Modern Terrains of Tigrinyaland and Semien — Part 1

We have included in modern terrains, a set of deposits formed:

1. By madrepores and shells;
2. By travertine limestone;
3. By clayey-sandy or stony alluvium, sometimes saliferous.

Some are produced in the waters of the sea; others are produced by those of rivers, lakes and by the melting of snow; others finally from mineral springs.

The shores of the Red Sea, in the vicinity of Mitsiwah, present a series of deposits which are composed of shells and madrepores more or less mixed with sand and clay. These deposits, which also contain fibrous gypsum, form a small ridge which currently separates the sea from the clayey-sandy alluvium of the southwest. Among the shells which compose these rocks, we will cite the following (for a detailed description of the below listed species, refer to Lamarck’s Système des Animaux sans Vertèbres¹ and Animaux sans Vertèbres², to Brocchi’s Conchiologia Fossile³, to Gmelin’s Systema Naturae per Regna Tria Naturae⁴, and to Sowerby’s Conchological Manual⁵):

• Solarium perspectivum, Lamarck.
• Rostellaria curvirostris, Lamarck.
• Strombus gibberulus, Lamarck.
• Terebra flamea, Lamarck.
• Conus aldovrandi, Brocchi.
• Conus virginalis, Brocchi.
• Voluta coronata, Brocchi.
• Ostrea imbricata, Lamarck.
• Tridacna squamosa, Lamarck.
• Cardita intermedia, Lamarck.
• Venus rugosa, Gmelin.
• Cardium rugosum, Lamarck.
• Arca diluvii, Lamarck.
• Pectunculus, Lamarck.

The shell deposits of which we speak are not limited to the environs of Mitsiwah. For they give rise to different islands in the middle of the Red Sea, and constitute the present soil of a certain extent of the coasts of this sea, as of that of the Indian Ocean. We thus observe that the modern terrains are greatly developed in these regions, thanks to the shells and madrepores which live in these two above-mentioned seas.

This is the nineteenth installment of the geological description of Tigrinyaland⁶ and Semien⁷, which has been adapted from Messrs. Ferret and Galinier‘s work published in 1847⁸.

Reference Notes

1. Lamarck, Jean-Baptiste-Pierre-Antoine de Monet de (1801) Système des animaux sans vertèbres, ou tableau général des classes, des ordres et des genres de ces animaux; présentant leurs caractères essentiels et leur distribution, d’après la considération de leurs… Detreville: Paris. ↩︎
2. Lamarck, Jean-Baptiste-Pierre-Antoine de Monet de (1815–22) Histoire naturelle des animaux sans vertèbres: présentant les caractères généraux et particuliers de ces animaux, leur distribution, leurs classes, leurs familles, leurs genres, et la citation des principales espèces qui s’y rapportent… En sept tomi (avec le tome six en deux parties). Verdière: Paris. ↩︎
3. Brocchi, Giambattista (1814) Conchiologia fossile subapennina con osservazioni geologiche sugli Apennini e sul suolo adiacente. In due tomi. Stamperia Reale: Milano. ↩︎
4. Gmelin, Johann Friedrich et al. (1788-1793) Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. V.1 Pt.1-7, V.2 Pt.1-2, V.3. Impensis Georg. Emanuel. Beer: Lipsiae [Leipzig]. ↩︎
5. Sowerby, George Brettingham (1839) A Conchological Manual. G.B. SOWERBY: London. ↩︎
6. 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. ↩︎
7. 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. ↩︎
8. 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. ↩︎