Emi Koussi

Emi Koussi is a giant volcano.

It is the highest mountain in the Sahara desert. It sits in a land called Chad.

The top of the mountain has two big holes. One hole looks like a giant, deep pit.

This pit has a white floor made of salt. The mountain is so big that astronauts can see it from space. It is a very special place to study.

Emi Koussi is a very big volcano.

It is in the Tibesti Mountains in Chad. It is the highest mountain in the Sahara desert. It reaches 3,447 metres in height.

This is a shield volcano. A shield volcano has a wide shape like a warrior's shield.

The top of the volcano has two large holes. We call these holes calderas. They are large pits made when a volcano erupts.

One big caldera is 15 by 11 kilometres wide. Inside it sits a smaller hole called Era Kohor. This smaller hole is 350 metres deep. Its floor is white from salt deposits.

Scientists study this place to learn about space. It looks like a volcano on Mars called Elysium Mons. The volcano was active long ago. Today, it still has hot springs. These are places where warm water comes from the ground.

Astronauts can even see this landmark from space.

Emi Koussi is a huge volcano in the Sahara desert.

It sits in the Tibesti Mountains in northern Chad. This mountain is the highest peak in the entire Sahara. It reaches an elevation of 3,447 metres.

The volcano is a shield volcano. This means it has a wide, sloping shape. It is about 60 to 70 kilometres wide. The total volume of the volcano is 2,500 cubic kilometres.

Some astronauts think it is a very easy landmark to see from space.

Two large pits sit at the top of the volcano. Scientists call these pits calderas.

The first caldera is about 15 by 11 kilometres wide. A second, smaller caldera sits inside the first one. This smaller pit is named Era Kohor. It is 2 kilometres wide and 350 metres deep.

The floor of Era Kohor is deep white. This is because of sodium carbonate deposits. There is also a salt lake on the floor. Many lava domes and cinder cones sit along the sides too.

This volcano was built in stages over a long time. The oldest part of Emi Koussi is about 2.4 million years old. During the first stage, it erupted rocks called trachytes. The second stage created lava domes and flows. The third stage involved phonolitic eruptions.

These stages each helped form the large calderas we see today. Some eruptions were very explosive. These explosions left large blocks of rock inside the summit. The volcano was very active during the Pliocene and Quaternary periods.

Geologists study the rocks to understand how the Earth works. The Tibesti Mountains grew on top of a large dome. Some scientists think a mantle plume helped make these volcanoes. Others think the collision of Africa and Europe played a part.

The volcano has erupted many different types of rock. These include rocks like basalt, phonolite, and trachyte. These rocks contain minerals like olivine and magnetite. Even Neolithic societies used these volcanic rocks as raw materials. The area is hard to study because it is so remote.

Emi Koussi helps us learn about other worlds. It is an analogue for a volcano on Mars.

That Martian volcano is called Elysium Mons. Scientists compare the two to understand how Mars might work. The mountain also has a unique climate. It is a desert mountain climate with very little rain.

Even though it is a desert, you can find plants there. Some plants, like the wood rush Luzula tibestica, only grow on Emi Koussi. You can also find hot springs that stay at 37 degrees Celsius.

Emi Koussi is a massive high pyroclastic shield volcano.

It is located at the southeast end of the Tibesti Mountains. This mountain range sits in the central Sahara within northern Chad. Emi Koussi is the highest mountain in the entire Sahara Desert. It reaches a peak elevation of 3,447 metres.

The volcano is very wide, measuring between 60 and 70 kilometres across. Its total volume is estimated at 2,500 cubic kilometres. Because of its size and shape, some astronauts consider it a very recognizable landmark from orbit.

The structure of the volcano is defined by its unique shape and nested pits. It is a shield volcano, which means it has broad, sloping sides. The summit features two overlapping calderas, which are large pits formed by volcanic activity.

The outer caldera is an elliptical shape about 15 by 11 kilometres wide. This outer ring was formed in stages, with a northern caldera forming before a southern one. The southern caldera is about 50 metres deeper than the northern one. Nested inside this large area is a smaller caldera called Era Kohor.

Era Kohor is 2 kilometres wide and 350 metres deep. It looks like a giant hole and is also known as the Natron Hole. Its floor sits at 2,670 metres and is covered in white sodium carbonate deposits and a salt lake.

Geologists believe the volcano was built through three distinct eruptive stages. The first stage occurred between 2.42 and 2.33 million years ago. During this time, the volcano erupted trachytes and trachyandesites as ignimbrites and basaltic lapilli. The second stage involved trachytic and phonolitic lava domes along with basaltic lava flows. The third stage was dominated by phonolitic eruptions, including the Kohor ignimbrite. Each of these stages was accompanied by the formation of a caldera. Recent volcanic activity includes the creation of maars, which are low-relief volcanic craters. Long lava flows and several scoria cones also sit on the slopes.

The history of the Tibesti Mountains involves complex tectonic movements. Scientists suggest that a mantle plume, which is a rising column of hot rock, helped form these volcanoes. Another theory suggests that the collision between Africa and Europe caused tectonic effects that created the range. The oldest rocks beneath the mountains are Precambrian granites and schists. The volcanic rocks themselves rest on an uplifted basement of sandstone. Emi Koussi has erupted many specific types of rock, such as phonolite and basalt. These rocks contain various minerals, including olivine, magnetite, and alkali feldspar. Even ancient Neolithic societies used these volcanic rocks as raw materials.

Climate and biology on Emi Koussi are shaped by its high elevation. The mountain has a desert mountain climate with very little rain. Annual precipitation is estimated to be only between 80 and 120 millimetres. However, the environment was different during the Holocene period. About 5,400 years ago, the Era Kohor caldera held a large lake. This lake was 130 metres deep and covered 4.1 square kilometres.

Today, the area is much drier, but the lake left behind diatom beds in the sediment. These are remains of tiny, single-celled algae that lived in the water.

Despite the harsh desert conditions, different types of life exist on the mountain. Vegetation is organized into five different belts based on how high they grow. At lower elevations, you can find the plant Erica arborea. The summit region contains Artemisia-Ephedra steppes. On the high lava flows, you can find ferns, mosses, and liverworts. Some plants are very rare and are only found here. For example, the wood rush Luzula tibestica is endemic, meaning it grows only on Emi Koussi. You can also find active fumaroles, which are openings that release volcanic gases. Near these vents, hot springs produce water that stays at 37 degrees Celsius.

Emi Koussi is highly significant for modern space science. Scientists use the volcano as an analogue to study other planets. An analogue is a place on Earth that looks and acts like a place in space. Specifically, Emi Koussi is compared to Elysium Mons, a volcano on Mars. By studying how eruptions and minerals work here, researchers can better understand Martian geology. This connection makes the remote mountains of Chad a very important site for understanding the solar system.