- Created by: AmyAnd99
- Created on: 04-03-20 20:18
SAND SILT MUD
High energy ------------------> Low energy
river-dominated deltas are branch shaped (birdsfoot?) eg. Mississippi
wave-dominated deltas are more fan-shaped eg. Nile
tide-dominated deltas have bays of sediment eg Ganges or Maracaibo
Processes remain the same
'PROGRADATION' is the movement of sediment into the delta
the energy levels are higher at the beginning of the delta (the delta plain), and lower nearer the sea (the prodelta).
Chemical Sediments- Reefs
Limestone Case Study-Reefs
Modern reefs are mainly equatorial
1. A volcano rises from the ocean floor
2. The volcano eventually becomes extinct and begins to erode. A fringing reef forms at the base of the volcano
3. The volcanic island subsides as the reef builds up, forming a lagoon in the middle of the reef. There may still be a remnant of the island above sea level.
4. With continued subsidence, the reef completely covers the buried island.
Volcanoes and Earthquakes
Why do they occur?
-Movement at plate boundaries and plate margins
-Quakes: rock builds pressure, becomes elastic, breaks and releases energy
-Volcanoes: hot magma rises in the rocks and makes its way to the surface where it erupts or oozes out
How do we predict?
-History: has it happened before?
-Strange topography: is there landscape evidence (offset rivers, ridges, tilted trees, etc)?
-Seismometers, global positioning systems
Volcanoes and Earthquakes Pt 2
How do we cope?
-Building standards and regulations, not developing in high-risk areas, etc.
-Earthquake safety programs and education.
What are the benefits?
-Volcanoes: fertile ground, microclimate, associated tourism (eg, Hawaii), geothermal energy
-Quakes: seismic networks are useful for managing quakes, landslides and explosions.
Climate Change- Greenhouse Gas
4.6 billion years ago the Sun's output was only 70% of the present.
With today's atmosphere, this would mean that the earth would've been around -25oC.
Yet there is proof that there was liquid water on earth.
How could this be? There must have been a lot of greenhouse gases in the atmosphere keeping the earth warm.