How Earth formed and separated into layers

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   Earth, average (NASA), 5,514; crust rock, about 3,000. NASA gives Earth's average density as 5,514 kg/m³, while crust rock is near 3,000 kg/m³. What does this show, by Bo's reading?

   • Earth's crust is mostly iron
   • Earth's inside must be much denser than its crust
   • Earth is the same density throughout
   • The inside must be lighter than the crust, since it is so hot
2. 2.

   A mixture of oil, water and sand is shaken and left to settle. How is this like early Earth, by Esme's reading?

   • Densest sinks, lightest floats, as iron sank and rock rose
   • Layers appear without any settling
   • The lightest part sinks, as the crust did
   • Shaking makes the layers, as earthquakes did
3. 3.

   Cutaway with blobs of iron in molten rock. Molten iron is denser than molten rock. In a partly molten young Earth, which way would it move, by Jun's reading?

   • It sinks toward the center
   • It escapes into space through the crust
   • It stays where it is
   • It rises to the surface

4. Read this first

   Table, Earth's layers (USGS), with columns Layer, Thickness, State

   Crust, about 5 km (oceans) to 30 km (continents), solid, brittle; mantle, about 2,900 km, hot, semi-solid rock; outer core, about 2,200 km, liquid iron-nickel; inner core, about 1,250 km, solid iron-nickel.

5. 4.

   Using the USGS table, about how far is it from the surface to the top of the core under a continent, by Kira's math?

   • About 5,100 km
   • About 2,200 km
   • About 2,930 km
   • About 30 km
6. 5.

   Using the table, about how thick is the whole core (outer plus inner), by Luz's math?

   • About 1,250 km
   • About 3,450 km
   • About 6,350 km
   • About 950 km
7. 6.

   Why does Earth have a magnetic field while the Moon has almost none today, by Noah's reading?

   • The Moon's surface blocks its field
   • Earth has a large, moving liquid outer core
   • Earth's solid inner core spins on its own
   • Earth's crust is made of strongly magnetic rock
8. 7.

   Scientists find the outer core is liquid and the inner core solid. Which evidence shows this, by Pia's reading (USGS)?

   • Lava from volcanoes is pure core metal brought up from below
   • The magnetic field is a solid bar
   • Drilling down to the core
   • How earthquake waves travel through the layers
9. 8.

   Cutaway of the inner core labeled 5,400 °C. NASA gives the inner core a radius of about 1,221 km and a temperature as high as 5,400 °C (9,800 °F). Why is it solid, by Ren's reading?

   • It is cold, below freezing
   • It is liquid, like the outer core
   • It is made of light rock
   • Huge pressure keeps it solid despite the heat

10. Table, Earth's layers (USGS), with columns Layer, Thickness, State

    Crust, about 5 km (oceans) to 30 km (continents), solid, brittle; mantle, about 2,900 km, hot, semi-solid rock; outer core, about 2,200 km, liquid iron-nickel; inner core, about 1,250 km, solid iron-nickel.

11. 9.

    The mantle has more iron and magnesium than the crust (USGS). How does that fit the sorting story, by Zee's reading?

    • The mantle should be the lightest layer, floating above the crust
    • Denser, iron-richer rock settled below the lighter crust
    • The crust should hold the most iron
    • The layers have no differences
12. 10.

    Which statement about the lithosphere is right, by Ari's reading (USGS)?

    • It is the crust alone, 2,900 km thick
    • It is the liquid outer core
    • It is the rigid crust plus the upper mantle, at least 80 km thick
    • It is the inner core's surface