What meteorites, Moon rocks and ancient crystals tell us

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Table, Sample ages (USGS), with columns Sample, Age (billion years)

   Meteorites, 4.53 to 4.58; oldest Moon rocks, 4.4 to 4.5; oldest zircon crystals (Western Australia), 4.3 to 4.4; oldest Earth rocks (Acasta Gneiss, Canada), 4.03.

2. 1.

   Order the samples from oldest to youngest, by Bo's reading.

   • Earth's oldest rocks, zircons, Moon rocks, meteorites
   • Zircons, meteorites, Earth rocks, Moon rocks
   • Moon rocks, Earth rocks, meteorites, zircons
   • Meteorites, Moon rocks, zircons, Earth's oldest rocks
3. 2.

   About how much older are the meteorites (about 4.56) than Earth's oldest rocks (4.03 billion years), by Esme's math?

   • About 53 years
   • About 530 million years
   • About 8.6 billion years
   • About 5.3 billion years
4. 3.

   Earth is about 4.54 billion years old, yet its oldest rocks are 4.03 billion. Why the gap, by Jun's reading (USGS)?

   • Plate tectonics has recycled the earliest rocks
   • Earth's first rocks were meteorites that flew back into space
   • The dates must be wrong
   • Earth formed 4.03 billion years ago
5. 4.

   A sample has 1/4 of its parent isotope left. The half-life is 700 million years. About how old is it, by Kira's math?

   • About 1.4 billion years
   • About 175 million years
   • About 700 million years
   • About 2.1 billion years
6. 5.

   A sample has 1/8 of its parent left, with a half-life of 1.3 billion years. About how old is it, by Luz's math?

   • About 10.4 billion years
   • About 2.6 billion years
   • About 1.3 billion years
   • About 3.9 billion years
7. 6.

   USGS says dating uses half-lives from 700 million to more than 100 billion years. Why are such long half-lives useful for these samples, by Milo's reading?

   • Long half-lives stop decaying
   • Short half-lives would be more accurate for old rocks
   • Enough parent is still left to measure after billions of years
   • They measure how far meteorites traveled

8. Table, Sample ages (USGS), with columns Sample, Age (billion years)

   Meteorites, 4.53 to 4.58; oldest Moon rocks, 4.4 to 4.5; oldest zircon crystals (Western Australia), 4.3 to 4.4; oldest Earth rocks (Acasta Gneiss, Canada), 4.03.

9. 7.

   The Moon's oldest rocks (4.4–4.5 billion years) are much older than most of Earth's. Why, by Ren's reading (USGS)?

   • Earth's rocks are older, but they are buried too deep to find
   • Moon rocks are meteorites
   • The Moon has no plate tectonics to recycle them
   • The Moon formed long before Earth
10. 8.

    Tiny zircon crystals from Western Australia are dated to 4.3–4.4 billion years, but their source rocks are gone. What do they show, by Tala's reading (USGS)?

    • Earth had solid crust by about 4.4 billion years ago
    • They formed 4.4 million years ago
    • Earth is just 4.4 billion years old
    • They are meteorites
11. 9.

    Most meteorites that fall are stony, but most found long after falling are irons (NASA). Why, by Zee's reading?

    • Irons are heavier and easier to tell from Earth rocks
    • Iron meteorites fall more often
    • Stony meteorites come from the Sun
    • Irons are younger

12. Table, Sample ages (USGS), with columns Sample, Age (billion years)

    Meteorites, 4.53 to 4.58; oldest Moon rocks, 4.4 to 4.5; oldest zircon crystals (Western Australia), 4.3 to 4.4; oldest Earth rocks (Acasta Gneiss, Canada), 4.03.

13. 10.

    On a timeline where 1 cm stands for 100 million years, how far apart are the meteorite age (about 4.56) and the zircon age (about 4.4 billion), by Ari's math?

    • About 44 cm
    • About 1.6 cm
    • About 16 cm
    • About 0.16 cm