* Erosion: Erosion is the process of wearing away and transporting rock and soil. It's caused by factors like wind, water, ice, and gravity.
* Resistant Bedrock: Some types of bedrock are naturally more resistant to erosion. For example, granite is very hard and durable, while sandstone is softer and more easily eroded.
* Elevation and Time: Over millions of years, softer rocks erode at a faster rate, lowering the elevation of the land they form. The more resistant rocks, like granite, will be eroded more slowly, leaving them standing higher.
Here's an example:
Imagine a mountain range formed millions of years ago. It's made of both granite and sandstone. The sandstone, being softer, will erode faster than the granite. Over time, the sandstone will be worn away, leaving the granite peaks standing tall.
Important Note: While resistance to erosion is a key factor, there are other factors that can influence the elevation of rocks, including:
* Tectonic Uplift: Earthquakes and plate movements can uplift landmasses, raising the elevation of even the most eroded rocks.
* Glaciation: Glaciers can carve out valleys and erode rocks, sometimes leaving behind high peaks of resistant bedrock.
In summary, while other factors can play a role, the primary reason why the oldest rocks remain at the highest elevations is their inherent resistance to erosion.
