Hydrosphere: Explain the Formation of a Waterfall Flashcards
What does the first diagram look like?
Rock that slopes slightly at the right. It has a darker layer on top (hard rock) with a lighter layer underneath (soft rock.) There is a river flowing along the surface.
What is the significance of the two different types of rock? ( ____ erosion)
Soft rock is less resistant, so it causes differential erosion as the soft rock will erode faster than the hard rock.
What process is explained in the first diagram next to the river? (definition too)
Hydraulic action is when the sheer force of the water enters cracks in the rock, compresses the air and forces pieces of rock to become dislodged.
What does the second diagram look like?
The hard rock sticks out whilst the soft rock has eroded, creating a waterfall with a plunge pool with rocks in the plunge pool.
The soft rock…
…undercuts the overhanging hard rock.
What do the rocks in the plunge pool cause? (process & definition)
The plunge pool is made deeper by abrasion which is when the force of the water throws bedload against the banks, causing erosion.
What happens to the hard rock?
The hard rock becomes unsupported and will eventually collapse into the plunge pool due to gravity
What does the third diagram look like?
Basically the same as the second, but there is no overhanging rock and the water flows straight down. and there is an arrow pointing left at the top
What is the ONE annotation of the third diagram
The waterfall retreats upstream.
