Term
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Definition
Sedimentary Cover
Igneous/Metamorphic Basement |
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Term
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Definition
| loose fragments of rocks or minerals, mineral crystals that precipitate from water solution, and shells formed from organisms. |
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Definition
| forms at or near surface from cementation of loose grains, precipitation of minerals from solution, or cementation of shell fragments. |
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| Random facts about sedimentary rocks |
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Definition
•! Less than 1% of Earth’s mass but cover 80% of Earth’s surface.!
•! Form a veneer or ‘cover’ over igneous and metamorphic ‘basement’ rock.!
•! Sedimentary basin—area where sedimentary cover is several kilometers thick.!
•! Contains historic record of Earth surface history (including biological history).!
•! Bulk of energy resources (coal, petroleum) come from sedimentary rocks.! |
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Term
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Definition
| processes that break up and/ or corrode solid rock, eventually transforming it into sediment.! |
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Term
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Definition
•! Two main types: physical and chemical (plumbing snake vs. drano).!
•! Physical (mechanical) weathering—breakup of rocks into unconnected grains or chunks (detritus).! |
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Term
| Physical Weathering: Jointing |
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Definition
•! Jointing—natural cracks formed in rocks due to cooling or removal of overburden.!
–! Exfoliation—formation of onion-like sheets parallel to rock surface. Common in granites.! |
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Term
| Physical Weathering-Talus |
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Definition
| accumulation of loose bedrock blocks forming an apron of rubble at the base of a slope.! |
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Term
| Physical Weathering-Wedging |
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Definition
–! Frost wedging—expansion of joint by ice.!
–! Root wedging—expansion of joint by root.!
–! Salt wedging—expansion of joint by precipitated salt crystals.! |
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Term
| Physical Weathering- thermal expansion |
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Definition
| weathering driven by intense heating (e.g. forest fire).! |
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Term
| Chemical Weathering-Dissolution |
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Definition
Dissolution—minerals dissolved by water.!
–! Salts and carbonate minerals most affected.!
–! Can be a function of acidity.!
–! CO2 from decaying organic matter is main source of acidity—CO2 + H2O = H2CO3.!
–! Leads to formation of karst.! |
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Term
| physical/chemical weathering in concert |
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Definition
WEATHERING IN CONCERT!
•! Physical and chemical weathering usually work as a team.!
•! Physical weathering aids chemical weathering by creating surface area.!
•! Chemical weathering aids physical weathering by weakening the attachments between grains.! |
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Term
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Definition
| Rocks resist weathering at rates relative to their composition making some rocks more resistant to weathering than others.! |
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Term
| Sedimentary Rock Type: Clastic (detrital) |
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Definition
Clastic (detrital): cemented-together fragments and grains derived from pre-existing rocks. Commonly silicate minerals!
–! Siliciclastic! |
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Term
| Sedimentary rock type: Chemical |
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Definition
Chemical: composed of minerals that precipitate from water solutions. Usually talking about carbonates, e.g., limestone!
–! Biochemical: made up of shells of organisms.! |
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Term
| Formation of Clastic Rocks |
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Definition
•! Sedimentary rocks form in five steps:!
–! Weathering creates sediment.!
–! Erosion removes sediment from source.!
–! Transportation moves sediment by wind, water, or ice to a new location.!
–! Deposition allows sediment to settle from its transporting medium.!
–! Lithification transforms loose sediment into rock.! |
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Term
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Definition
Clast Size and Character
Boulders and Cobbles!
Angular Boulders!
Sand (quartz and feldspar)!
Silt!
Clay/mud!
Rock Name
Conglomerate!
Breccia!
Sandstone!
Siltstone!
Shale! |
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Term
| Carbonate rocks, a.k.a. limestone! |
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Definition
! Carbonate minerals precipitate in clear warm water under low pressure, thus...!
–! Common in low latitudes!
–! Common in shallow water!
–! Not much siliciclastic sediment (carbonates don’t grow at the mouth of the Mississippi)!
