What meteorites, Moon rocks and ancient crystals tell us
Grade 9 Science Worksheet
Circle the best answer.
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.
Order the samples from oldest to youngest, by Bo's reading.
- Meteorites, Moon rocks, zircons, Earth's oldest rocks
- Moon rocks, Earth rocks, meteorites, zircons
- Earth's oldest rocks, zircons, Moon rocks, meteorites
- Zircons, meteorites, Earth rocks, Moon rocks
Earth is about 4.54 billion years old, yet its oldest rocks are 4.03 billion. Why the gap, by Jun's reading (USGS)?
- The dates must be wrong
- Earth formed 4.03 billion years ago
- Plate tectonics has recycled the earliest rocks
- Earth's first rocks were meteorites that flew back into space
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 2.1 billion years
- About 700 million years
- About 175 million years
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 1.3 billion years
- About 3.9 billion years
- About 10.4 billion years
- About 2.6 billion years
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?
- They measure how far meteorites traveled
- Long half-lives stop decaying
- Enough parent is still left to measure after billions of years
- Short half-lives would be more accurate for old rocks
NASA says the Moon's first crust formed about 4.4 billion years ago, from rock that floated up in a magma ocean. Which order fits, by Pia's reading?
- Magma ocean, then the collision
- Collision, magma ocean, then crust
- Crust first, then the collision
- Capture, then a magma ocean
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.
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)?
- Moon rocks are meteorites
- Earth's rocks are older, but they are buried too deep to find
- The Moon has no plate tectonics to recycle them
- The Moon formed long before Earth
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 is just 4.4 billion years old
- They formed 4.4 million years ago
- They are meteorites
- Earth had solid crust by about 4.4 billion years ago
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
- Irons are younger
- Stony meteorites come from the Sun
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.
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 16 cm
- About 0.16 cm
- About 1.6 cm
- About 44 cm