Which formation results from erosion processes acting on limestone?

The formation of caves and arches is directly linked to the erosion processes that act on limestone. Limestone is a sedimentary rock that is primarily composed of calcium carbonate. When rainwater, which is slightly acidic due to dissolved carbon dioxide, seeps through the soil and comes into contact with limestone, it begins to dissolve the rock in a process known as chemical weathering.

Over time, continuous erosion can create features such as caves, where the rock has been hollowed out, and arches, where the surrounding material has been eroded away, leaving a natural bridge-like structure. These formations are significant in karst landscapes, where limestone is prevalent. The development of caves and arches typically occurs in environments where there is a sufficient amount of rainfall to promote this ongoing erosive process.

In contrast, the other formations mentioned do not result from erosion of limestone. For instance, plate tectonics involves the movement of the Earth's plates and does not relate specifically to limestone erosion. Moraine refers to landforms composed of debris deposited by glaciers, which is unrelated to limestone. Shield volcanoes are geological formations resulting from volcanic activity and the eruption of fluid lava, also not connected to limestone erosion.