The Ashangi Basalts are the earliest Tertiary volcanic rocks in north Ethiopia, hence they are in the lowest position.

[1][2][3] The name was coined by geologist William Thomas Blanford, who accompanied the British Expedition to Abyssinia in 1868,[4] after Lake Hashenge in Tigray, which is surrounded by large outcrops of the formation.

The lower succession, the one that overlies the Amba Aradam Formation and the Adigrat Sandstone holds vertical and closely spaced columnar joints.

A common characteristic of the columnar joints observed in the Ashangi Basalts is their pentagonal or hexagonal shape (in plan view).

[2] The Ashangi formation occurs widely in Tigray Region, including the May Ch'ew area and Dogu’a Tembien.