Describe the development of limestone topography. What is the name applied to such landscapes? From what area was this name derived?

Karst topography is a distinctive landscape that forms through the chemical weathering and erosion of soluble rocks, most commonly limestone, but also other rocks such as dolomite and gypsum. This unique landscape is characterized by a number of notable features, including disappearing streams, underground drainage systems, and a rough, irregular surface.

In regions with karst topography, rather than surface water running off into rivers and lakes, it often disappears into the ground, where it travels through a network of caves and voids. This underground water movement helps in the formation of caves, which is another hallmark of karst landscapes.

The weathering process in these areas is not uniform because it largely depends on the presence of cracks and fissures in the rock through which water can easily penetrate and dissolve the rock over time. The result of this, over many thousands of years, are features that make karst landscapes so spectacular and unique.

Dissolution of soluble rocks is a key process in the formation of karst landscapes. Soluble rocks, such as limestone, are composed largely of calcium carbonate, a compound that dissolves relatively easily in the weakly acidic waters that come from rain mixed with carbon dioxide from the atmosphere.

As rainwater seeps into cracks and crevices in the rock, it begins to dissolve the rock along these pathways. This enlarges the pathways and can create underground streams and caves. Furthermore, this process is influenced by factors such as the purity of the rock, the amount of rainfall, and the presence of vegetation. The purer the rock and the more rainfall, the faster the process will occur.

Limestone topography is a dynamic system, ever-changing with the continuous cycle of water dissolving rock and carrying it away, reshaping the landscape little by little. This dissolution is a slow but constant process that works over many thousands of years to sculpt the fascinating and intricate features of karst topography.

Cave formations, commonly known as speleothems, are another intriguing aspect of karst topography. These are mineral deposits that accumulate as water drips or flows through caves, leaving behind mineral traces that build up over time.

One of the most iconic cave formations is the stalactite, which hangs from the ceiling of a cave like an icicle. Stalactites form when water containing dissolved calcium carbonate drips from the ceiling and deposits a small ring of minerals with each drop. Correspondingly, stalagmites grow upwards from the cave floor, often created by water splashes as it hits the ground.

Other cave formations include flowstones, draperies, and helictites, each with unique shapes and patterns formed by water movement. These formations grow at varying rates, from less than a millimeter to several millimeters per year, and are sensitive indicators of the cave's environment. Their colors and sizes can tell a lot about the mineral content and historical conditions within the cave.

Sinkholes are dramatic features commonly associated with karst topography, formed by the collapse of surface layers into voids created by the dissolution of underlying soluble rocks.

These features can range from small, soil-lined bowls to large, deep depressions that can engulf entire buildings or streets. Sinkholes can form gradually, but often they appear suddenly, representing a serious geohazard in karst regions.

Sinkhole formation involves both the chemical dissolution of rock and mechanical processes. Over time, water erodes underground cavities in the rock. When the overlying sediments are no longer supported, due to the enlargement of these cavities, the ground collapses and a sinkhole is created.

The occurrence and development of sinkholes are influenced by several factors such as the type of rock below the ground surface, the level of the water table, and the presence of human activities like construction or water extraction. They are a potent reminder of the dynamic and often unpredictable nature of karst landscapes.