PPT: Divergent Plate | Crash Course for UPSC Aspirants PDF Download

 Page 1


GEOGRAPHY 
CRASH COURSE
CAPSTONE IAS LEARNING
Page 2


GEOGRAPHY 
CRASH COURSE
CAPSTONE IAS LEARNING
Divergent Boundary
• In Plate Tectonics, we have learnt about the major and minor 
lithospheric plates and how these plates moved through the 
geological past.
• We have studied about convection currents in the mantle which 
are the primary reason behind plate movements ? divergence and 
convergence of the lithospheric plates.
• The horizontal limbs of the convection currents, just below 
the lithosphere, drag the plates horizontally.
• The falling limbs of the convection currents create a negative 
pressure on the lithosphere, and this negative pressure (pulling 
force) is responsible for the formation of the convergent boundary.
• The rising limbs, on the other hand, create positive pressure on the 
lithosphere, and this positive pressure (pushing force) creates a 
divergent boundary.
Page 3


GEOGRAPHY 
CRASH COURSE
CAPSTONE IAS LEARNING
Divergent Boundary
• In Plate Tectonics, we have learnt about the major and minor 
lithospheric plates and how these plates moved through the 
geological past.
• We have studied about convection currents in the mantle which 
are the primary reason behind plate movements ? divergence and 
convergence of the lithospheric plates.
• The horizontal limbs of the convection currents, just below 
the lithosphere, drag the plates horizontally.
• The falling limbs of the convection currents create a negative 
pressure on the lithosphere, and this negative pressure (pulling 
force) is responsible for the formation of the convergent boundary.
• The rising limbs, on the other hand, create positive pressure on the 
lithosphere, and this positive pressure (pushing force) creates a 
divergent boundary.
Evolution of a Divergent Boundary
Page 4


GEOGRAPHY 
CRASH COURSE
CAPSTONE IAS LEARNING
Divergent Boundary
• In Plate Tectonics, we have learnt about the major and minor 
lithospheric plates and how these plates moved through the 
geological past.
• We have studied about convection currents in the mantle which 
are the primary reason behind plate movements ? divergence and 
convergence of the lithospheric plates.
• The horizontal limbs of the convection currents, just below 
the lithosphere, drag the plates horizontally.
• The falling limbs of the convection currents create a negative 
pressure on the lithosphere, and this negative pressure (pulling 
force) is responsible for the formation of the convergent boundary.
• The rising limbs, on the other hand, create positive pressure on the 
lithosphere, and this positive pressure (pushing force) creates a 
divergent boundary.
Evolution of a Divergent Boundary
Stage 1: Upwarping, fault zones
• Rising limbs of the convection currents create 
a plume that tries to escape to the surface by 
upwarping the lithosphere (doming the 
lithosphere upwards).
Page 5


GEOGRAPHY 
CRASH COURSE
CAPSTONE IAS LEARNING
Divergent Boundary
• In Plate Tectonics, we have learnt about the major and minor 
lithospheric plates and how these plates moved through the 
geological past.
• We have studied about convection currents in the mantle which 
are the primary reason behind plate movements ? divergence and 
convergence of the lithospheric plates.
• The horizontal limbs of the convection currents, just below 
the lithosphere, drag the plates horizontally.
• The falling limbs of the convection currents create a negative 
pressure on the lithosphere, and this negative pressure (pulling 
force) is responsible for the formation of the convergent boundary.
• The rising limbs, on the other hand, create positive pressure on the 
lithosphere, and this positive pressure (pushing force) creates a 
divergent boundary.
Evolution of a Divergent Boundary
Stage 1: Upwarping, fault zones
• Rising limbs of the convection currents create 
a plume that tries to escape to the surface by 
upwarping the lithosphere (doming the 
lithosphere upwards).
Stage 2: Rift Valley Formation
• Faulting due to divergence creates extensive rift system (fault zones, 
rift valleys).
• The lithosphere is subject to a horizontal extensional force, and it will 
stretch, becoming thinner (E.g. The crust above Yellowstone 
hotspot is thinning because of mantle plume).Eventually, it will 
rupture, leading to the formation of a rift valley.
• This process is accompanied by surface manifestations along the rift 
valley in the form of volcanism and seismic activity.
• Rifts are the initial stage of a continental break-up and, if successful, 
can lead to the formation of a new ocean basin.
• An example of a place on Earth where this has happened is the South 
Atlantic Ocean, which resulted from the breakup of South America and 
Africa around 138m years ago.