Rock Types
What type of rock often contains fossils?
Sedimentary
What process forms igneous rock?
Cooling of magma or lava
Where are the oldest layers in an undisturbed rock sequence?
At the bottom
What are the large pieces of Earth’s crust called?
Tectonic plates
Where do most earthquakes occur?
At plate boundaries
Which rock is formed when magma cools slowly underground?
Intrusive igneous rock
What process turns rock into sediments?
Weathering and erosion
What do geologists use to estimate the age of rock layers?
Fossils and rock position (relative dating)
Which plate boundary involves plates sliding past each other?
Transform boundary
Which wave travels fastest: P-wave or S-wave?
P-wave
What are the grains in sandstone like?
Sandstone grains are sand-sized particles (0.0625 to 2 mm) that have been cemented together. They are visible and roughly the same size.
What process turns sediment into sedimentary rock?
Compaction and cementation
If a fossil is found only in one layer, what is it called?
Index fossil
What happens at a divergent boundary?
Plates move apart, and new crust forms
What tool measures seismic waves?
Seismograph
Which rock reacts with acid and contains calcium carbonate?
Limestone
What does melting turn rock into?
Magma
Which type of rock is best for studying Earth's past?
Sedimentary
What force causes tectonic plates to move?
Convection currents in the mantle
Why does Australia have fewer earthquakes than places like Japan?
Australia is in the middle of a tectonic plate
What is the main difference between mudstone and siltstone?
Grain size – siltstone has slightly larger, more visible grains.
Which process causes sedimentary rock to become metamorphic?
Heat and pressure
Why don’t igneous rocks usually contain fossils?
High heat destroys organic material
Name the boundary where one plate sinks under another.
Convergent (subduction zone)
What material allows earthquake waves to travel the fastest?
Steel (or other dense materials like granite)