Plate boundaries and their landforms&features Flashcards
1
Q
Divergent plate boundary
A
- formed when 2 plates move apart from each other (tensional/pulling force)
- move apart, leave a gap, magma rise from mantle, form new lithosphere on surface
- constructive plate boundary (new land is formed)
2
Q
OP-OP Divergence (what landforms/features are found)
3 pts
A
- New Sea Floor
- Mid-Oceanic Ridge
- Submarine/Undersea volcanoes
3
Q
New Sea Floor (OP-OP- Divergence)
A
- plates move apart, tensional forces create fractures at plate boundary
- magma rises from mantle to fill gap
- magma cools and solidifies, forming new sea floors which extend the current ones
- process known as sea-floor spreading
4
Q
Mid-Oceanic Ridge (OP-OP Divergence)
A
- when more magma piles up and solidifies, form a chain of mountains on either sides of spreading zones
- plates continue to diverge, mountains move away from spreading zone, new ones formed
- rows and rows of mountains (rising 2000-4000m from ocean floor) called mid-oceanic ridge
- e.g. Mid-Atlantic Ridge
5
Q
Submarine/Undersea volcanoes
A
- when 2 plates diverge, gap is formed
- magma rises from mantle to fill gap
- piles around a vent in successive layers to form volcanoes (also known as undersea/submarine volcanoes)
- some of them rise above sea-level to form volcanic islands
- e.g. Surtsey (an island south of Iceland, lies along the Mid-Atlantic Ridge, very active)
6
Q
CP-CP Divergence (landforms/features found)
3 pts
A
- Rift valley
- New Sea
- Volcano (very rarely)
7
Q
Rift valley (CP-CP divergence)
A
- as CPs move apart, stretched, cause fractures to form at the boundary
- land in between CPs sink as a result of the divergent movement
- linear depression formed is called a rift valley
- e.g. East African Rift Valley
8
Q
New Sea (CP-CP divergence)
A
- overtime, the gap left behind at the divergent boundary between continent may be filled with water to form a water body e.g. sea
- formation of sea bed pushes landmasses apart
- spreading continue, sea grows wider
- e.g. Red Sea (formed due to divergence of African and Arabian Plate)
9
Q
Volcano (CP-CP divergence)
A
- CP move apart, stretched, fractures at boundary
- magma rises thru fractures from mantle, reach surface thru the vent
- on earth surface, magma known as lava
- hot and liquid lava piles around vent in successive layers to form a volcano
10
Q
Convergent Plate Boundary
A
- formed when two plates converge or collide
- at this boundary, the denser plate will sink/be forced under the the less dense one into the mantle
- process in called subduction and it takes place at the subduction zone
- as sinking crust moves into mantle, the crust melts under intense heat and pressure
- destructive boundary since crusts are being destroyed in the process
11
Q
Landforms/features found between OP-OP convergence
2 pts
A
- Oceanic Trench
2. Undersea Volcanoes and volcanic islands
12
Q
Oceanic trench (OP-OP convergence)
A
- when 2 OCs collide, the denser one is forced to sink under the less dense one at the subduction zone
- this forms a long deep depression in the ocean floor (oceanic trench)
- e.g. Mariana Trench (abt 11km deep)
13
Q
Undersea volcanoes and volcanic islands (OP-OP convergence)
A
- when two OCs collide or converge, the denser (and older) one will sink/ be forced under the less denser one and into the mantle
- the sinking crust will melt under the intense heat and pressure into magma
- magma will then rise thru the cracks of the oceanic crust, pour onto oceanic floor, forming undersea volcanoes
- overtime, they will build up and appear above sea level, forming volcanic islands
- density of the crust is determined by age of crust, older which is located further from centre of spreading will be denser
14
Q
Landform found between CP-CP convergence
A
Fold mountains
15
Q
Fold mountains (CP-CP convergence)
A
- when 2 continental plates collide, the rocks layers along the boundary are compressed
- causes the rock strata/layers to buckle and fold (Anticline and syncline)
- process called folding
- compression continues, layers of sediments are uplifted/pushed upwards to from fold mountains
- e.g. the Himalayas formed between Indian and Eurasian Plate
16
Q
Old Vs New fold mt (location and age)
A
O:
-located far away from current plate boundaries
-formed 200-400 million years ago when Pangaea broke up and continents drifted apart
N:
-located along current plate boundaries
-formed abt 100 mil years ago
17
Q
Old vs New fold mt (shape)
A
O: -lower, rounder -e.g. mountains in Greenland formed abt 400 mil years ago, have smoother and rounder contours -from active erosion and weathering N: -higher
18
Q
Fold mountains example: Himalayas Mountain Range
A
- believed that there was once a large area of sediment that separated Asia and India
- when Eurasian and Indo-Australian move towards each other, the Asian and Indian continental land masses collided
- the sediment between the 2 land masses buckled and folded
- immense folding and uplifting of layers of sediment resulted in the formation of the Himalayan mountains
19
Q
Landforms/features found between OP-CP convergence
A
- Oceanic trench
- Fold mountains
- Volcanoes
20
Q
Oceanic trench (OP-CP convergence)
A
- when an OP collides with a CP, the denser OP is forced to sink into the less dense continental crust
- this will form a long, deep depression in ocean floor known as an oceanic trench
e. g. Australian Plate (O) and Eurasian Plate (C) collide to form the Sunda Trench
21
Q
Fold mountains (OP-CP convergence)
A
- when the 2 plates cllide, causes rock layer along the boundaries to be compressed
- causes rock strata to buckle and fold (process known as folding)
- as compression continues, layers of sediments are uplifted to form fold mountains
- e.g. collision of Oceanic Nazca Plate into the Continental South America
22
Q
Volcanoes (OP-CP convergence)
A
- OP collide with CP, OP forced to sink under CP and into mantle
- melt into magma under intense heat and pressure
- magma rises thru fractures and onto earth’s surface
- piles around vent in successive layers and eruptions to form volcano
23
Q
Conservative/Transform Plate Boundary
A
- formed when 2 plates slide past one another
- results in formation of a transform fault
- fault is a break in Earth’s crust caused by movement of rock
- e.g. San Andreas Fault
- no land is destroyed or created along these boundaries, instead earthquakes occur
24
Q
Earthquakes
A
- as tectonic plates move, exert friction on one another, cause pressure to build up at the boundaries
- pressure gradually builds up in the plates, energy stored in earth’s crust
- when rocks can no longer maintain pressure, energy is released in form of seismic waves
- energy radiates out thru the crust and onto earth;s surface
