lithosphere/Geosphere Flashcards
How old is planet Earth?
Approximately 4.54 billion years old
The Earth is made up of 4 main layers:
crust
mantle
outer core
inner core
what is the crust?
we live on the crust
the crust is made up of two parts: the Continental Crust and the Oceanic Crust.
Continental Crust:
thick (10-70km)
- buoyant (less dense than oceanic crust)
- mostly old
Oceanic Crust:
- thin (~7 km)
- dense (sinks under continental crust)
- young
parts of the lithosphere/Geo?
sand, lava, rocks are all part of the lithosphere/geo.
earths crust:
The Earth’s crust is divided into 12 major plates which move in various directions.
This plate motion causes them to collide, pull apart, or scrape against each other.
Each type of interaction causes a characteristic set of Earth structures or “tectonic” features.
The word, tectonic, refers to the deformation of the crust because of plate interaction.
What are tectonic plates made of?
Plates are made of rigid lithosphere.
The lithosphere is made up of the crust and the upper part of the mantle.
What lies beneath the tectonic plates?
Below the lithosphere (which makes up the tectonic plates) is the asthenosphere
How are plates moved?
Plates of lithosphere are moved around by convection currents in the semi fluid asthenosphere in the upper mantle
Divergent Boundaries
= Spreading ridges, As plates move apart new material is erupted to fill the gap.
iceland has a divergent plat boundary
Convergent Boundaries
There are three styles of convergent plate boundaries
Continent-continent collision
Continent-oceanic crust collision
Ocean-ocean collision
Continent-Continent Collision =
Forms mountains, e.g. European Alps, Himalayas
Continent-Oceanic Crust Collision
this is Called SUBDUCTION
Subduction:
Oceanic lithosphere subducts underneath the continental lithosphere
Oceanic lithosphere heats and dehydrates as it subsides
The melt rises forming volcanism
E.g. The Andes
Ocean-Ocean Plate Collision:
When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone.
The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench.
The worlds deepest parts of the ocean are found along trenches.
E.g. The Mariana Trench
Transform Boundaries
Where plates slide past each other
At transform boundaries lithosphere is neither created nor destroyed.
Volcanoes are formed by?
Subduction - Rifting - Hotspots
What are Hotspot Volcanoes?
Hot mantle plumes breaching the surface in the middle of a tectonic plate
Earthquakes and Plate Tectonics…
As with volcanoes, earthquakes are not randomly distributed over the globe
At the boundaries between plates, friction causes them to stick together. When built up energy causes them to break, earthquakes occur.
