Unit C: The Changing Earth Flashcards
Precambrian Era
The first major section of geological time, lasting from the origin of Earth 4.5 billion years ago up to 590 million years ago.
Outcrop
A part of rock formation that appears above the surface of the surrounding land.
Mantle
The layer of earth between the crust and the core.
Plastic
A substance with the properties of a solid that can flow under pressure.
Asthenosphere
The upper most layer of the mantle.
Core
The innermost layer of the consists of a solid inner core and a liquid outer core.
Mesosphere
The part of the mantle beneath the asthenosphere.
Crustal Plate
A large piece of continental crust or oceanic crust that floats and slowly moves atop the asthenosphere.
Paleomagnetism
The study of the magnetic properties of rock formed in a past geological era.
Plate tectonics
The theory that the lithosphere consists of crustal plates that slowly moves across Earth’s mantle and interact at their boundaries.
Sedimentary
Rock formed from compressed layers of pre existing rock or organic matter.
Fossil
The evidence or remains of ancient life preserved in Earth’s crust.
Trace fossil
Indirect fossilized evidence left by ancient organisms rather than the organisms themselves.
Strata
The layered bands within sedimentary rock.
Law of superposition
A law stating that higher strata in a sequence of rock layers are younger than lower strata.
Relative dating
The process of placing rocks and geological structures in the correct chronological order.
Stratigraphic sequence
A sequence of rocks that provides a chronological record of region’s geological history.
Intrusion
A body of rock that forms from the invasion of magma into pre-existing rock formation.
Absolute age
The number of years that have elapsed since an event occurred.
Index fossil
A fossil used to determine the relative age of a layer in a stratigraphic sequences from different locations.
Uniformitarianism
The principle that the geological processes in action today have always fundamentally operated in the same way throughout Earth’s history.
Unconformity
A surface in a rock sequence that represents a break in the pattern due to erosion or lack of deposition.
Rock cycle
A concept that relates the continual change of rocks from one type to another.
Radioactivity
The emission of energy from the nuclei of unstable atoms as they change to become more stable atoms.
Radioactive decay
The disintegration of an unstable atom, which results in the release of energy in the form of radiation.
Half-life
The time taken for half of a radioactive sample to decay, a half life is a constant increment of the time that depends on the particular isotope.
Isotope
A particular variety of an element as defined by its atomic mass.
Fossilization
The process by which any trace of the existence of ancient life is preserved within rocks.
Cyanobacteria
Microscopic, photosynthetic, single-celled bacteria.
Stromatolite
A layered structure built by cyanobacteria.
Burgess Shale
A Cambrian-age rock unit found on the side of Mount Wapta in the Canadian Rockies known for its well-preserved fossils.
Seismogram
A record of seismic waves provided by a seismograph.
Seismograph
An instrument that records seismic waves.
Petroleum Trap
A large quantity of petroleum confined between layers of impermeable rock.
Petroleum
Liquid hydrocarbons formed over millions of years from the remains of ancient microscopic marine organisms.
Seismic Wave
Waves that travel through Earth as a result of explosions or earthquakes.
Fault
A crack in the Earth’s crust due to the motion of one tectonic plate relative to another.
Subduction
The down turning of oceanic crust under another crustal plate.
Focus
The region that first breaks along a fault during an earthquake.
Epicenter
The point on Earth’s surface directly above the focus of an earthquake.
Primary wave or P-Wave
A seismic wave that travels through rock as a series of compression and expansions of particles- A P-Wave is able to pass through solids, liquids and gases.
Secondary wave or S-Wave
A seismic wave that travels through rock as a series of crests and troughs- A S-wave can travel through solids only.
Amplitude
The maximum displacement of a wave from the rest position.
Longitudinal Wave
A wave in which the vibration of the particles is parallel to the direction the wave is travelling.
Transverse wave
A wave in which the vibration of the particles is perpendicular to the direction the wave is travelling.
Richter Magnitude
A number assigned to an earthquake based upon the amount of vertical ground motion as its epicenter.
Tsunami
a seismic sea wave set off by an earthquake in or near an ocean basin.
Pangaea
A single super continent that formed in the late Paleozoic Era.
Cordillera
An extensive chain of mountain ranges that formed the principal range of a continent.
Cenozoic Era
The last 65 million years of Earth’s History.
Glacier
A large river of ice that forms on land and moves under the influence of gravity.
Continental Ice sheet
A very large glacier, often more than 1 km in depth that forms in polar regions.
Mountain glacier
A glacier that forms in mountainous regions at high elevations.
Ice Age
A period during which ice sheets cover parts of the Northern and Southern Hemispheres
Glaciation
A period during which polar ice sheets advance to cover large regions of North American and northern Europe.
Weather
The state of the atmosphere in terms of variables such as temperature, cloud cover, precipitation, and humidity for a particular place at a particular time.
Climate
The average of daily and seasonal weather events that occur in a region over a long period of time.
Hydrosphere
All the water at or near Earth’s surface.
