Tectonic processes

Question 1

Endogenic processes

Answer 1

Geological processes that occur beneath the surface of the Earth, associated with energy originating in the interior of the solid earth. The forces within the earth that cause the ground to move are called endogenic forces. Main processes: folding, faulting and tectonic movements.

Question 2

Plate tectonic theory/continental drift

Answer 2

the gradual movement of the continents across the earth’s surface through geological time.
Alfred Wegener, 1911, all continents were once joined together in a large supercontinent called Pangaea and they split up and drifted apart.

Question 3

Convection currents

Answer 3

Created in the mantle by heat radiating outwards from the inner core. Mantle material, mostly peridotite is under pressure due to depth and when heated behaves like a viscous liquid. Convection in the iron rich outer core creates magnetic field ehich is responsible for paleomagnetism of oceanic crust (proof for sea floor spreading) and for protecting earth from solar radiation.convection currents generated by radioactive decay in the core
The sun heats the earth’s surface, then, when cooler air comes into contact with it, the air warms and rises, creating an upward current in the atmosphere. That current can result in wind, clouds, or other weather. Convection currents within the earth move layers of magma, and convection in the ocean creates currents.
arthur holmes proposed that radioactive decay in mantle generates heat creating convection currents which moved the plates, explain sea floor spreading
Dan McKenzie suggested there are two layers in the mantle each of which are in motion ‘viscosity of the lower mantle’ 1966

Question 4

Evidence for continental drift

Answer 4

Evidence: east coast South America and west coast Africa fit like a jigsaw, remains of the Permian Mesosaurus found in Africa and Brazil, rocks of similar age and type formation a nd structure in Brazil an South africa, plant of Carboniferous period in india and antarctica, appalachian mountains of USA match north west european mountains, climatology: coal beneath antarctic ice cap and evidence of glaciation noted in tropical brazil and central india

Question 5

Evidence for plate tectonic theory

Answer 5

• Maurice Ewing, 1948, Mid Atlantic Ridge, rocks were volcanic and recent so plates move further apart as new ocean lithosphere is formed at ridge and ocean basin gets wider
• Palaeomagnetism
• sea floor spreading

Question 6

Paleomagnetism

Answer 6

• 1950s, underwater volcanic eruptions basaltic lava intrude and during cooling, minerals aligned themselves alogn earth’s magnetic field, magnetic field reverses periodically with 171 reversals over 76 million years, new basalt formed when magnetic pole in north, would aligned to north, after reversal, new in south, almost symmetrical, plootting palaeomagnetic polar changes shows all continents moves across earth oer time

Drummond Matthews and Fred Vine revealed a pattern of magnetic anomalies running in parallel stripes and symmetrically on either side of ridge, assumed magnetic field had reversed its polaristy repeatedly over time

Question 7

Rayleigh-Benard Theory

Answer 7

Rayleigh Benard Theory: The Rayleigh Benard convection phenomena is an instability which basically occurs in a viscous fluid layer submitted to a vertical negative temperature gradient, in the same direction than the gravity.
Rayleigh-Bénard convection (RBC) is the buoyancy-driven flow of a fluid heated from below and cooled from above.