deas Flashcards
Term/Front
Definition/Back
(Radioactive Decay) Absolute Dating
As an unstable atomic nucleus (core
of an atom) attempts to become
stable, it sheds an alpha particle
(protons and neutrons) and emits
radiation
• This causes original atomic nucleus to
become a new atomic element
– This process is called radioactive
decay and it will continue until the
forces in the nucleus are balanced
and stable
Similarities and differences between Midlatitude and Tropical cyclones
Both have low-pressure centers.
Both cause heavy rain and strong winds.
Midlatitude Cyclones: Form in temperate zones, need cold and warm fronts.
Tropical Cyclones: Form over warm tropical waters, powered by ocean heat.
Uniformitarianism
The Earth has gradually changed over time
– That said, the processes that have shaped the Earth have not changed
– “The present is the key to the past”
The Geologic Time Scale
Rocks can be used to piece together
Earth’s history
• The challenge is putting the pieces in
the correct order.
Relative Dating
Compare rocks or events to other rocks or events to determine
which is older/younger
– Can’t determine the exact age using this methodology
Absolute Dating
Determines the age of rocks or events in terms of actual years* (e.g.,
2.4 million years old)
(Stratigraphy) Relative Dating
Branch of geology concerned with the order and relative position of
strata (layers of rock) and their relationship to the geological time scale
Superposition Relative Dating
This is the most basic principle of relative dating
– In undeformed stratigraphic sequences, the oldest strata will lie at the
bottom of the sequence, while newer material is above
(Unconformity) Relative Dating
A break/gap in time within the rock record
– Many unconformities are due to sea-level changes, sea-level has
fluctuated hundreds of feet over time
(Lateral Continuity) Relative Dating
Layers of sediment (and the rock layers they form) extend laterally in
all directions when first deposited
– So, similar rock layers that are separated by valleys or other erosional
features can be assumed to have been originally continuous
Fossil Succession) Relative Dating
This is what was used to create The
Geologic Time Scale
– Different types of fossils appear in a
predictable sequence through
geological time (i.e., each fossil
species has a unique age range)
– Index Fossil
• Commonly found fossils with a very
narrow age range
(Correlation) Relative Dating
Matching up rock layers from
different locations to determine if
they are the same age, even if they
are geographically separated
• Do this by comparing features like rock
type, fossil content, and sedimentary
structures
– Can create a complete record in
some cases despite unconformity
at particular locations
Radioactive Decay (Continued)
– Half-life
• The time it takes for half the mass of a
radioactive isotope to decay into the
daughter product
– Can range from fractions of a second
to billions of years
Dating the Rock Record
Have to use BOTH relative and
absolute dating methods when
looking at an actual rock record
Folding
The process by which rocks bend instead of break when stress is
applied, creating wave-like structures
• Rocks are typically deposited in flat horizontal sheets, but folding will cause
these to warp into new directions
Rock Cycle
Magma cools to make igneous rocks -> metarmorphism and weathering -> sediments -> erosion -> sedimentary rock -> metamorphic rock -> melting -> magma
Metamorphic Rocks (Non-Foliated)
not foliated it does not a have any banding stripes or layers
Earth’s Oldest Mineral
4.4 Billion Years)
Precipitation
is falling water/ice
All precipitation originates from
parcels of moist air rising (cooling adiabatically)
steps for precipitation
Parcels cool until saturation is reached, thus allowing for condensation – Clouds form from condensed moisture – Over time accumulated moisture can fall (precipitation)…
For precipitation we need two things: – 1. – 2.
Moisture in the air
A mechanism to cool the air – This is necessary to cause condensation, such as rising air, which cools and allows water vapor to condense into droplets, eventually leading to precipitation.
Air Mass Thunderstorms form when the following three conditions are met:
Sufficient Moisture – There must be enough moisture in the atmosphere to form clouds and precipitation.
Atmospheric Instability – The air must be unstable, meaning that warm air at the surface can rise easily through cooler air above, allowing convection to occur.
