1.3 Continental Drift

Why are earthquakes rare in ocean basins away from MORs?

Why is there a positive heat flow over the axial rift of an MOR?

How have satellites provided evidence for sea floor spreading?

[blank_start]Transform[blank_end] faults displace mid-ocean ridges. They form [blank_start]perpendicular[blank_end] to the axial rift.

Seismic [blank_start]tomography[blank_end] has been used to provide evidence for mantle plumes and hot spots by taking [blank_start]3D[blank_end] images of heat flow to show areas of [blank_start]high[blank_end] heat flow compared to cooler ones.

Label the image to show the formation of island chains and seamounts over a hotspot.

How does a chain of islands and seamounts develop over a hotspot? Rising magma creates an [blank_start]island[blank_end]. The plate moves over the [blank_start]hotspot[blank_end]. The mantle plume is [blank_start]stationary[blank_end]. Older islands [blank_start]sink[blank_end] and are eroded.

What is a mantle plume?

Using the fit of Africa and S. America describe the evidence for the movements of continents over time. Fit of the [blank_start]continents[blank_end] - Fit along edge of continental [blank_start]shelf[blank_end]. - Few [blank_start]overlaps[blank_end] due to younger rock deposited. - Few gaps due to [blank_start]erosion[blank_end]. Rock types - Matching [blank_start]rock[blank_end] sequences across the join of the continents - Same age of rocks across the [blank_start]join[blank_end] eg. Precambrian - cratons eg. Carboniferous - [blank_start]glacial deposits[blank_end] Mountain chains - Same trend of mountain [blank_start]belts[blank_end] across the join of the continents - structures such as folds / faults match up - same rock types in the mountain belt across the join - same [blank_start]age[blank_end] of mountains across the join Fossils - outcrops of fossils match up / same fossils on different continents - fossils that could not have crossed an ocean the same on both continents eg reptile - [blank_start]Mesosaurus[blank_end] eg plants - [blank_start]Glossopteris[blank_end] Glaciations - direction of [blank_start]striations[blank_end] shows movement of ice and the striations match up - glacial [blank_start]erratics[blank_end] can be found on both continents - glacial rocks match up across the join - Carboniferous ice [blank_start]sheet[blank_end] can be seen across Africa and South America

Fossils found in Africa and S. America used as evidence for continental drift: Reptile = [blank_start]Mesosaurus[blank_end] Plant = [blank_start]Glossopteris[blank_end]

Label the diagram of an MOR.

Label the diagram of the oceanic-continental convergent plate margin.

Label the diagram of the continental-continental convergent plate margin.

Label the diagram of a oceanic-oceanic convergent plate margin.

Give examples of the different types of plate margins: Divergent: [blank_start]Mid-Atlantic Ridge[blank_end] Oceanic-Continental Convergent: [blank_start]Nazca[blank_end] and [blank_start]South American[blank_end] Continental-Continental Convergent: [blank_start]Indian[blank_end] and [blank_start]Eurasian[blank_end] Oceanic-Oceanic Convergent: [blank_start]Pacific[blank_end] (subducting) and [blank_start]Philippine[blank_end] Conservative: [blank_start]Pacific[blank_end] and [blank_start]North American[blank_end]