•! Look for carbonates anywhere there is clear shallow water in low latitudes! |
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Term
| CHEMICAL SEDIMENTARY ROCKS! |
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Definition
•! Many marine organisms have ability to extract ions from seawater and form mineral shells!
–! Corals, algae, clams, oysters, and snails! –! Chalk: microscopic carbonate plankton shells, e.g.,
forams!
•! After organisms die the shells may become incorporated into sedimentary rock.!
–! CaCO3 preserved in shallow water whilst SiO2 stable in deep water! |
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Term
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Definition
! Composed of cryptocrystalline (microscopic) quartz. !
•! Formed from accumulation of plankton that grow silica shells (diatoms and radiolaria).!
•! Shells later dissolve and re-crystallize to form cryptocrystalline quartz.! |
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Term
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Definition
Evaporites: formed by evaporation of saltwater. Evaporation removes water, but ions stay behind, eventually building up to mineral precipitation.!
•! Bonneville Salt Flats, Utah: salt beds deposited by ancient evaporating lake, i.e., lake with inlets but no outlets (closed basin).!
•! May also occur in restricted marine basins, e.g., Mediterranean.! |
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Term
| Other chemical rocks: dolostone and travertine |
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Definition
•! Dolostone—formed by replacing calcite in limestone with dolomite CaMg(CO3)2!
•! Travertine—calcite precipitation associated with springs. Saturated water drips and slowly deposits layers of carbonate in layers. Common in caves and near hot springs! |
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Term
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Definition
• Metamorphic rock forms from pre-existing rock, or protolith.
• Metamorphic rocks have undergone some type of distortion in composition and structure below the surface.
• Metamorphism—the process of forming new rock by heat, pressure, or stress.
• Metamorphism is a solid-state process: – Does not involve significant melting – Weathering is not considered metamorphism
• Metamorphic rocks often contain unique minerals, which grow under metamorphic temperatures and pressures.
• Metamorphic rocks may also possess special textures, such as the preferred alignment of mineral grains. |
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Term
| Metamorphic Processes: Recrystallization |
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Definition
| changes the shape or size of mineral grains without changing their identity |
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Term
| Metamorphic processes: Metamorphic reaction |
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Definition
| grows new mineral crystals through chemical reactions with protolith crystals. |
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Term
| Metamorphic processes: phase change |
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Definition
| transforms a grain of one mineral to another mineral of a different crystal structure but the same composition (polymorphs) |
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Term
| Metamorphic processes: pressure solution |
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Definition
| occurs when rock is squeezed more strongly in one direction than another, causing chemical reactions along grain boundaries, and causes grains to grow longer in one direction than another |
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Term
| Metamorphic processes: plastic deformantion |
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Definition
| minerals deform like soft plastic at high temperatures to form new crystal shapes of the same mineral |
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Term
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Definition
• Heat: High temperatures cause bonds between atoms to break and rearrange, leading to recrystallization or metamorphic reactions.
• Most metamorphic reactions occur between 200°C and 850°C, but the upper range varies depending on rock composition, pressure, and water content.
• Temperatures in the Earth vary depending on the geothermal gradient and proximity to igneous activity.
– e.g. 500°C may occur at 25 km depth or 250 m depth near an intrusion |
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Term
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Definition
• When differential stress is applied to a rock platy or elongate minerals may align in the same direction.
• Orientation may develop through pressure solution, plastic deformation, or compression.
– Platy—pancake-shaped crystals – Elongate—cigar-shaped crystals – Equant—roughly same dimensions in all directions
• Foliation is the alignment of platy minerals in metamorphic rocks. |
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Term
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Definition
| slight metamorphism of shale slightly aligns internal minerals = foliation |
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Term
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Definition
Coarser grained rock, contains visible crystals of micas. Schistosity is an alignment of mica crystals resembling fish scales.
• Higher temperature and with larger crystals than phyllite.
• May contain other minerals including quartz, feldspars, and garnets. |
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Term
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Definition
Contains compositional layering often manifest as light and dark banding.
• Represents separation of felsic minerals (light layers) with mafic minerals (dark layers).
• High temperature and pressure rock. |
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Term
| Non-Foliated Rock-Quartzite |
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Definition
Contains compositional layering often manifest as light and dark banding.
