Give two examples of geological changes that took place over millions of years. Are they physical or chemical? Explain.
Two examples of geological changes that took place over millions of years are the formation of mountains and the erosion of coastlines.
1. Formation of Mountains:
Over millions of years, tectonic forces acting on the Earth's crust can cause the uplift and formation of mountains. This process typically involves the movement of tectonic plates, resulting in the collision or subduction of one plate beneath another. As the plates collide, immense pressure builds up and causes the crust to buckle, fold, and push upward, forming mountain ranges. This geological change is primarily a result of physical processes, such as plate tectonics and the application of pressure.
2. Erosion of Coastlines:
Coastlines undergo constant changes due to erosion, which is the gradual wearing down of landforms by natural forces such as wind, water, and ice. For example, wave action, including the impact of waves and the movement of sediment, can erode coastal cliffs and reshaping shorelines over long periods. Similarly, rivers transporting sediment towards the coast can gradually carve out bays and estuaries. Erosion is primarily a physical process, where the force exerted by water, wind, or ice wears away rocks and transports sediments.
Both of these examples involve physical changes in the Earth's surface over millions of years. While there can be chemical reactions happening concurrently, such as weathering and mineral transformations, the overall geological changes in these cases are primarily driven by physical forces acting upon the Earth's crust.