Les Gours

Les Gours is a geographical term referring to a specific type of small lake or pond formed in calcareous (limestone) terrains, particularly those characterized by tufa deposits. These water bodies are typically shallow and often terraced or stepped due to the accumulation of calcium carbonate precipitated from the water. The term is primarily used in France, especially in regions with significant limestone formations such as the Jura Mountains and parts of the Massif Central.

Gours are created by the action of calcium-rich water flowing over obstacles (such as vegetation, small rocks, or even existing mineral deposits). As the water flows, carbon dioxide is released, which reduces the solubility of calcium carbonate. This results in the precipitation of calcium carbonate (CaCO3) in the form of tufa or travertine. Over time, this process builds up dams or barriers, creating a series of small pools or terraces, each holding a shallow body of water. The appearance is often a cascade of small, interconnected pools.

The water in gours is usually clear and highly alkaline due to the dissolved calcium carbonate. The specific flora and fauna adapted to these unique conditions often characterize them. Algae and certain types of aquatic plants thrive in these environments and contribute to the ongoing process of tufa deposition. They also provide a habitat for various invertebrates and sometimes small fish.

The formation of gours is a delicate process easily disrupted by human activity. Pollution, changes in water flow, deforestation, and quarrying can all negatively impact the formation and stability of gours. Protecting these unique ecosystems is crucial for maintaining biodiversity and preserving natural heritage. Gours are often features of protected areas and geological sites.