The geological setup around Lake Assal consists of volcanic basalt (3.4 – 1.0 Mya) formations. The nearest volcano to the lake, to its southeast, is the Ardoukôka, about away from the shores of the lake, which is marked on topographic map with (-) contour line. The southern part of the lake has sand patches whose width varies from about . There is hardly any arable land in the catchment. The important feature, from the point of view of the sources of water to the lake, is the Assal-Ghoubbet Rift, which is formed of recent basaltic formations (less than 1 Mya).