Geography coasts and tectonics Flashcards
what is the Dalmatian coast?
Made up of offshore islands and coastal inlets running parallel to the coastline
What is a Haff coast?
Long sediment ridges topped by sand dunes that run parallel to the coast. You can see lagoons which are created between the ridge and the shore.
what are deformed strata
The degree to which rock units have been tilted or folded by tectonic activity
what is faulting?
The presence of major fractures that have moved rocks from their original positions
5 key points about tectonic hazard situation
- Concentrated along tectonic plate boundaries
- Ring of fire
- Types of hazard vary by the boundary
- Intraplate hazards
- Tsunamis
What is Tomography?
CAT scans of the lithosphere
What is the new theory of slab pull?
The plates are pulled down through gravitational sliding
What was the old theory of slab pull?
The heat generated from convection isn’t enough to pull the plates
What is ridge push
Newly formed oceanic crust at mid ocean ridges become denser and thicker as it cools. This causes it to sink under its own weight-pulling the rest of the plate down with it
what is a rift valley and what plate boundary is it formed at?
where plates move apart on continents the crust stretches and breaks to form faults formed at a divergant plate boundary
3 types of destructive/convergent boundary
1) when the oceanic plate sides beneath the continental plate because it is denser
2) when 2 oceanic plates meet and one subducts
3) when 2 continental plates meet and form high fold mountains
what forms at collision boundaries?
fold mountains
what can form at conservative plate boundaries?
faults
2 examples of intraplate earthquakes
Rhine Rift Valley
African Rift Valley
how are volcanic hotspots formed?
Magma upwells from the core and forms volcanic hotspots such as the yellowstone hotspot on the N. American plate
What is a mantle plume?
A stationary upwelling of abnormally hot rock within the Earth’s mantle
What is a hotspot
The place where the plume melts the mantle such as Hawaii
The Yellowstone Caldera chain
the current caldera is the most recent in a series of eruptions that span over millions of years.
The N. American plate is moving west over a stationary hotspot.
As the plate moves, the hotspot produces an enormous eruption every few million years.
This causes a chain of rhyolitic calderas
What is a caldera?
A large depression formed when a volcano erupts and collapses
what are 4 secondary impacts of an earthquake?
Tsunami’s
Fires
Aftershocks
Landslides
What is paleomagnetism?
the record of the strength and direction of the Earth’s magnetic field in rocks
What is sea floor spreading?
A geological process in which tectonic plates split apart and new ocean floor is created
what are the 4 different types of seismic wave?
S waves - can only travel through solids
Love waves - only travel through the solid parts of the earth’s surface
Rayleigh waves - surface waves that travel near the surface of solids.
P waves - can pass through the liquid outer core
What is subduction?
The sideways and downwards motion of the edge of a plate into the mantle beneath another plate. When enough mass has moved past the force arc it would begin to fall (gravity)
What is a locked fault?
a fault that is not slipping because frictional resistance on the fault us greater than the shear stress of the fault
who spotted that the plates used to fit together?
Abraham Ortelius
who spotted that there were 2 layers in the mantle?
Dan Mackenzie
Who spotted continental drift?
Alfred Wegener
properties of the Hawaiian eruptions?
Fluid lava flows from a volcano’s summit and radical fissures form shield volcanoes
properties of the Strombolian eruptions?
Moderate bursts of expanding gases that eject clots of incandescent lava in cyclical small eruptions
properties of Vulcanian eruptions?
Moderate explosions of gas laden with volcanic ash this mixture forms dark turbulent eruption clouds
properties of the Pelean eruption?
intensely violent
mount vesuvius in 29 AD
gas rich magma generates enormous and nearly continuous jetting blasts
properties of the Plinian eruptions?
Generate pyroclastic flow at a high velocity - extremely dangerous
properties of the icelandic eruptions?
effusions of basaltic lava
what makes magma more viscous?
Crystals make it more likely to explode then flow
What index is used to describe and compare the size or magnitude of volcanic eruptuons?
VEI (Volcanic Eruption Index)
uses a scale from 0 - not explosive to 8 - extremely
what are the several factors that the VEI uses to assign a number?
The amount and height of the volcanic material ejected
How long the eruption lasts
Qualitative description terms
