Earth Science Earthquake-Time-Volcano
Terms
undefined, object
copy deck
- Radioactive decay
- The breakdown of a radioactive element, releasing particles and energy.
- Law of Superposition
- The geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it.
- Cinder Cone
- A steep, cone-shaped hill or mountain made of volcanic ash, cinders, and bombs, piled up around a volcano's opening.
- Composite volcano
- A tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials.
- Index Fossils
- Fossils of widely distributed organisms that lived during only one short period.
- Shield Volcano
- A wide, gently sloping mountain made of layers of lava and formed by quiet eruption.
- Unconformity
- A place where an old, eroded rock surface is in contact with a newer rock layer.
- Epicenter
- The point on Earth's surface directly above an earthquake's focus.
- Focus
- The point beneath Earth's surface where rock breaks under stress and causes an earthquake.
- P wave
- A type of seismic wave that compresses and expands the ground.
- S wave
- A type of seismic wave that moves the ground up and down or side to side.
- Surface Wave
- A type of seismic wave that forms when P waves and S waves reach Earth's surface.
- Absolute Age
- The age of a rock given as the number of years since the rock formed.
- Era
- One of the three long units of geologic time between the Precambrian and the present.
- Pangaea
- The name of the single landmass that broke apart 225 million years ago and gave rise to today's continents.