A Lifting Mechanism – There needs to be a trigger, such as surface heating, that forces the warm air to rise and form the thunderstorm.
Frontal Uplift Cold Front
If a cold air mass (dense) approaches a warmer air mass (less dense), the cold air will “bulldoze” the warmer air vertically
Frontal Uplift – Warm Front
If a warm air mass (less dense) approaches a colder air mass (more dense), the warm air mass will ride up over the cooler air
Orographic Lifting
Air rises over mountains, cools, and causes rain on the windward side; the leeward side stays dry.
Convectional Uplift
Warm air rises, cools, and condenses, often causing thunderstorms and heavy rain.
Severe Thunderstorms Defined as severe when (at least 1) of the following occur:
Hail
Tornado
Winds reach 58 mph or higher
Severe thunderstorms form when three conditions are met:
Sufficient Moisture
Atmospheric Instability – Warm air can rise rapidly through cooler air above
Lifting Mechanism – A trigger, like a front or intense surface heating, forces the air to rise.
Lightning
is electric discharge from thunderstorm based on charge differences in atmosphere during a thunderstorm (not fully understood)
Thunder
produced by rapid expansion and compression of air by lightning bolt
Hail
Precipitation phenomena – Ice crystals pass through subfreezing and above-freezing layers collecting water
Tornado
– Small vortex of air – Associated with very low pressure – Descends down from the wall cloud at the base of the thunderstorm – Winds can range from 110 mph – 200 mph+
Dissipating stage (E)
– Once the storm has elevated all warm air
Midlatitude Cyclones
Surface large scale low pressure systems –
Central pressure near 990 to 1000 mb •
Jet streams usually responsible for formation and movement* •
Exists between 35-70° latitude •
Converging counterclockwise circulation (Northern Hemisphere) –
Rising motion • Circulation creates fronts
Jet Streams
Fast flowing upper air (neartropopause) currents – Polar jet stream • Found between large boundaries of warm and cold air in the midlatitudes
Life Cycle of a Midlatitude Cyclone:
Early stage (A and B) – Open wave stage (C) – Occlusion stage (D) – Dissipating stage (E)
Early stage (A and B)
Stationary front is prominent •
Separating cold air mass and warm air mass –
Beginning of the formation of the surface low due to divergence aloft –
Winds begin to circulate around the center of low pressure
Open wave stage (C)
During this stage the system has well-defined fronts •
Cold Front • Warm Front
Occlusion stage (D)
Eventually, the surging cold front will catch up with the warm front
– Warm air begins lifting from the surface as the cold “dense” air forces it upwards
– Occluded front created
– Cyclone starts to weaken or “dissipate”
Tropical Cyclone
Low surface pressure system •
Thrive off warm waters (Tropics)
– “Warm core system” •
Typically form between 5-25° latitude
Converging counterclockwise circulation (Northern Hemisphere)
Eye –
located in the center of a hurricane – Generally calm/clear condition
Eyewall
towering ring of cumulonimbus clouds that surrounds the eye
Rapid rising motion from just outside of the eye fuels these storms – Strongest winds, heaviest rainfall
• Rainband
convective bands of heavy precipitation that spirals inward toward the center of the storm
what is banding
banding is a type of foliation with alternating thick layers with different mineral compositions
Crystal form
unique shape of crystals
Define Rocks
Made up of a combination of minerals
• Three main types:
– Igneous
– Sedimentary
– Metamorphic
Metamorphic Rocks (Foliated)
Foliated (striped, distinct sheets of minerals)
• Banding
High-grade metamorphic rocks
rocks have been chemically altered which Results in large changes in chemical composition
Mohs hardness Scale
Talc - softest
Diamond - Hardest
Low-grade metamorphic rocks
rocks have been physically altered so then the minerals rearranged into a more compact form
How many directions of cleavage if there are 2 parallel sides?
