Question

unit 3 study guide

1. list the layers of the earth from most dense to least dense.
2. why is the earth in layers?
3. which layer of the earth has both oceanic and continental crust?
4. what state of matter is the mantle?
5. what evidence do we have that the earth is in layers?
6. which of those evidence is measuring how waves travel through different layers?
7. what does the composition of meteorites provide evidence about earth’s structure?
8. describe each layer of the earth by including it’s state of matter and what it’s made of.
9. what is the magnetic field generated by?
10. what drives plate tectonics?
11. how do convection currents cause plate movement?
12. what is the relationship between radioactive decay and plate tectonics?
13. what do you get at a convergent boundary of two oceanic plates?

Explanation:

1. The Earth's layers from most to least dense are inner - core, outer - core, mantle, crust. The inner - core is solid iron and nickel, outer - core is liquid iron and nickel, mantle is semi - molten rock, and crust is solid rock.
2. The Earth is in layers due to the process of planetary differentiation during its formation, with denser materials sinking to the center and less dense ones rising to the surface.
3. The crust has both oceanic and continental types. Oceanic crust is thinner and denser, while continental crust is thicker and less dense.
4. The mantle is semi - molten, also known as plastic or viscous. It can flow slowly over long periods.
5. Evidence for Earth's layers includes seismic waves (P - waves and S - waves) which change speed and direction as they pass through different materials, gravity and magnetic field measurements, and the study of meteorites.
6. Seismic waves are used to measure how waves travel through different layers. P - waves can travel through solids, liquids, and gases, while S - waves can only travel through solids.
7. The composition of meteorites provides evidence about Earth's structure because they are thought to be remnants of the early solar system, similar in composition to the materials that formed the Earth.
8. Inner - core: solid, made of iron and nickel; Outer - core: liquid, made of iron and nickel; Mantle: semi - molten, made of silicate rocks; Crust: solid, continental crust is made of granite - like rocks, oceanic crust is made of basalt - like rocks.
9. The Earth's magnetic field is generated by the movement of the liquid outer - core, which is a process called the geodynamo.
10. Plate tectonics is driven by convection currents in the mantle. Heat from the Earth's interior causes the mantle material to rise, spread, and then sink, moving the tectonic plates above.
11. Convection currents in the mantle cause plate movement as the rising and sinking of hot and cold mantle material exerts a force on the overlying tectonic plates, pushing and pulling them along.
12. Radioactive decay in the Earth's interior provides the heat that drives the convection currents in the mantle, which in turn drive plate tectonics.
13. At a convergent boundary of two oceanic plates, one plate is subducted beneath the other, often leading to the formation of deep - sea trenches and volcanic island arcs.

Answer:

1. Inner - core, outer - core, mantle, crust
2. Planetary differentiation during formation
3. Crust
4. Semi - molten
5. Seismic waves, gravity and magnetic field measurements, study of meteorites
6. Seismic waves
7. Similarity to early Earth - forming materials
8. Inner - core: solid, iron and nickel; Outer - core: liquid, iron and nickel; Mantle: semi - molten, silicate rocks; Crust: solid, continental (granite - like), oceanic (basalt - like)
9. Movement of the liquid outer - core (geodynamo)
10. Convection currents in the mantle
11. Rising and sinking mantle material exerts force on plates
12. Radioactive decay provides heat for mantle convection driving plate tectonics
13. Subduction, deep - sea trenches, volcanic island arcs