included from the first to the last degree of the geological scale. Thus we found the primary and intermediate (or transitional) terrains in the country of the Sahos, in Tigray, etc; secondary lands, on the border of Tigray and the country of the Afars; tertiary and modern terrains, on the banks of the Red Sea, in Tigray,⁷ in Semien, Shiré, etc. And, by adding to the extent of this geological scale a wide variety of sedimentary rocks, plutonic⁸ and volcanic rocks, rocks commonly called metamorphic,⁹ a considerable quantity of extinct volcanoes, thermal springs, deposits of iron ores, sulfur, rock-salt, fuels, malachite,¹⁰ etc, we will have a general idea of the geological importance of Abyssinia.

In this work of ours, we have adopted two classifications for the description of land:

1. the large division into primary terrain, intermediate (or transitional) terrain, secondary terrain, tertiary terrain and modern terrain;
2. With regard to the subdivisions of the above lands, the classification of the lands of Mr. Rivière, as he exposed it in his Eléments de géologie published in 1839.¹¹

We did not think it necessary to push the divisions of the lands of Abyssinia any further, so as not to expose ourselves to errors by wanting to bring too rigorous accuracy to our work. Moreover, we did not forget that the main goal of our travel was not the geological study of the countries we were to visit, and moreover, even the descriptions of extremely remote areas of geologically very well-known countries always present great difficulties.

As an overview, we will say that the primary and intermediate terrains constitute the base of the soil of Abyssinia, and that they are often crowned by tertiary plateaus, cut here and there in the form of natural fortifications, and on which Usually volcanic cones or domes rise. We see the primary and intermediate terrains in the vicinity of the Red sea, at the base as well as at the top of the mountains parallel to the coast, in the bottom of the valleys of central Abyssinia and on the jagged or rounded mountains of this vast region. These generally form the fertile soil of Abyssinia. Then, in the eastern part of this country, the secondary lands extend successively towards the Indian Ocean, that is to say the Liassic, Oolitic, Triassic and Carboniferous or Anthraxiferous terrains.¹² Thirdly, the Cretaceous terrains,¹³ which form the upper part of the secondary lands and which appear on a large scale around the Mediterranean, seem to constitute the soil of the region located towards Shoa, and even of that which borders Caffa. Finally, the tertiary terrains form, as we have already said, the plateaus of central Abyssinia; while modern terrains are very developed on certain points of the coasts and islands of the Red Sea.

In the next part of this article, the primary lands of Tigrinyaland and Semien identified by Messrs. Ferret and Galinier will be discussed.

Reference Notes

1. 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. ↩︎
2. 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. ↩︎
3. 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. ↩︎
4. Ferret, Pierre Victor Adolphe et Galinier, Joseph Germain (1847) Voyage en Abyssinie dans les provinces du tigre, du samen et de L’amhara. Paulin: Paris. ↩︎
5. Abyssinia is a reference to the region which encompasses modern-day Ethiopia, Eritrea, Djibouti, parts of Sudan and parts of Somalia. ↩︎
6. Orography is the science of mountains. ↩︎
7. Here the reference is to the district of Tigray, which has been historically the epicenter of Tigrinyaland and has given its name to the whole Tigray region. It is bounded on the north by the River Mareb, on the east by the district of Agame, on the west by the district of Shire, and on the south by the River Wari. ↩︎
8. Plutonic rock is rock formed by solidification from a molten state beneath the earth’s surface, especially from molten magma. ↩︎
9. Metamorphic rock is a rock that has been changed from its original form by heat and/or pressure. ↩︎
10. Malachite is a green or blue mineral used as an ore of copper and for making ornamental objects. ↩︎
11. Rivière, Alphonse (1839) Eléments de Géologie pure et appliquée ou Résumé d’un cours de géologie descriptive, spéculative, industrielle et comparative. Méquignon-Rivière: Paris. ↩︎
12. For a detailed description of liassic, oolitic, triassic and Carboniferous or Anthraciferous terrains, refer to the book “Eléments de Géologie pure et appliquée ou Résumé d’un cours de géologie descriptive, spéculative, industrielle et comparative” by Alphonse Rivière, published in 1839. ↩︎
13. For a detailed description of cretaceous terrains, refer to the book “Eléments de Géologie pure et appliquée ou Résumé d’un cours de géologie descriptive, spéculative, industrielle et comparative” by Alphonse Rivière, published in 1839. ↩︎