1 direction of cleavage
Metamorphic Rocks
Rocks Form when other rock types are subject to metamorphism agents (heat, pressure, and/or exposure to fluids)
– Changes rocks without melting them
Define Fracture
Has no cleavage
What’s more important mineral color or streak color?
Streak color
Sedimentary Rocks (Chemical)
– Can form in many different ways…
– The most common process is called precipitation
• Form solid crystals from a solution of water and dissolved minerals (not cementing pieces together)
Specific Gravity
mineral’s density
Sedimentary Rocks (Clastic)
– Form through lithification (75 percent of sedimentary rocks)
• Rock deposits become buried
• Older layers at the bottom experience “compaction”, water squeezed out
• Minerals dissolved in the water are left in the “pore spaces” between the sediment
• “Cementation” occurs as the minerals fuse the sediment pieces together
What is Sedimentary Rocks( 2 types of weathering and def)
•Rocks Formed from pieces of pre-existing rocks or pieces of onceliving organisms
– These are the types of rocks that make up fossils!
– Mechanical weathering (breaking down rocks through physical stress)
– Chemical weathering (breaking down rocks from some type of chemical reaction)
Hardness
hardness of mineral (talc vs. Diamond)
Extrusive Igneous Rocks
• Form when lava cools rapidly above the Earth’s surface
• Small crystals (sometimes none)
– Aphanitic texture
• Example: Obsidian
Fracture/Cleavage
How a mineral breaks (planes of
weakness)
Streak
color of mineral in powdered form
Intrusive Igneous Rocks
• Form when magma cools slowly below the Earth’s surface
• Large, well-formed crystals
– Phaneritic texture
• Example: Granite
Luster
how light is reflected from a mineral (i.e., general
aesthetic)
Mafic Igneous Rocks
• Rich in magnesium and iron
• Often darker in color
• High density rocks
Felsic Igneous Rocks
• Rich in silica and lighter elements like sodium and potassium
• Often lighter in color
• Low density
Color
color of mineral (least useful property)
Crystal form
unique shape of crystals
What are Igneous Rocks
Rocks formed directly from molten material (magma or lava) or volcanic debris
– Form through crystallization
• When molten material/debris cools and solidifies
By def. all minerals must be
be found in nature
be made up of totally inorganic substances
have the same chemical composition wherever found
contain atom arranged in random pattern and forming solid units called crystals
Deep Mantle Plumes (what is a hotspot)
“Hot Spot” – A place where a deep mantle plume (relative hot spot in mantle) has burned through the crust
• Results in geologic activity (e.g., volcanoes and earthquakes*) despite not being near a plate boundary
Minerals
-A naturally occurring inorganic solid with a definite chemical
structure
-Building blocks of rocks
Plate Tectonics (Transform boundaries)
– Two plates slip past each other laterally
– Neither creates nor destroys crust
– Commonly produce shallow earthquakes
Elements
Building blocks of minerals
• Most of the Earth’s crust is made up of just eight elements
(Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium, Oxygen, Silicon)
Plate Tectonics (Convergent Boundaries ->Continental-Continental)
• No subduction since both plates are highly buoyant
• Builds huge mountain ran
• Volcanoes are rare
• Shallow earthquakes are relatively commonages (e.g., Himalaya Mountains)
Global Warming Disagreements
– Whether the warming since 1950
has been dominated by human
causes
– How much the planet will warm in
the 21st century
– Whether we can afford to
dramatically reduce carbon dioxide
emissions AND whether a reduction
will “improve” the climate
– How big of a danger the issue is
Plate Tectonics (Convergent Boundaries ->Oceanic-Oceanic)
• Subduction results in undersea trench formation (e.g., Mariana Trench)
• “Volcanic island arc” can be created near the boundary
• Deep and shallow earthquakes tend to form along boundary
Plate Tectonics (Convergent Boundaries ->Oceanic-Oceanic)
• Subduction results in undersea trench formation (e.g., Mariana Trench)
