Between the Upper Nile and the Eritrea border in Ethiopia is a region of elevated plateaus that are the home of various mountain ranges. These plateaus and mountains constitute the Ethiopian Highlands. The highlands are a clearly marked orographic division. The eastern wall of this plateau starts in Eritrea and runs parallel to the Red Sea from Ras Kasar to Annesley Bay. It then turns due south into Ethiopia.. There is a break in the wall, through which flows the Awash River. The main range at this point moves southwest, while south of the Awash Valley, below the level of the mountains, another massif rises in a direct line heading south. This second range sends a chain (the Amhar mountains) eastward toward the Gulf of Aden. The two chief eastern ranges maintain a parallel course south by west, with a broad upland valley in between that is full of lakes. The southern escarpment of the plateau is highly irregular. It overlooks Lake Turkana and the southern Debub Omo Zone. The western wall of the plateau is well marked and abrupt. On its northern face the plateau falls in terraces to the level of the eastern Sudan. The eastern escarpment is the best defined of these outer ranges. It has an average height of 2,100 to 2,400m, and in many places rises almost perpendicularly from the plain.

The physical aspect of the highlands is impressive. The northern portion consists of a huge mass of Archaean rocks with a mean height of 2,000 to 2,200 m above sea level, and is flooded in a deep central depression by Lake Tana. Above the plateau are several irregular mountain ranges which attain altitudes of from 3,700 to 4,600 m. Many of the mountains are of unusual shape. Characteristic of the country are the enormous fissures which divide it. They’ve been formed over time by water erosion. Some of the valleys are of considerable width; in other cases the opposite walls of the gorges are but two or three hundred meters apart, and fall almost vertically thousands of meters, representing an erosion of many hundred thousands cubic metres of hard rock. One result of the action of the water has been the formation of numerous isolated flat-topped hills or small plateaus with nearly perpendicular sides.. The Semien Mountains lie northeast of Lake Tana and culminate in the snow-covered peak of Ras Dejen, which has an altitude of 4,550 m. A few kilometers east and north of Ras Dejen are Mounts Biuat and Abba Yared. The Bale Mountains are separated from the larger part of the Ethiopian highlands by the Great Rift Valley, one of the longest and most profound chasms in Ethiopia.

Parallel with the eastern escarpment are the heights of Baila, Mount Abuna Yosef, and Kollo,. Between Lake Tana and the eastern hills are Mounts Guna, and Uara Sahia, Mount Choqa attains a height of 4,154 m. The southern portion of the highlands has more open tableland than the northern portion and fewer lofty peaks.