1. Describe how plants promote mechanical and chemical weathering but inhibit er
ID: 158 • Letter: 1
Question
1. Describe how plants promote mechanical and chemical weathering but inhibit erosion.
2. Mass wasting is influenced by many process associated with all four spheres of the Earth system. Select three items from the list below. For each, outline a series of events that relate the item to various spheres and to a mass-wasting process. Here is an example that assumes "frost wedging" is an item on the list: Frost wedging involves rock (geosphere) being broken when water (hydrosphere) freezes. Freeze-thaw cycles (atmosphere) promote frost wedging. When frost wedging loosens a rock on a cliff, the fragment tumbles to the base of the cliff. This event, called a rockfall, is an example of mass wasting. Now you give it a try. Use your imagination.
a. Wildfire
b. Spring thaw/melting snow
c. Highway road cut
d. Crashing waves
e. Cavern formation
Explanation / Answer
b. Spring thaw/melting snow
When debris is saturated with water (as from a heavy rain or melting snow), it becomes heavier and is more likely to flow downslope. Interestingly when a small amount of water in soil forms a thin film around each grain the surface tension of the water holds the grains together. It is surface tension which makes wet beach near the surf zone relatively hard and strong. In contrast, dry sand further up the beach has little strength because the surface film is gone. Likewise, when sand become saturated (water fills all the pore space), the surface tension no longer acts and the grains may be forced apart by the water. In this latter case, the grains can slide easily and, so, the sand or soil become very weak can easily slide down a slope.
c. Highway road cut
after making the road on hill ,if it rains heavily,soil absorbs water and becomes loose. when a very heavy vehicles move on the road soil looses its strength,then we have landslide
d. Crashing waves
at the shores when waves hit with high energy it disturbes the soil, makes it loose and takes away the soil along with it into the sea
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