If a tree has grown out of the side of a rock cliff and a house was recently built on the land above causing the tree a lot more rain water to run off where the tree lives, it's roots have started to be exposed and are now growing faster and bigger with the increase of water. The rock eventually cracks and the tree falls down to the river.
Explain what is happening in this example using the words weathering or erosion and chemical, biological and or mechanical weathering.
In this example, we can observe the processes of weathering and erosion, as well as the roles played by chemical, biological, and mechanical weathering.
1. Weathering: Weathering refers to the breakdown or alteration of rocks and minerals at or near the Earth's surface. It can occur through various mechanisms.
2. Mechanical Weathering: Mechanical weathering involves the physical disintegration of rocks without any change in their chemical composition. One type of mechanical weathering is freeze-thaw weathering, where water seeps into cracks and then freezes, expanding and widening the cracks. The repeated cycles of freezing and thawing gradually weaken the rock.
In this example, the tree grows out of the side of a rock cliff. As the tree's roots grow, they exert mechanical pressure on the rock, causing it to weaken. This process is known as biological weathering since the tree is the contributing factor.
3. Chemical Weathering: Chemical weathering involves the transformation of rocks through chemical reactions. One common form is known as water weathering, where water combines with minerals in rocks, causing them to dissolve or react and undergo chemical changes. Another type is oxidation, where oxygen reacts with certain minerals, causing them to rust or change color.
In this example, the increase in rainfall from the newly built house on the land above the tree causes more water to run off onto the tree's roots. The excessive water carries dissolved minerals from the rock cliff, facilitating chemical weathering. Over time, the rock weakens due to the chemical reactions taking place and becomes more vulnerable to other forms of weathering.
4. Erosion: Erosion refers to the transportation of weathered rock materials by natural agents such as water, wind, ice, or gravity. It involves the removal, detachment, and transport of particles from their original location.
In this example, the combination of the weakening rock due to chemical and mechanical weathering, and the continuous force of water running off from the increased rainfall, leads to the eventual cracking of the rock. As the rock cracks, it becomes more susceptible to erosion by the river below. Eventually, the weakened rock gives way, causing the tree to fall down into the river.
In summary, the tree's growth on the side of a rock cliff leads to mechanical weathering, as its roots exert pressure and weaken the rock. The increased rainfall from the newly built house causes chemical weathering as it dissolves minerals from the rock. Ultimately, the weakened rock succumbs to erosion, leading to the tree's downfall.