Geology 1013 Exam 2
Parent isotope
Unstable radioactive isotope
Anticline folds
Upfolded or arched layers
Rift valley
Deep canyon along the crest of a ridge resulting from tensional forces
Composite cones/stratovolcanoes
Large, symmetrical cones built by layers of of cinder and ash alternating with lava flows
Conformable
Layers of rock that have been deposited without interruption
Seismology
The study of earthquake waves
Earthquake
The sudden movement of one block of rock slipping past another along a fault
Focus
Where the slip begins
Asthenosphere
The hotter, weaker mantle below the lithosphere
Seafloor spreading
The process by which new seafloor is created along the ocean ridge system
Fossils
The remains or traces of prehistoric life
Paleontology
The scientific study of fossils
Orogenesis
The set of processes that forms a mountain belt
Relative dates
determined by placing rocks in the proper sequence of formation
Hot spot
An area of volcanism, high heat flow, and crustal uplift above a mantle plume
Lithosphere
Crust and uppermost (coolest) mantle
Volcanic cone
Formed by successive eruptions
Alpha particle
2 protons and 2 neutrons
Disconformity
A break in sedimentary rock strata representing a time when erosion occurred
Oceanic Ridge System
A continuous underwater mountain range with parts found in every ocean of the world
Mantle plume
A cylinder of upwelling hot rock
Magnitude
A quantitative measure of energy released in an earthquake
Hot-spot track
An area in the Earth's mantle from which hot plumes rise upward, forming volcanoes on the overlying crust
Deformation
All changes in shape, position, or orientation of a rock mass
Richter scale
Amplitude of the largest seismic wave
Core
An iron-nickel alloy
Syncline folds
Associated downfolds or troughs
Subduction zones
Boundaries that mark the collision between two of the planet's tectonic plates
Electron capture
Captured by the nucleus and combined with a proton to form a neutron
Elastic rebound
Causes deformed rock to spring back to undeformed position
Domes
Circular or elongated upwarped structures
Slab pull
Cold, dense oceanic crust sinks because it is denser than the asthenosphere
S waves
Do not travel through liquids or gasses
Basins
Downwarped structures
Hadean
Earliest eon of Earth history (before the oldest known rocks)
Epicenter
Earth's surface directly above the hypocenter
Beta particle
Electron from the neutron
Precambrian
Eons and eras before the Phanerozoic
Volcanic necks (plugs)
Eroded volcanic cones expose the solidified magma inside the conduit
Lava
Erupted magma
Inclusions
Fragments of one rock unit enclosed within another
Volatiles
Gases in magma
Tsunami
Generated when megathrust displacement lifts large slabs of seafloor and displaces water
Ridge push
Gravity causes lithospheric slabs to slide down the ridge
Unconformity
Interrupting the deposition of sediment creates a break in the rock record
Daughter isotope
Isotope resulting from radioactive decay
Asymmetrical folds
Limbs are different
Symmetrical folds
Limbs are mirror images
Fracture zones
Linear breaks in the seafloor
Outer core
Liquid that generates Earth's magnetic field
Deep ocean trenches
Long, linear depressions; result of subduction
Plates
Major separate blocks that make up the Earth's surface
Seismometers
Measure earthquake waves
Moment magnitude
Measures total energy released based on amount of slide, area of rupture, and strength of faulted rock
Magma
Molten rock containing crystals and dissolved gas
Continental rifting
Occurs when divergent boundaries develop within a continent
Overturned folds
One or both limbs are tilted beyond the vertical
Alfred Wegner
Outlined the hypothesis of continental drift
Radiometric dating
Reliable method of calculating ages of rocks
Eons
Represent the greatest span of time
Viscosity
Resistance to flow
Compressional forces
Result in shortening and thickening of the crust
Reverse polarity
Rocks with opposite magnetism
Normal polarity
Rocks with the same magnetic field as today
Pangea
Single supercontinent of all the Earth's land
Inner core
Solid sphere
Fault creep
Some segments displace slowly with little shaking
Uniformitarianism
States that the physical, chemical, and biological laws that operate today have also operated in the geologic past
Faults
Structures formed by brittle deformation
Cinder cones
Symmetrical, steep-sided, loose accumulations of ejected scoria
Paleomagnetism
The branch of geophysics concerned with the magnetism in rocks that was induced by the earth's magnetic field at the time of their formation
Half-time
Time required for one-half of the nuclei in a sample to decay
Surface waves
Travel in rock layers just below Earth's surface
Body waves
Travel through Earth's interior
P waves
Travel through solids, liquids, and gasses; travel faster than S waves
Divergent boundaries
Two plates move apart
Convergent boundaries
Two plates move together
Transform plate boundaries
Two plates slide past each other
Radiocarbon dating
Using the carbon-14 isotope to date very recent events
Pumice
Vesicular rock from andesitic or rhyolitic magma
Scoria
Vesicular rock from basaltic magma
Pipes
Volcanic necks that carried magma from depths more than 150m below the surface
Folds
Wavelike undulations that form when rocks bend under compression
Nonconformity
Younger sedimentary rocks on top of older metamorphic or intrusive igneous rocks