<P> Downcutting , also called erosional downcutting , downward erosion or vertical erosion is a geological process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream 's bed or the valley 's floor . The speed of downcutting depends on the stream 's base level , the lowest point to which the stream can erode . Sea level is the ultimate base level , but many streams have a higher `` temporary '' base level because they empty into another body of water that is above sea level or encounter bedrock that resists erosion . A concurrent process called lateral erosion refers to the widening of a stream channel or valley . When a stream is high above its base level , downcutting will take place faster than lateral erosion ; but as the level of the stream approaches its base level , the rate of lateral erosion increases . This is why streams in mountainous areas tend to be narrow and swift , forming V - shaped valleys , while streams in lowland areas tend to be wide and slow - moving , with valleys that are correspondingly wide and flat - bottomed . The term gradient refers to the elevation of a stream relative to its base level . The steeper the gradient , the faster the stream flows . Sometimes geological uplift will increase the gradient of a stream even while the stream downcuts toward its base level , a process called `` rejuvenation . '' This happened in the case of the Colorado River in the western United States , resulting in the process that created the Grand Canyon . </P>
<P> Downcutting , also called erosional downcutting , downward erosion or vertical erosion is a geological process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream 's bed or the valley 's floor . The speed of downcutting depends on the stream 's base level , the lowest point to which the stream can erode . Sea level is the ultimate base level , but many streams have a higher `` temporary '' base level because they empty into another body of water that is above sea level or encounter bedrock that resists erosion . A concurrent process called lateral erosion refers to the widening of a stream channel or valley . When a stream is high above its base level , downcutting will take place faster than lateral erosion ; but as the level of the stream approaches its base level , the rate of lateral erosion increases . This is why streams in mountainous areas tend to be narrow and swift , forming V - shaped valleys , while streams in lowland areas tend to be wide and slow - moving , with valleys that are correspondingly wide and flat - bottomed . The term gradient refers to the elevation of a stream relative to its base level . The steeper the gradient , the faster the stream flows . Sometimes geological uplift will increase the gradient of a stream even while the stream downcuts toward its base level , a process called `` rejuvenation . '' This happened in the case of the Colorado River in the western United States , resulting in the process that created the Grand Canyon . </P>
the lowest point a stream will erode is known as
the lowest point a stream will erode is known as
Downcutting
Downcutting