further developments
However, significant scientific developments since Wegeners death meant they were a giant step closer to being able to reveal and understand the mechanism that drives plate movements.
1. Palaeomagnetism
This looks at the earths past magnetism where Holmes (1978) stated;
‘In past geological ages, the continents occupied positions relative to the poles and to each other, very different from those of today’s unfamiliar geography.’
By constructing lines of equal magnetic inclination, (isoclines) it can be seen that Europe and the British Isles were previously located further south of their present positions, proving the continents have drifted apart over time.
2. Sea-floor Spreading
Magma rises to the crust as a result of convection and creates a new section of sea floor as it cools. This creates mid-ocean ridges which spread the sea floor laterally, with the Atlantic widening by 5cm/year.
3. The discovery of the Mid-Atlantic Ridge
Sea-floor Spreading was concluded after examining rock ages in the centre of the ridge and those towards the USA. In contrast to the original belief that rocks were ancient in origin, the rocks in the centre were newer, younger rocks while those towards the edges were older.
1. Palaeomagnetism
This looks at the earths past magnetism where Holmes (1978) stated;
‘In past geological ages, the continents occupied positions relative to the poles and to each other, very different from those of today’s unfamiliar geography.’
By constructing lines of equal magnetic inclination, (isoclines) it can be seen that Europe and the British Isles were previously located further south of their present positions, proving the continents have drifted apart over time.
2. Sea-floor Spreading
Magma rises to the crust as a result of convection and creates a new section of sea floor as it cools. This creates mid-ocean ridges which spread the sea floor laterally, with the Atlantic widening by 5cm/year.
3. The discovery of the Mid-Atlantic Ridge
Sea-floor Spreading was concluded after examining rock ages in the centre of the ridge and those towards the USA. In contrast to the original belief that rocks were ancient in origin, the rocks in the centre were newer, younger rocks while those towards the edges were older.
A theoretical model of the formation of magnetic striping. New oceanic crust forming continuously at the crest of the mid-ocean ridge cools and becomes increasingly older as it moves away from the ridge crest with seafloor spreading:
a. the spreading ridge about 5 million years ago
b. about 2 to 3 million years ago
c. present-day.
a. the spreading ridge about 5 million years ago
b. about 2 to 3 million years ago
c. present-day.