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

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

3. 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.

4. 3.

   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 30 km
   • About 2,200 km
   • About 2,930 km
   • About 5,100 km
5. 4.

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

   • About 3,450 km
   • About 950 km
   • About 6,350 km
   • About 1,250 km
6. 5.

   Earth is about 12,750 km wide (USGS). A 30 km continental crust is what fraction of that, by Milo's math?

   • About 50%
   • About 0.24%
   • About 2.4%
   • About 24%
7. 6.

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

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

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

   • The magnetic field is a solid bar
   • Lava from volcanoes is pure core metal brought up from below
   • 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
   • Huge pressure keeps it solid despite the heat
   • It is made of light rock
10. 9.

    Earth is about 4.54 billion years old. On a 4.54 m timeline (1 m per billion years), how far from the start is a mark for 4.0 billion years ago, by Tala's math?

    • About 4.0 m
    • About 0.54 m
    • About 0.54 mm
    • About 54 m

11. 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.

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