what can makes arches of rocks smooth and round?
O strong winds
O water freezing in the cracks
O earthquakes
O a river runnning through the ricks
All of the options you mentioned can contribute to the smoothing and rounding of arches of rocks. Here's a breakdown of how each factor affects the rocks:
1. Strong winds: Over time, continuous exposure to strong winds can erode and weather the rocks, causing them to become smoother and more rounded. The wind carries sediment particles that act as "sandblasting" agents, gradually wearing away the hard edges and rough surfaces of the rocks.
2. Water freezing in the cracks: When water enters cracks or joints in the rocks and freezes, it expands, exerting pressure on the surrounding rock. This cyclic freezing and thawing can gradually widen the cracks, leading to rock disintegration and eventually forming arches. The constant freezing and thawing process assists in smoothing and rounding the rock surfaces.
3. Earthquakes: Earthquakes can cause rocks to fracture and break along predetermined lines of weakness. Over time, this process can lead to the formation of arches as the broken sections of rock gradually separate and collapse, leaving behind an arched structure. However, earthquakes alone might not contribute significantly to smoothing the rocks, as erosive forces like wind and water play a more prominent role in that regard.
4. A river running through the rocks: When a river flows through a rocky area, the movement of water carries sediment particles that act as abrasives. As the rocks are continuously impacted by the flowing water and the sediment it carries, their surfaces become smoother and more rounded over time. This smoothness can contribute to the formation of arches as the softer parts of the rocks erode faster than the harder parts, leaving behind a curved structure.
It is important to note that these processes usually occur over long periods, sometimes thousands or millions of years, depending on the local environment and geological factors.