Well, if you mean layers of the earth than the 1st one would be crust the second would be the mantle and the third would be the outer core.
The answer would be The Berlin conference.
The combination of the weathering and erosion of the stream bank and the cutting into the bedrock from the velocity of the stream combine to make a "stream valley".
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What is stream valley?</h3>
A stream valley is an earthen dip where water is present at its lowest point. These valleys are the result of erosion, which is the transfer of decomposed rock or soil from one location to another.
The formation of stream valley is given below-
- The typically V-shaped stream valley is changed to a U-shaped valley because the U-shape offers the flowing glacier the least amount of frictional resistance.
- Because a glacier's cross section and viscosity are substantially greater than those of a river, its route has fewer and wider bends.
To know more about characteristics of weathering, here
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The answer is urban areas