Somalia Geology and Climate

By | December 15, 2021

Geology. – Geologically, the Somali plateau has a predominantly sedimentary character. The ancient crystalline rocks – granites and crystalline schists of the Inda Ad series – which form the base of the plateau, emerge at times along the coast of the Gulf of Aden: in the hinterland of Zeila and Berbera up to the pass of Meraia (Miriya) and then between Heis and Elaia in British Somalia, and in small strips at Bender Cassim and Ras Hantara in Northern Italian Somalia; around Harar and then south of this city in the bottom of the Errer, Dacato, Fafan and Gerèr valleys, erosion also returns to discover the crystalline rocks; which finally emerge from the eluvial blanket in the form of rocky spikes, in the area of ​​the bur in Southern Italian Somalia. On this crystalline base rests a series of layers of varicolored sandstone with gypsum, referable to the Triassic and Jurassic periods (Lugh sandstones) emerging precisely around Lugh and then for long stretches in the valleys of Ganale Doria and Uebi Gestro and in those Uebi Scebeli between Imi and Bulo Burti, and also in the valleys south of Harar and in some parts of British and Italian Northern Somalia. The Middle and Upper Jurassic is represented by marly limestones (Bardera series) richly fossiliferous with Ammonites and Brachiopods, very widely extended in the plateaus west of the 45th meridian, between Harar and Bardera; minor flaps are observed in Bio Caboba in Abyssinian territory and then towards the Gulf of Aden in Meregalleh, in Colon, in Bihendula, in Las Gorè, in British territory.

The Cretaceous period is represented by two facies: an arenaceous facies and a limestone facies. The continental or coastal facies, of varicolored sandstones with gypsum of the Nubian sandstone type, is extended especially in the Oltregiuba (sandstones of the Merehàn) in vast strips in British Somalia (sandstones of Dubar) and in a long band crossing the peninsula obliquely from Dauenle in French territory and then from Bio Caboba, parallel to the left bank of the Gerer, Fafan and middle Uebi Scebeli, up to the height of Bulo Burti in Italian Somalia (Jesomma sandstones). The predominantly calcareous facies, and frankly marine with Orbitoline and Rudiste, is distributed in strips in the upper Uabi, both in the Bale and in the Arussi and Cercer, then along the middle Uebi Scebeli and lower Fafan, between the Ogadēn Abdalla and Sciaveli area upstream of Barre, downstream of Bulo Burti to Missarole and Lammacad (series of Giglei) and finally in more or less extended strips in the coastal area of ​​the Gulf of Aden, both in British territory, as in the Italian territory and in the island of Socotra. The Eocene is represented by compact limestones in Alveolina, coarse limestones, compact limestones and richly fossiliferous nummulitic leafed marly limestones, sometimes flint (Carcar series, Boran series, Auradle and Allahkagid layers, Daban layers) with a complex interposed of sometimes selciferous marl, with gypsum and anhydrite (Taleh series, chalky-anhydrite formation). They almost entirely form the planking in the NE triangle. of the Cretaceous sandstone belt described above, to the NE. that is, of an Ergheisa-Mereg alignment. A strip of this Eocene limestone formation, with a cretaceous or granite base, also constitutes Socotra and the nearby islets. The Oligocene (Hafūn series) is represented by gypsum marls, sandstones and quartz sands and fossiliferous marly limestones, with Nummulites and Lepidocycline passing through marly limestone and coralligenic limestone, sometimes ceroid or crystalline, of the Miocene. These deposits form limited strips, distributed along the coasts both of the Indian Ocean, at N. di Obbia especially between the mouth of the Nogal and Cape Guardafui, and of the Gulf of Aden between Cape Guardafui and Bulhar. Pliocene marine deposits are not known: however, calcareous crustons and steppe limestones, travertines, aeolian sands, more or less lateritic red earths, sebca deposits, alluvial deposits belong to the Pliocene and the subsequent Quaternary etc. that veil the ground for large expanses a bit everywhere. Traces of a limited re-submersion and subsequent emergence are observed only on the edges of the peninsula, and are represented by coastal benches, now coral and shell-like, distributed along the entire coast of the Gulf of Aden and on that of the Indian Ocean from Capo Guardafui to Obbia; they are missing in the stretch between Obbia and the mouth of the Giuba, but are found here, near Giumbo and Chisimaio and in the coast and in the Bagiuni Islands (Oltregiuba). Volcanic rocks (especially basalts and liparitic or rhyolithic tuffs) of different tertiary and quaternary ages, extend in vast plagues of the elevated part of the plateaus, in the Lugh area, in the hinterland of Berbera, between Lasgore and Bender Ziade, in Bender Chor, etc..

Climate. – The climate of Somalia is, as a whole, an arid or semi-arid climate, very hot, and sub-desert in the northern and western part where the altitude also makes its influence effectively felt. The dominant motif is represented by the monsoons, periodic winds which in the summer blow from the southern maritime quadrants, and are therefore humid and somewhat less hot, in the winter instead they identify with the trade winds and blow from the NE., I.e. from elevated continental regions., and on which the thermal equator runs, so that winter is hotter and drier in most of the peninsula than summer. The rains fall in the two intermediate seasons, spring and autumn, and increase in quantity proceeding from the coast towards the interior, especially due to the altitude. So, while in Brava, in the maritime region, an average of about 300 mm is attributed. year, and in Afgoi, in the inner coastal zone, one of 421 mm., Harar, at the upper edge of the plateau, at m. 1856 on the sea, has 895 mm. rain. Even in the distribution of the rains during the year, uniformity is not observed: the distinction in two rainy periods that we have mentioned, and which is typical of the monsoon climate, is fully true in southern Somalia, for example in Mogadishu or Bardera; further north, towards the Harar, the two periods come together and merge into a single maximum of spring-summer rains, as on the Ethiopian plateau, depending on the Sudanese tropical regime, while towards the south, for example. at Chisimaio (384 mm), we pass to an equatorial regime. Harar the two periods come together and merge into a single maximum of spring-summer rains, as on the Ethiopian plateau, depending on the Sudanese tropical regime, while towards the south, for example. at Chisimaio (384 mm), we pass to an equatorial regime. Harar the two periods come together and merge into a single maximum of spring-summer rains, as on the Ethiopian plateau, depending on the Sudanese tropical regime, while towards the south, for example. at Chisimaio (384 mm), we pass to an equatorial regime. For Somalia travel information, please check zipcodesexplorer.com.

Somalia Geology