Geomorphology, Rivers & Glaciers Flashcards
Describe the different geological time scales.
- eons
- eras
- periods
- epochs
Describe how Earth has changed over time.
- Temperature of the climate has risen
- Continents have split apart
- Valleys have been formed by erosion
- Rivers and lakes have been formed by erosion and glaciers
Describe the key steps in the rock cycle.
- magma erupts from the volcano
- magma cools and forms solid (igneous) rock
- rock gets weathered and breaks down
- rock gets transported into rivers and seas
- rock gets weathered in the rivers (abrasion and attrition)
- rock breaks down into sediment
- sediment builds up on the seabed and compacts into layers and forms sedimentary rock
- sedimentary rock gets pushed down by pressure and heat and becomes metamorphic rock
- metamorphic rock gets crushed deeper into the ground and forms igneous rock
- magma erupts from the volcano
- etc…
What are the main characteristics of metamorphic rocks?
- formed when either igneous or sedimentary rocks change form
- heat and/or pressure will cause the elements in the original rock to react and re-form
- highly resistant to erosion and often used in building materials
What is weathering, erosion, transport, and deposition?
What are the key features and processes within a drainage basin?
How does a river change from its source to its mouth?
- gets wider
- in upper section of river, usually steep and narrow
- in middle section of river, usually sloping and wide
- in lower section of river, usually flat and very wide
How are river landforms (waterfalls, rapids, gorges, and V-shaped valleys) formed?
How do meanders and estuaries form?
What are the main causes of flooding (natural and human)?
How can places reduce the risk of flooding using hard engineering?
How can places reduce the risk of flooding using soft engineering?
Why have specific locations experienced severe flooding events?
What are the impacts of major flooding events?
What are glaciers?
A huge, slowly moving mass of ice that forms over many years. They very, very slowly erode paths through mountains, forming valleys.
How do glaciers form?
- snow falls in the same place
- gradually compacts, forming ice
- usually form above the snowline (above 3000 metres)
Where are glaciers currently located around the world?
- Greenland
- Antarctica
- Himalayas
- Arctic
- Alps
- Andes
- Rockies
- New Zealand
- Mt. Kilimanjaro
- Patagonia
- Iceland
Why does the global distribution of glaciers change over time?
Climate Change
- Ice melts faster
- Lack of snowfall
How do glaciers shape the landscape? Identify the key processes.
- plucking; rocks become frozen into the bottom and sides of the glacier. As the glacier moves downhill it ‘plucks’ the rocks frozen into the glacier from the ground
- abrasion; as the glacier moves downhill, rocks that have been frozen into the base and sides of the glacier scrape the rock beneath. The rocks scrape the bedrock like sandpaper, leaving scratches called striations behind
How does glacial ice create corries?
- snow gathers in mountain hollows (holes or depressions)
- as the ice moves downhill, it sticks to the back walk and plucks rock from the surface, steepening them
- freeze thaw action also loosens rocks on the back wall
- ice moving with loose rock acts like sandpaper and deepens the hollow by abrasion
- ice in a corrie has a rotational movement which means that the front of the corrie is less eroded and a lip forms
- the glacier melts, often leaving a tarn (also known as a corrie loch)
How does glacial ice create erratics?
- glacier plucks rock from the valley floor or sides
- glacier carries rock in its basal layer (bottom layer of the ice where material is trapped)
- after hundreds of kilometres, deposition or melting begins
- glacier loses energy and can no longer carry the rock
- glacier deposits rock in a new location
What eon are we currently in?
Phanerozoic
What era are we currently in?
Cenozoic
What are the main characteristics of igneous rocks?
- formed when magma solidifies
- as magma cools, mineral crystals begin to grow
- crystals will grow and form a hard crystalline rock
