By: Elizabeth Ann McNulty 

Millions of lakes can be found around the world! Lakes are bodies of water surrounded by land, and they vary greatly in size, depth, location, and origin, and there is a story behind how each lake forms. Additionally, lakes also play a key role in ecosystems, providing us with water, food, plants, and sustaining diverse species that depend on these lakes for their survival. They are mainly affected by temperature, wind, and light, which all vary based on the location of the lake. Since lakes form in many different ways, such as through glacier activity, tectonic movement, volcanic activity, river systems, and human engineering, understanding these processes is essential for recognizing the important roles lakes have in maintaining a healthy environment (Lake, 2023). 

 

Glacial Lakes:    Above is an image of a glacial lake (Aerial, 2017). 

Glaciers are massive bodies of snow and ice that have accumulated over thousands of years and move slowly across land. During the last Ice Age, many lakes formed when these glaciers moved across the land, carving out deep basins.  When the climate started to warm up around 10,000-15,000 years ago, the glaciers began to melt, and the water from the glaciers dripped and flowed down to fill these spaces, creating lakes. This process is one of the most common processes of lake formation, and it mainly occurred in regions such as Europe and North America (Knibb, 2023). 

 

Tectonic Movement :  Above is an image of a tectonic lake, called the Caspian Sea, which is the world’s largest lake, located between Asia and Europe. (Schmalz, 2010) 

Seven major tectonic plates make up the crust of the Earth and have been moving throughout history. This movement causes volcanic eruptions, earthquakes, formation of mountains, but it can also lead to the creation of lakes. Tectonic lakes are created as a result of the deformation of the Earth’s crust. When the crust fractures or folds along the fault lines, basins or depressions are developed, which gradually fill with precipitation, groundwater, or inflowing streams to become lakes. They are essential because they act as water storage, provide unique habitats for species, as well as recreation (Tectonic, n.d.). 

Volcanic Activity : Above is Crater Lake located in the caldera of Mount Mazama, Oregon. It is one of the deepest and clearest lakes in the world.  

Some lakes form when the crater (also known as the caldera) of inactive volcanoes fill up with rain or snow once a volcano becomes inactive, creating what are known as crater lakes. Volcanic lakes are produced by volcanic activity and are often referred to as volcanogenic lakes because they originate from volcanoes, with crater lakes being the most common type. Lava lakes are rare, and temporary types of lakes found in active volcanoes occur when molten lava collects in a depression and partially fills it (Volcanic, n.d.). 

Fluvial Lakes: Above is an image that shows a fluvial lake in the Great Lakes Coastal Wetlands (An example, 2021), 

Fluvial lakes are bodies of water formed by the movement of running water from rivers changing their course and developing into unique basins. These lakes are shaped by geomorphological processes such as erosion, channel migration, and deposition. When the rivers shift, they leave behind cutoffs or depressions that create fluvial lakes. They are open lakes, meaning that they connect to rivers, and differ from closed lakes: lakes that do not connect to any rivers. They have a key component in floodplain ecosystems, where they act as natural storage areas and provide habitats for fish, and other wildlife, supporting biodiversity. Fluvial lakes contribute to resources we use in daily life, such as improving water quality and running nutrient dynamics (Fiveable, 2024). 

 

Artificial Lakes: Above is an image of Lake Kariba in Central Africa, which is the largest man-made lake in the world (The Editors, 2025). 

In addition to all these lakes formed by natural processes, humans create lakes for purposes such as water storage, flood control, wildlife habitat, and hydroelectric power. Engineers carefully plan the shape, location and design of the lakes to make sure it is sustainable and beneficial to the surrounding environment. First, experts decide which depression, basin, or valley to use by conducting geographic surveys and environmental studies. Builders then construct a dam from materials like concrete, rock, or earth to block the natural flow from running water of rivers. The reservoir fills with precipitation, river inflow, and groundwater, and water management systems are installed to help regulate the levels of the water in the lake and aid in producing electricity. These new lakes transform ecosystems by supporting habitats for fish, birds, and plants, as well as helps provide us with clean water, power, recreation and drinking water. (How are, n.d.) 

From natural processes like the movement of glaciers, tectonic plates, or rivers, to human-made reservoirs, every type of lake helps contribute to biodiversity and maintains a healthy ecosystem by regulating water systems and providing unique habitats for wildlife.  

Bibliography:

Aerial view of body of water : lake in the mountains [Photograph]. (2017, August 22). Unsplash. https://www.sciencealert.com/study-says-glacier-lakes-are-accelerating-disappearance-of-permanent-ice

An example of a riverine Great Lakes coastal wetland [Photograph]. (2021, January 19). United States Environmental Protection Agency. https://19january2021snapshot.epa.gov/great-lakes-monitoring/summary-great-lakes-coastal-wetland-monitoring-program-cwmp_.html   

Fiveable. (2024, August 20). 1.3 Fluvial lake formation – Limnology. https://library.fiveable.me/limnology/unit-1/fluvial-lake-formation/study-guide/1NC17gh2C0HPgTbw   

Gautier, A. (2022, February 15). What are glacial lakes? National Snow and Ice Data Center. Retrieved September 3, 2025, from https://nsidc.org/learn/ask-scientist/what-are-glacial-lakes   

How are man made lakes made. (n.d.). Western Liner. Retrieved September 7, 2025, from https://westernliner.com/blog/how-are-man-made-lakes-made/   

Knibb, F. (2023, September 27). How are lakes made? Deep Sea World. Retrieved September 3, 2025, from https://www.deepseaworld.com/water/how-are-lakes-made/   

Lake. (2023, October 19). National Geographic. Retrieved September 1, 2025, from https://education.nationalgeographic.org/resource/lake/  

Schmaltz, J. (2010, June 4). NASA Caspian Sea [Photograph]. https://earthobservatory.nasa.gov/images/44253/caspian-sea  

Tectonic lakes. (n.d.). Prepp. Retrieved September 6, 2025, from https://prepp.in/news/e-492-tectonic-lakes-types-of-lakes-geography-notes  

The Editors of Encyclopaedia Britannica (2025, January 31). Lake Kariba. Encyclopedia Britannica. https://www.britannica.com/place/Lake-Kariba  

Volcanic lakes. (n.d.). Prepp. Retrieved September 6, 2025, from https://prepp.in/news/e-492-volcanic-lakes-types-of-lakes-geography-notes