1. by Earth or Tectonic Movements
a) Faulted or Rift Valley Lakes
i. During Rift Valley formation some parts of the rift valley floor sunk more than others.
ii. A long narrow and deep depression formed.
iii. Water from seepage and rain accumulated into these depressions to form lakes.
b) Down Warped and Tilted Lakes
Tensional and compression forces caused some parts of the earths crust to up warp while others down
warped.
i. A shallow depression formed.
ii. The depression may also be filled with water from rain or ground water.
iii. In the case of L. Victoria Rivers Kafu, Kagera and Katonga were tilted eastwards and Nyando, Yala and
Nzoia continued flowing west wards adding water into the depression.
- L.Victoria is the second largest fresh water lake after L.Superior.
- Has a maximum depth of 87m deep. Other examples of lakes are L. Kyoga and Wamala
c) Playas/sebkha is a lake contained in an inland drainage basin in a desert formed when rain or flood water
flows into a basin formed by crustal warping e.g. Chemchane Sebkha in Mauritania.
2. by Vulcanicity
i) Crater Lakes
- Lake formed by water accumulating into a crater.
- Are usually salty.
- A crater lake formed on an explosion crater is called maar.
- Examples are Lakes Mossoko in Tanzania, Paradise in Marsabit and Myungu in Uganda.
Crater lakes of Kelimutu (Image: Courtesy)
ii) Lava Dammed Lakes
- Formed as a result water accumulating on the upstream side of a lava barrier across a river.
i. Highly viscous lava erupts across a rivers course.
ii. It solidifies and blocks the river forming a lava dam.
iii.The rivers water accumulates behind the lava dam.
iv. A narrow and winding lake is formed e.g. Lakes Bunyonyi, Mutanda and Bulera in Uganda.
A lava dammed lake (Image: Courtesy)
3. by Erosion
a) Glacial Erosion
(i) Corrie/Tarn Lakes
Lake formed when water from melting snow accumulates into a corrie/cirque e.g. Teleki, Nanyuki and Hidden tarns on Mt. Kenya.
Tarn Lake formed from Glacial Erosion
(ii) Ribbon Lakes
- Finger like on a glaciated valley.
i. Glacier erodes the floor of a u-shaped valley.
ii. It over deepens some of its sections.
iii. Elongated hollow results.
iv. Water from melting ice accumulates into it forming a lake.
Ribbon Lakes (Image: Courtesy)
b) Wind Erosion
- Lakes formed when ground water accumulates in a depression formed by wind deflation and abrasion.
i. Wind continuously erodes the earths crust by deflation and abrasion.
ii. The water bearing rocks are reached.
Water oozes from the water table into the hollow or water from flash floods may accumulate in it to form
temporary lakes called pans e.g. in Quattara depression between Egypt and Libya and Etosha pan in
Namib.
c) Solution Lakes
Lakes formed when rain or ground water accumulates in depressions formed in limestone rocks when rain
water containing a weak carbonic acid dissolves limestone rocks e.g. Lakes Barber in Morrocco and
Ojikoto in Namibia.
4. by Deposition
a) River Deposition
- Formed when river deposition occur cutting off a section of a pronounced meander e.g. oxbow lakes
Shakababo and Mukunguya at lower part of Tana
b) Wave Deposition
- Lakes formed when wave deposition occurs across a rivers mouth or where the coastline changes suddenly
enclosing a body of calm water.
i. Waves break at an angle.
ii. The long shore drift causes materials to be progressively arranged across a rivers mouth resulting in a body
of calm water called a lagoon/sound.
Wave deposition
5. by Man
a) Dams are Lakes formed when water accumulates behind dams constructed across rivers resulting into a
large man made reservoir called man made lake e.g. behind Seven Forks Dam and Lakes Volta in Ghana and
Nasser in Egypt.
b) Barrage is a bank of earth or stones built across a river to provide water for farming.
