Exam #1 Flashcards
Geology
the study/science of the Earth
Earth System Concept
Earth is an interconnected system of air, water, rocks, and life; studying it this way provides a holistic approach
System
any part of Earth or the universe that is somewhat isolated and has something that sets it apart from its surroundings
3 types of systems
isolated, closed, open
Isolated
neither matter nor energy is transferred
Closed
energy is transferred, but matter is not
Open
both matter and energy are transferred
4 spheres of Earth
geosphere, biosphere, hydrosphere, atmosphere –> all OPEN systems
Geocentric vs. Heliocentric
Earth-focused (everything revolves around Earth) vs. Sun-focused (everything revolves around the Sun)
Retrograde Motion
motion that is against the norm; planets exhibit this when they slow down and reverse direction briefly
Law of Gravitation
every body in the universe attracts every other body, resulting in elliptical orbit; components of distance and mass
What dictates a planet?
in orbit around the Sun, sufficient mass to assume hydrostatic equilibrium (round shape), has “cleared the neighborhood” of its orbit (planet’s gravity is enough to pull other smaller objects in)
Doppler Effect
light appears red as it moves further away; indicates that the universe is continually expanding
2 types of terrain on the moon
highlands and maria
Highlands
bright, densely cratered regions
Maria
dark regions, fairly smooth lowlands, originated from asteroid impacts and lava flooding surface
Light Years
light traveling at speed-of-light for 1 year; measure of distance, not time
how far light travels in a year
Makeup of the Sun (what we think)
6 concentric layers, 4 make up a sphere and the other 2 are external “gaseous” layers
Layers of the Sun
core (innermost), radiative (surrounds core), convective (energy moves by convection), photosphere (surface layer), chromosphere (low-density gas flaring out from Sun), and corona (forms solar wind)
Plasma
a form of matter in which gas is electrically charged
Coronal Mass Ejection (CME)
powerful storms release solar gas, so hot that they are electrified into a state of plasma, producing a CME
Magnetic field lines become over-energized and snap, causing plasma to soar into space at 2-5 million mph
X-class: strongest
M-class: medium
C-class: weakest
Earth layers
core (inner and outer), mantle, crust
Mechanical units of Earth
lithosphere, Mohorovic Discontinuity, asthenosphere, mesosphere, core
Lithosphere
composes the crust and uppermost part of mantle
Moho Discontinuity
defines the distinction between the crust and the mantle, when the density changes
Asthenosphere
includes the mantle; plastic, deformable and flows a bit
Mesosphere
lowermost part of mantle
Core
outer core (liquid) and inner core (solid)
Continental Plate
made of continental crust, thicker, less dense, stands/floats on asthenosphere
Oceanic Plate
made of oceanic crust, thinner, denser, sinks lower on asthenosphere
Where does subduction occur?
Active margins
Active Margin
has a lot of subduction and tectonic plate activity, leading to earthquakes, volcanic eruptions, etc.
Passive Margin
much less tectonic activity, fewer tectonic events occur
Conduction
heat moves through a solid without physical movement
3 types of plate margins
divergent, convergent, transform (fault)
Divergent margin
spreading centers, where new plate is created, plates move apart
Convergent margin
two plates move together and one is forced under the other (subduction), or two plates collide and one is uplifted
Transform (fault) margin
where two plates slide past each other, grinding together; frequent cause of earthquakes
Wilson Cycle
process of “rift and drift” in which continental crust breaks (rifts) and moves apart (drifts) to form an ocean basin
Magnetic reversals
when magnetic field flips, a new stripe (showing the new polarity) begins –> wider stripes move faster than more narrow ones
What are the two zones for convergent margins?
subduction and collision
Subduction zone
where oceanic lithosphere sinks into asthenosphere
3 options: ocean hits continent and goes underneath, ocean hits ocean and one goes under the other, or continent hits continent and tends to form mountain range
characterized by: deep trenches and chain of volcanic islands at surface
Collision zone
crust of two continents converges
Key point about collision and subduction
collision = subduction = destruction
Where is crust destroyed?
at subduction zones
Stick slip behavior
occurs in transform plate margins; plates stick together due to friction and deform and squish as more pressure is added, before sliding and returning to normal
Where do transform faults occur?
between spreading ridges
What drives plate tectonics?
believed to be because convection currents in asthenosphere are weakly connected to the lithosphere, so plate movement follows this convection
3 potential mechanisms for plate tectonics hypothesis
ridge push, subduction drag, gravity pull
Ridge push
creation of new plate pushes outward
Subduction drag
lithosphere dragged downward pulls plate
Gravity pull
lithosphere sliding down sloped asthenosphere
Geological Time Scale
2 components: first, position in sequence identifies Relative Age, and second, numerical age can be determined by analysis of the products of radioactive decay
Stratigraphy
the study of strata (layered rocks)
Law of Original Horizontality
states that water-laid sediments are deposited in strata that are horizontal or nearly horizontal
Principles of Stratigraphic Superposition
states that any sequence of sedimentary strata was deposited from bottom to top
Unconformity
a substantial break or gap in a stratigraphic series
Types of unconformities
angular, disconformity, nonconformity
Angular
older strata were deformed (tilted, folded) and then cut off by erosion before younger layers were deposited across them
Disconformity
an irregular surface of erosion between parallel strata; implies cessation of sedimentation and erosion but NOT tilting
Nonconformity
strata overlie igneous or metamorphic rock, so you have different rocks or young rocks laid on top of much older ones
Stratigraphic units
rock = formation
time = system
age = period
System
time NOT age chosen to represent a time interval sufficiently great so that such units can be used globally
Period
represents ACTUAL AGE (numerical)
What are some tools used to study geology?
remote sensing, radar and satellites, robotic measurements, GIS, remote vehicles, computer processing and modeling, etc.
What does GIS do?
represents the real world by breaking it up into different slices and categories (elevation, water features, boundaries, imagery, etc.)
Why does it make more sense that Earth revolves around the Sun? (evidence for heliocentric)
daily rising and setting of the Sun, change in seasons, movement of stars across the sky
explain the life cycle of a star
~10 billion years, hydrogen burns to form helium, forming a red giant, which eventually burns out and uses up all the hydrogen, so helium makes the switch to form carbon, forming a white dwarf, then the star burns out and releases the elements into space; alternatively, a supernova can experience gravitational collapse, which creates elements heavier than iron
how is a new Sun produced?
supernova collapses and creates new objects, and gravitational compression of gas at the center of the cloud produces nuclear burning and thus a new sun
where does new lithosphere from?
at spreading centers (new crust comes from the mantle, spreads outward from the mid-ocean ridge)
what do wide-age stripes indicate?
faster movement than narrower ones
Rule of Original Continuity
strata were originally deposited in continuous layers, and “missing pieces” were removed later
