Q1. What is the approximate age of Earth?
Evidence from Earth materials and meteorites indicates that Earth formed about 4.54 billion years ago.
Science
Quiz: Earth Through Deep Time
Sample questions from this book. Open the app for the full chapter quizzes and final exam.
Q2. What does the principle of superposition usually tell geologists about undisturbed sedimentary layers?
In an undisturbed sequence, lower sedimentary layers were generally deposited before the layers above them.
Q3. Which process forms metamorphic rock?
Metamorphic rocks form when existing rocks are changed by heat, pressure, or chemically active fluids without fully melting.
Q4. What commonly happens where an oceanic plate sinks beneath another plate?
At a subduction zone, oceanic crust descends into the mantle; this process can also generate volcanoes and deep ocean trenches.
Q5. Why is the geological record described as incomplete?
Erosion may remove rock layers, and later heat or pressure may alter them, leaving gaps in the preserved record.
Q6. What process built the early Earth from smaller bodies in the solar system?
Accretion is the gradual growth of a body as smaller particles and objects collide and combine.
Q7. What happened during Earth’s differentiation?
As much of the early Earth melted, dense metals moved inward and lighter rocky materials rose, forming internal layers.
Q8. Which explanation is currently the leading model for the Moon’s origin?
The leading model proposes that a large body struck the young Earth and that orbiting rocky material gathered to form the Moon.