Plate Tectonics 1
What causes tectonic plates to move under Earth's surface?
Convection currents in the mantle.
Which puzzle-like feature of continents supports plate tectonics?
The jigsaw fit of continental coastlines.
What is the name of the theory that explains how the Moon formed?
The collision theory.
What force initiates the collapse of gas and dust in a nebula to begin star formation?
Gravity.
What physical property of mantle materials causes convection currents to form in Earth's interior?
Differences in temperature and density.
Why do the locations of most volcanoes and earthquakes support tectonic theory?
They occur along plate boundaries.
Describe the sequence of events in the collision theory of Moon formation.
Theia hit Earth, debris was ejected, it orbited Earth, and came together to form the Moon.
Discuss the relationship of a nebula and a stellar nursery.
Some nebulae are formed from the remnants of dying stars, while others are the birthplaces of new stars—these are known as stellar nurseries.
Imagine Earth’s mantle suddenly stopped generating heat from radioactive decay.
What long-term changes might happen to plate movement and surface geology?
If the mantle stopped generating heat, convection currents would weaken or stop. This would cause tectonic plate movement to slow down or cease, resulting in less volcanic activity and fewer earthquakes over millions of years.
Name four pieces of evidence that support the theory of plate tectonics.
Jigsaw fit of coasts, volcano/earthquake zones, fossil distribution, magnetic alignment in rocks.
Why doesn’t the Moon have much iron in its core compared to Earth?
It formed mostly from Earth’s crust and mantle, not its iron-rich core.
What is the term for a forming star in a nebula that hasn’t started fusion yet?
Protostar.
Describe how the Red Sea was formed. Mention ALSO the names of plates involved in its formation.
The Red Sea began to form around 30 million years ago when the Arabian Plate started to pull away from the African Plate. This caused the crust to crack and form rift valleys.
Describe the geological process that creates new oceanic crust and pushes old crust aside.
Seafloor spreading at mid-ocean ridges.
In 2012, Robin M. Canup proposed a new hypothesis. Describe her new hypothesis.
She suggests the Earth and Moon formed together from the impact of two protoplanets, each larger than Mars. The two protoplanets came together to create the Earth and a debris disc from which the Moon formed. (Giant Impact Hypothesis)
What happens inside a nebula to form a star?
Gravity pulls material together, increasing pressure and temperature until nuclear fusion begins.
If there are places where tectonic plates are moving apart and making new crust, why isn’t the Earth growing in size? Mention ALSO the name of the scientist who answered this question.
In the 1960s, a scientist called Harry Hammond Hess proposed that the ocean floor spreads on either side from a mid-ocean ridge like a conveyor belt. Other geologists realised that some ocean crust was being pushed under continents causing the formation of mountain chains and deep ocean trenches (a long, narrow, deep depression in the ocean bed). When the crust is pushed under the continents it becomes part of the mantle.
How do alternating magnetic stripes on the seafloor provide a "timeline" of plate movement?
They record Earth’s magnetic reversals symmetrically on both sides of mid-ocean ridges.
Give 5 pieces of evidence that support the Collision Theory.
1. The stable-isotope ratios of lunar (Moon) and terrestrial (Earth) rock are similar but not identical.
2. the Earth's spin and the Moon's orbit have similar orientations
3. there is evidence in other star systems of similar collisions
4. the Moon has a relatively small iron core – the Moon formed mainly from debris from the outer layers of the Earth which have less iron than the core.
5. the Moon has a lower density than the Earth – the Moon is formed mainly from debris from the Earth’s outer layers, which are less dense than the core.
Give 15 names of nebulae.
Orion Nebula
Eagle Nebula
Crab Nebula
Carina Nebula
Horsehead Nebula
Lagoon Nebula
Trifid Nebula
Helix Nebula
Rosette Nebula
Ring Nebula