Emergence of ocean basins

Who was the first person to propose the theory of continental drift

Alfred Wagner - the theory was largely rejected due to lack of mechanism explanation

Where is the oceanic crust formed and destroyed

Formed at the spreading centre, destroyed by melting following subduction

What drives convection cells in the asthenosphere

Heat from radioactive decay

What are 4 observations directly related to crustal motion

Geographical variability of crustal heat flow, geographical variability of the thickness of deep-sea sediment, geographical location, magnetic anomalies

How do heat flow measurements change with distance from the spreading centre

Decreases in temperature away from the spreading centre

Where are earthquake epicentres concentrated along

Ocean ridged, transform faults, trenches, volcanic island arcs,

How does earthquake magnitude change a different positions on the sea floor

Highest at trenches due to impression from subduction

lowest at ridges due to spreading

What 2 factors show decreasing heat flow through the ocean crust

Increasing distance from the spreading surface

Increasing age of crust

What does the Vine-Matthews-Morley hypothesis show records of

Record of reversals in basaltic rock

What does the VMM hypothesis state

New ocean crust is formed at ocean ridges and magnetic orientation is reserved

Therefore

Magnetometer records should reveal magnetic anomalies and should show a stride pattern parallel to the ridges

What is the Hawaiian island chain an example of

Oceanic crust moving over stationary hotspots

What happens to young vs old islands in the Hawaiian

Younger islands are active, whilst older islands subside as they cool