Mount Chilalo is an isolated, extinct silicic volcanic

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 mountain in southeastern Ethiopia

Ethiopia

Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

. The highest point in the Arsi Zone

Arsi Zone

Arsi is one of the 12 zones of the Oromia Region in Ethiopia. Arsi is also the name of a former province. Both the Zone and the former province are named after a subgroup of the Oromo, who inhabit both...

 of the Oromia Region

Oromia Region

Oromia is one of the nine ethnic divisions of Ethiopia...

, and located on the border between the Hitosa

Hitosa

Hitosa is one of the 180 woredas in the Oromia Region of Ethiopia. Part of the Arsi Zone, Hitosa is bordered on the south by Digeluna Tijo, on the southwest by Tiyo, on the west by Ziway Dugda, on the northwest by the Misraq Shewa Zone, on the northeast by Dodotana Sire, and on the east by Tena...

 and Tiyo

Tiyo (woreda)

Tiyo is one of the 180 woredas in the Oromia Region of Ethiopia. Part of the Arsi Zone, Tiyo is bordered on the south by Munesa, on the west by Ziway Dugda, on the northeast by Hitosa, and on the southeast by Digeluna Tijo. The administrative center of the woreda and Zone is Asella; other towns in...

 woreda

Woreda

Woreda is an administrative division of Ethiopia , equivalent to a district . Woredas are composed of a number of Kebele, or neighborhood associations, which are the smallest unit of local government in Ethiopia...

, this mountain has a latitude and longitude of 07°55′N 39°16′E with an elevation of 4036 metres (13,241 ft) above sea level.

The mountain has an elliptical base (about 30 by 20 kilometers), whose major axis lies NNE-SSW or parallel to the predominant tectonic trend. Chilalo rises with gentle slopes for more than 1500 meters from the top of the plateau. At the summit, there is a large, almost circular caldera

Caldera

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

 about 6 kilometers in diameter, whose southern rim is considered to be the mountain's summit. Mount Chilalo last erupted in the Pleistocene

Pleistocene

The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

.

One authority identifies Mount Chilalo as a late Trap Series volcano. The geologist Erik Nilsson claimed to have identified traces of glaciation on Chilalo, as well as on its neighbor Mount Kaka down to about 3400 meters, which he dated to the "Last Pluvial Period". Although this mountain is located south of the Great Rift Valley

Great Rift Valley

The Great Rift Valley is a name given in the late 19th century by British explorer John Walter Gregory to the continuous geographic trench, approximately in length, that runs from northern Syria in Southwest Asia to central Mozambique in South East Africa...

, along with Mount Gugu

Mount Gugu

Mount Gugu is a mountain located in central Ethiopia. Located in the Arsi Zone of the Oromia Region, this mountain has a latitude and longitude of , with an elevation of 3623 meters. It forms part of the divide between the drainage basins of the Awash and the Shebelle Rivers....

 to the north and Mount Kaka to the south, it is considered, geologically speaking, part of the Ethiopian Highlands

Ethiopian Highlands

The Ethiopian Highlands are a rugged mass of mountains in Ethiopia, Eritrea , and northern Somalia in the Horn of Africa...

.