Isalo

Isalo National Park is a National Park in the Ihorombe Region of Madagascar. The park is known for its wide variety of terrain, including sandstone formations, deep canyons, palm-lined oases, and grassland. The closest town is Ranohira, and the closest cities are Toliara and Ihosy. A local guide is required for visitors entering the park, and guides and porters can be hired in Ranohira. Treks in the park can last from several hours to a week or longer.

The main threat to this park comes from illegal wildfires set in the park. The wildfires limit the extent of forest and maximize grasslands used by cattle.

Erosion is the process by which soil and rock are removed from the Earth's surface by exogenetic processes such as wind or water flow, and then transported and deposited in other locations.

While erosion is a natural process, human activities have increased by 10-40 times the rate at which erosion is occurring globally. Excessive erosion causes problems such as desertification, decreases in agricultural productivity due to land degradation, sedimentation of waterways, and ecological collapse due to loss of the nutrient rich upper soil layers. Water and wind erosion are now the two primary causes of land degradation; combined, they are responsible for 84% of degraded acreage, making excessive erosion one of the most significant global environmental problems.

Industrial agriculture, deforestation, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion. However, there are many available alternative land use practices that can curtail or limit erosion, such as terrace-building, no-till agriculture, and revegetation of denuded soils.

Karst topography is produced by the dissolution of bedrock by water. It frequently involves caves.^{[citation needed]}