Plate Tectonics - Chapter 1 Flashcards
Trench
Long, narrow deep depression in the ocean bed running parallel to a plate boundary and marking a subduction zone
Terrane
Fragment of crust broken off from one tectonic plate and stuck to another plate
Tectonic cycle
Continuous collision and separation of tectonic plates causing destruction and formation of earths crust
Subduction
Geological process at convergent boundaries here one plate sinks under another and is forced into mantle. Regions where occurs are called subduction zones
Eg. Nazca under South America
Sea floor spreading
Geological process at mid ocean ridges. Plates split apart causing formation of sea bed. Sea floor spreading is result of mantle convection
Rift Valley
A steep sided valley formed by downward movements of a block of the earths surface between nearly parallel faults
Eg. East African rift
Plate tectonics
Study of the processes that cause the movement of the earths crustal plates and resulting landforms
Plume
An up welling of unusually hot magma in the mantle. Form volcanic hotspots
Plates
Huge slabs of rock made of oceanic and continental lithosphere
Passive plate margin
The transition between oceanic and continental lithosphere. earthquakes and volcanic activity doesn’t occur here
Pangaea
The giant super continent containing all the landmasses on earth that existed 200-300 million years ago
Pacific Ring of Fire
Horse-shoe shaped zone around the edge of the Pacific. A lot of earthquake and volcanic eruptions. Lots of oceanic trenches, volcanic islands, arcs and volcanoes
Oceanic crust
Thin part of the earths crust which forms seabed. Made of basalt covered with ocean sediments.
Mid Ocean Ridge
Range of undersea volcanic mountains in the ocean. Forms when 2 tectonic plates separate. Associated with shallow earthquakes.
Lithosphere
Rigid outer layer of the earth. Includes crust and upper mantle
Laurasia
One of the 2 continents that formed after Pangaea around 200-300 million years ago. included North America, Europe and Asia
Island arc
Curved line of volcanic islands located at a destructive late margin with a deep ocean trench on convex sides. 2 oceanic plates collide
Hotspot
Place where magma pushes up through the crust in the middle of a tectonic plate to form a volcano. Form from plumes of magma rising from the mantle
Eg. Hawaii in the Pacific Plate
Gondwanaland
One of the continents formed after Pangaea around 200-300 million years ago. Included Antarctica, Australia, Saudi Arabia and Madagascar
Fold Mountains
Mountains formed by collision of 2 plates
Eg Alps or Himalayas
Fault lines
Cracks in crust along which movement happens. Fault lines can be big/ small
Eg. San Andreas Fault (Between Pacific and North American plate)
Exogenic
A force that occurs on the surface
Eg weather and erosion
Destructive / convergent plate boundaries
A region of earth where plates collide
Endogenic
A force the occurs on the inside, driven by heat from earths core
Eg. convection currents
Constructive / divergent plate boundaries
a region where new oceanic crust is formed when 2 plates separate
Eg. junction between Eurasia and North America
Continental drift
Slow movement of the continents across earths surface over millions of years
continental crust
The crust that forms the continents and the shallow area of seabed close to their shores
Conservation / transform plate boundaires
Junction between 2 plates that slide past each other without forming or destroying lithosphere
Eg. San Andreas Fault between Pacific and North American plate
Asthenosphere
Part of the mantle. Below lithosphere and made of partly melted rock. 180 km thick
