How Earth formed and separated into layers

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   a hot, mixed young Earth, then a layered Earth. Why did Earth separate into layers, by Ari's reading?

   • Earth formed in layers from the start
   • Dense iron sank and lighter rock rose while Earth was molten
   • Light rock sank to the center
   • The Moon's pull stacked the layers
2. 2.

   What had to happen before Earth's iron could sink to the center, by Bo's reading?

   • Earth had to be hot enough to partly melt
   • Nothing; the layers were there from the start
   • The iron had to float to the top
   • Earth had to cool and freeze solid

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.

   Which material ended up at Earth's center, by Kira's reading (USGS)?

   • A giant magnet that makes the magnetic field
   • Light crust rock
   • Iron and nickel
   • Water
5. 4.

   Which layer is liquid, by Jun's reading (USGS)?

   • The outer core
   • The inner core
   • The crust
   • Each layer
6. 5.

   About how thick is the crust under the oceans, by Luz's reading (USGS)?

   • About 500 km
   • About 5 km
   • About 2,900 km
   • About 1,250 km
7. 6.

   What creates Earth's magnetic field, by Milo's reading (USGS)?

   • The spinning liquid outer core
   • A giant bar magnet in the crust
   • The Moon
   • The solid crust's iron rocks

8. 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.

9. 7.

   Which order runs from least dense to most dense, by Noah's reading?

   • They are equally dense
   • Core, mantle, crust
   • Crust, mantle, core
   • Mantle, crust, core
10. 8.

    Lighter material rose as Earth sorted itself. Which layer did it form, by Ren's reading?

    • The inner core
    • The outer core
    • The crust
    • No layer; it sank
11. 9.

    Timeline ruler in billions of years. About how old is Earth, by Tala's reading (USGS)?

    • About 4.54 million years
    • About 4.54 billion years
    • About 6,000 years
    • About 13.8 billion years, the universe's age
12. 10.

    Which formed first: the solar system's oldest solids or Earth's layers, by Zee's reading?

    • Earth's layers came first
    • Earth formed long before the Sun
    • They formed in the same instant
    • The oldest solids, then Earth and its layers