Final answer:
Cliffs are formed through erosion, caves are formed through erosion of limestone, arches are formed through erosion and weathering, and stacks are formed through coastal erosion.
Step-by-step explanation:
Erosional landforms are created through various processes, primarily erosion. Cliffs are actually a result of erosion, not deposition. Over time, the continuous action of waves, wind, or water erodes the base of a cliff, causing it to collapse and retreat. Caves, on the other hand, are formed by the erosion of limestone rocks. Limestone is a type of sedimentary rock that dissolves easily in water, so when water flows through cracks in the limestone, it gradually enlarges those cracks, creating caves.
Arches, like the natural arches found in places like Utah's Arches National Park, are not created by tectonic plate movements. Instead, they are formed through a combination of erosion and weathering. Over time, wind and water erode the rock around a harder layer, leaving behind an arch-shaped structure.
Stacks, or sea stacks, are actually formed by coastal erosion. When waves erode a cliff, they form a sea stack when one portion of the cliff is gradually eroded more quickly than the rest, leaving behind a pillar-like structure in the water.