Question

1. Explain how crustal plate movement creates seamounts and volcanic islands.

2. Identify and describe the causes of deep ocean currents.

3. Explain why and how the Atlantic Ocean is increasing in size.

4. Explain how is the earth's magnetic orientation locked and how it has changed over time.

5. Explain the difference between oceanic plates and continental plates.

Answer 1

1. At mid-ocean ridges, plates are spreading apart and magma rises to fill the gaps. Near subduction zones, plates collide, forcing ocean crust down toward Earth's hot interior, where this crustal material melts, forming magma that rises buoyantly back to the surface and erupts to create volcanoes and seamounts.

2. Surface wind-driven currents generate upwelling currents in conjunction with landforms, creating deepwater currents. Currents may also be caused by density differences in water masses due to temperature (thermo) and salinity (haline) variations via a process known as thermohaline circulation.

3. The Atlantic Ocean grows 1.5 inches wider every year. That's because the tectonic plates undergirding the Americas are separating from those beneath Europe and Africa.

4. When magma cools, the magnetic material aligns with Earth's magnetic field. As it solidifies, it locks the magnetic field orientation like a tiny compass. Based on the rock's magnetism, we can find the magnetic pole orientation.

5. The answer lies in the composition of the rocks. Continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar. By contrast, oceanic crust is composed of basaltic rocks, which are much denser and heavier.

Answer 2

1. At mid-ocean ridges, plates are spreading apart and magma rises to fill the gaps. Near subduction zones, plates collide, forcing ocean crust down toward Earth's hot interior, where this crustal material melts, forming magma that rises buoyantly back to the surface and erupts to create volcanoes and seamounts.

2. Surface wind-driven currents generate upwelling currents in conjunction with landforms, creating deepwater currents. Currents may also be caused by density differences in water masses due to temperature (thermo) and salinity (haline) variations via a process known as thermohaline circulation.

3. The Atlantic Ocean grows 1.5 inches wider every year. That's because the tectonic plates undergirding the Americas are separating from those beneath Europe and Africa.

4. When magma cools, the magnetic material aligns with Earth's magnetic field. As it solidifies, it locks the magnetic field orientation like a tiny compass. Based on the rock's magnetism, we can find the magnetic pole orientation.

5. The answer lies in the composition of the rocks. Continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar. By contrast, oceanic crust is composed of basaltic rocks, which are much denser and heavier.