ⓘ Amba Aradam Formation. The Amba Aradam Formation is a Cretaceous sandstone formation in Ethiopia. It is up to 200 metres thick, for instance in the Degua Tembie ..

                                     

ⓘ Amba Aradam Formation

The Amba Aradam Formation is a Cretaceous sandstone formation in Ethiopia. It is up to 200 metres thick, for instance in the Degua Tembien district. As fossils are absent, the age of the Amba Aradam Formation was interpreted based on the age of assumed corresponding sandstones elsewhere in Ethiopia: the Debre Libanos Sandstones in the Blue Nile Basin, and the Upper Sandstone near Harrar in southeast Ethiopia, both of Late Cretaceous age. The lithology of the Amba Aradam Formation makes it less suitable for rock church excavation; caves have however been blasted in this formation to serve as headquarters for the TPLF during the Ethiopian Civil War of the 1980s.

                                     

1. Name and definition

The name" Amba Aradam Sandstone” was coined by geologist William Thomas Blanford, who accompanied the British invading army in 1868. The formation is named after the Amba Aradam mountain, where the formation widely outcrops. So far the nomenclature was not proposed for recognition to the International Commission on Stratigraphy.

                                     

2. Stratigraphic context

The Amba Aradam Formation overlies the Agula Shale at Imba Aradom and in the eastern part of Dogu’a Tembien; further to the west, it rests on the Antalo Limestone and then on the Adigrat Sandstone. After the deposition of the sands that were to become the Amba Aradam Formation, planation has occurred. This was then followed by the deposition of the Tertiary Trap Volcanics.

                                     

3. Lithology

The Amba Aradam Formation comprises white or red cross-bedded sandstones, and also mottled purple to violet siltstones and claystones. The sandstones are composed of quartz grains, cemented by clay minerals and iron oxides. The sediment was probably deposited in rivers. The iron oxide cementation laterisation makes the upper part of the formation harder, heavier and almost impervious for water. Locally, conglomerates occur.

                                     

4. Geographical extent

Besides at Imba Aradom, the formation outcrops on the ridges north of Imba Alaje, and particularly in the Dogua Tembien district, all in the Tigray region of Ethiopia.

                                     

5. Current geomorphology of the Amba Aradam Formation

The mesas of the Amba Aradam Formation, locally with trap volcanic cover, have an alternance of steep slopes and short moderate sections due to the alternance of beds of sandstone and layers of less resistant claystone or siltstone. The formation does not have high vertical cliffs like the Adigrat Sandstone. The iron-cemented upper part of the formation forms however steep cliffs, which can be more than 10 metres 33 ft high. These layers are also impermeable, what results in a spring line at the edge of the Amba Aradam sandstone cliff.

                                     

6. Caves used as headquarters during the Ethiopian Civil War

In the 1980s, during the civil war, the Tigray People’s Liberation Front TPLF excavated a cave in the sandstones of the Amba Aradam Formation, using dynamite. The cave is located near the Addi Gezaiti village, to the west of Hagere Selam, and served as offices for its leaders, including Meles Zenawi and Siye Abraha. The allied Ethiopian People’s Democratic Movement EPDM installed its HQ in a nearby cave at Melfa. Major military operations were coordinated from these caves almost until their victory against the Derg government in 1991. Both caves can be visited on appointment.



                                     
  • Amba Aradam is a table mountain in northern Ethiopia. Located in the Debub Misraqawi Southeastern Zone of the Tigray Region, between Mek ele and Addis
  • The formation covers Mesozoic sedimentary rocks, particularly Amba Aradam Formation and Adigrat Sandstone. In many places, on its upper side, deposits
  • Fossilworks.org Usno Formation at Fossilworks.org Fejej Formation at Fossilworks.org Amba Aradam Formation at Fossilworks.org Mugher Mudstone at Fossilworks
  • submarine Aradam was an Adua - class submarine built in the 1930s, serving in the Regia Marina during World War II. She was named after the Amba Aradam mountain
  • catchment is Agula Shale, Mekelle Dolerite, and sandstone of the Amba Aradam Formation Part of the water that could be used for irrigation is lost through
  • catchment is Mekelle Dolerite, Agula Shale, and, at the upper edge, the Amba Aradam Formation Part of the water that could be used for irrigation is lost through
  • shale, marls and evaporites Adigrat Sandstone, Antalo Limestone, Amba Aradam Formation A third major plantion surface and unformity formed in the following
  • the reservoir is Antalo Limestone, Agula Shale, sandstone of the Amba Aradam Formation and Ashangi Basalts. The main driving factors that define the variability
  • higher to the lower locations, the following geological formations are present: Amba Aradam Formation Agula Shale Mekelle Dolerite Antalo Limestone Quaternary
  • the following geological formations are present: Upper basalt Interbedded lacustrine deposits Lower basalt Amba Aradam Formation Adigrat Sandstone The main
  • the lower locations, the following geological formations are present: Lower basalt Amba Aradam Formation Adigrat Sandstone As there are no permanent rivers