Presentation on theme: "What? Where? Why? How? Who?. What are we learning today? Waterfalls: How do differences in rock hardness affect them? What are the main features / parts."— Presentation transcript:
What are we learning today? Waterfalls: How do differences in rock hardness affect them? What are the main features / parts How do they change over time? How do people use them?
What causes waterfalls? Disclaimer: Riding in barrel over Niagara Falls not recommended!
Niagara Falls - Location Location The Niagara Falls are between Lake Erie and Lake Ontario, on the border between Canada and the USA. The falls are partly in Canada and partly in the USA and they are separated by Goat Island.
What is it Like? Views The river flows along transporting material before plunging down a 50 metre cliff! At the bottom of the cliff the water has worn away the softer rock to form a pool over 50 metres deep. This is called a plunge pool.
How was it formed? In this area, a band of hard limestone lies on top of softer shales and sandstone.
How has it changed over time? Over time the falls have created the Niagara Gorge. The falls are eating into the cliffs behind at nearly 1 metre a year! The gorge that is left behind is now 11 kilometres long.