• “Volcanic island arc” can be created near the boundary
• Deep and shallow earthquakes tend to form along boundary
Global Warming Agreements
– Surface temperatures have
increased since 1880
– Humans are adding carbon dioxide
(and other greenhouse gases) to
the atmosphere
– Greenhouse gases have a warming
effect on the plane
3) Axial Procession
– Wobbling on axis
– 25,000 years
Plate Tectonics (Convergent Boundaries ->Oceanic-continental)
• Oceanic plate sinks since more dense; subduction
• Forms oceanic trench where subduction occurs
• Volcano formation near boundary (“Continental volcanic arc”)
– This can create mountain ranges (e.g., Cascades and Andes)
• Earthquakes occur along margin • Forms metamorphic rocks – blueschist
2) Orbital Eccentricity
– Higher eccentricity = more elliptical
– Lower eccentricity = more circular
– 100,000 years
Plate Tectonics (Convergent Boundaries)
– Collisions between plates
– “Destructive”
– Three primary collisions:
• 1) Oceanic-continental
• 2) Oceanic-oceanic
• 3) Continental-continental
1) Axial Tilt
– Ranges from 22° – 24.5°
– 40,000 years
Plate Tectonics (Divergent Boundaries)
– Plates move away from each other
– “Constructive”
– Shallow earthquakes and volcanic activity
– Example: Mid-Oceanic ridge
Plate Boundaries
-plate boundaries is border between 2 plates
– Three types:
• Divergent
• Convergent
• Transform
3 Milankovitch Cycles
1) Axial Tilt
2) Orbital Eccentricity
3) Axial Procession
Plate Tectonics
-plate tectonic is Theory behind how and why continents move
• “how” - lithospheric plates float on the asthenosphere
• “why” - CONVECTION!
Holocene
– 10,000 years ago to present
– Interglacial period
What is continental drift (give an example and who made it)
– Continents move (“drift”) on Earth’s surface
– Alfred Wegener Pangaea (225 million years ago)
Pleistocene
– 1.7 million years ago to 10,000 years ago
– Glacial and Interglacial periods
The Ocean Basins (System of ridges)
System of ridges surrounded by reliefs
– Often found at the center of an ocean basin (“Mid-Oceanic Ridge”)
– Active submarine volcanism and major movements of Earth’s crust are found here
• Associated with a divergent plate boundary (more on this later)
Proxy Data
• Historical accounts
• Ice cores
• Sediment cores
• Pollen spores
• Fossils
• Tree rings
The Ocean Basins (Abyssal Zone)
– Abyssal plains is large expansions of low relief ocean floor
• Form the floors of the deepest areas of each ocean
– Depths greater than 5,000 m (16,500 ft)
• Contains numerous hills, valleys, and seamounts
Direct observations
• Climate information from instrumentation
• Have this dating back to 1850s
2 main sources of climate data
Direct Observation and Proxy Data
The Ocean Basins (Continental Rise Margin)
– Transitional zone of gently sloping seafloor
– Begins at the foot of the continental slope and continues
• Extends to depths of approximately 4,000 m - 5,000 m (13,000 ft - 16,500 ft)
– Made of material carried down from shelf and slope
– Leads into the Abyssal zone
What is the Earths age?
4.6 billion years
(Little evidence of early climate (billions of years ago)
– More information about last 2 million years)
The Ocean Basins (Continental Slope Margin)
– Begins where the continental shelf ends and plunges (“slopes”) steeply downward
• Extends to depths of approximately 3,200 m (10,500 feet)
Climate Classification of Salisbury, MD(A,B,C,D,E,H)
mid-Atlantic region of the United States, which generally falls under the humid subtropical climate classification in the Köppen system. Salisbury’s climate can be classified as Cfa:
C: Temperate (Mild Mid-Latitude).
f: Significant precipitation in all seasons (no dry season).
a: Hot summers.
The Ocean Basins (Continental Shelf Margin)
– Gently sloping, relatively shallow, submerged plain at the edge of the continent
• No deeper than 180 m (600 ft)
– Can be relatively large
Oceanic Crust
• Thickness is approximately 5 km (3 miles)
• Mafic “igneous” rocks
– More dense
– Tend to be darker
H: Highland Climates
Climates affected by altitude, with temperatures generally colder as elevation increases.
Precipitation and temperature vary greatly with altitude.
Example: The Andes, Rocky Mountains.
Continental Crust
• Thickness is approximately 40 km (25 miles)
– Behaves almost like a root system to continent above
• Felsic “igneous” rocks
– Less dense
E: Polar Climates
Extremely cold with temperatures often below freezing year-round.
Includes tundra (ET) and ice cap (EF) climates.
Example: Antarctica (EF), northern Alaska (ET).
D: Continental Climates (Severe Mid-Latitude)
Large seasonal temperature differences, with cold winters.
Usually found in the interior of continents.
Example: Moscow, Russia.
Rheology Model (Mantle/Crust)
• Mohorovicic “Moho” Discontinuity
– Discovered in 1909
– Andrija Mohorovicic
• Croatian scientist
– Distinctive contact plane between the Crust and Mantle
• Iron-rich minerals (Mantle) vs. Silicarich minerals (Crust)
C: Temperate Climates (Mild Mid-Latitude)
Moderate temperatures, with distinct seasonal variations.
Winters are mild; summers may be warm.
Subdivisions include humid subtropical (Cfa) and Mediterranean (Csa).
Example: Southeastern United States (Cfa), Mediterranean coast (Csa).
Rheology Model (Crust)
– Lies directly above the Mantle
– Rocks with silica
-rich minerals are dominant here
• Exact composition of the crust is highly variable from place to place (more on this later)
– Thickness varies
• 5 km to 40 (or more) km (3 miles to 25 miles)
- Crust and solid part of upper mantle make up the “Lithosphere”
Rheology Model ( Upper Mantle)
– Same materials as lower mantle, but density is less
– Extends from the base of the crust to a depth of just 660 km (410 miles)
– Interacts with the Crust
– Two parts of Upper Mantle:
• 1) Lower part (Asthenosphere):
– Consists of molten rock
• 2) Upper part:
– As you approach the surface, It becomes more rigid
B: Dry Climates
Characterized by very low precipitation.
Includes deserts (BWh) and semi-arid regions (BS).
Example: Sahara Desert (BWh), which stands for a hot desert climate.
Rheology Model -> (Lower Mantle)
– Composed of rocks with iron
-rich minerals
– More solid than most parts of the Upper Mantle
– Material can slowly move • Movement similar to a glacier
– 2,240 km (1,392 miles) thick
A: Tropical Climates
Warm temperatures year-round.
Significant rainfall, especially during the wet season.
Examples: Amazon Rainforest, Southeast Asia.
Rheology Model -> (Outer Core)
– Consists of the same materials as the inner core
– Pressures are less, so a liquid (molten) state prevails
– Approximately 5,000 Celsius (9,032 F)
– 2,270 km (1,410 miles) thick
Köppen Climate Types
The main categories are designated by capital letters (A, B, C, D, E, and H):
A: Tropical Climates
B: Dry Climates
C: Temperate Climates (Mild Mid-Latitude)
D: Continental Climates (Severe Mid-Latitude)
E: Polar Climates
H: Highland Climates
Climatology
The scientific study of climate, which encompasses the long-term patterns and averages of weather conditions over extensive periods, generally over 30 years or more.
Rheology Model -> (Inner Core)
-Iron and nickel exist here in a dense solid state due to high pressures
-Approximately 6,000 Celsius (10,832 F)
-Radius of only 1,216 km (755 miles)
Earth’s internal layers -> Rheology
based on how different materials flow (e.g., behavior of material)
Meteorology
The scientific study of the atmosphere that focuses on short-term weather patterns and conditions, typically on a scale of hours to weeks.
Earth’s internal layers -> Chemical
– based on rock type
What is Geology?
The science that deals with the Earth’s physical structure and substance, its history, and the processes that act on it
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