• Represents separation of felsic minerals (light layers) with mafic minerals (dark layers).
• High temperature and pressure rock. |
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Term
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Definition
• Marble: forms from recrystallization of limestone or dolostone.
• Uniform texture and relative softness of calcite makes marble ideal for sculpting.
• Impurities create aesthetically pleasing banding. |
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Term
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Definition
•! The earth, was ~6000 years old
•! Landforms probably formed as a result of the great flood
•! Earth formed October 23rd 4004 BC
–!James Ussher, 1654 |
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Term
| Da Vinci on fossils (early 1500’s) |
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Definition
•! They resembled living shells.
•! Found too far from the ocean to be carried by a flood
•! Found like living shells, not jumbled up from flood deposits
•! He was correct, but ignored. |
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Term
| Nicolaus Steno (1638-1686 ) |
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Definition
The prodromus of Nicolaus Steno's dissertation concerning a solid body enclosed by a process of nature within a solid
• Fossils were deposited with the sediments
• Superposition-In undeformed sediments, the oldest layer lies at the bottom, youngest at the top.
• Original Horizontality:
•! Most stratification is horizontal
–!Particles settle from a fluid under the influence of gravity
•! Inclined strata must have been disturbed
• Lateral Continuity
! Strata were once laterally continuous –!to a certain extent.... |
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Term
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Definition
•! Gentleman Farmer
•! Concerned with soil, where it came from, where it was going.
Main Ideas:
•Crosscutting relationships
Something that cuts across another must be younger than the material that’s being cut.
–You can’t cut bread if it ain’t there yet!
•! Faulting--break in rock w/ movement
•! Igneous intrusions--dikes, sills, plutons
• Principle of inclusion
particles of other rocks are included in rock formation
• Unconformities
•The Rock Cycle
(Deposition, Erosion, Upheaval, Deposition)
•Hutton noticed the weathering of rocks (soil)
•Sedimentary rocks were made of bits of weathered older rocks.
•The unlithified counterparts to the strata were still forming and would eventually form rocks.
•Revolution: a cyclic view |
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Term
| Unconformity (Gaps in Record) |
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Definition
An unconformity is a period of non- deposition and/or erosion, representing missing time in the rock record.
•Unconformities come in three varieties:
–Angular unconformity: rocks below unconformity are
tilted or folded.
–Nonconformity: sedimentary rocks overlie igneous or metamorphic rocks.
–Disconformity: unconformity occurring between otherwise flat layers of sedimentary rocks.
• Can be difficult to detect
How can you find subtle unconformity?
•! A marker that will tell us the “age” of the rocks.
•! Fossils as time indicators
•! Principle of Fossil Succession –!aka Faunal Succession –!aka Biotic Succession |
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Term
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Definition
•! Speculated that fossils might be useful for correlating rocks from place to place
•! Roman coins were used to date successive human historical events
•! fossils could be used in the same way |
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Term
| George Cuvier (1769-1832) |
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Definition
| •! Recognized that fossils seemed to occur in a particular sequence |
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Term
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Definition
Fossil Succession
1.No two species are exactly alike
2. Once species become extinct they never reappear (exactly the same way)
•Thus, fossils, or assemblages of fossils, can be diagnostic of a certain age
–Index fossils
•! Widespread
•! Short-lived
Fossils are used for relative age dating The fossil succession depends on two assumptions:
•No two species are exactly alike.
•Once species become extinct they never reappear (exactly the same way).
- An index fossil provides reliable correlations between stratigraphic units because it is:
Distinctive Geographically Widespread
Restricted to a narrow time interval |
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Term
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Definition
Sedgwick and Murchison (British)
–Realized the need to “organize” the vast amount of stratigraphic data
•Proposed the idea of naming “systems” of rock
–Based on fossil content and other lithologic criteria |
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Term
| Geological Systems: Cambrian and Silurian |
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Definition
• Sedgwick named the Cambrian system –!Few index fossils –More “lithologic” in nature
•Murchison named the Silurian System –!Based on fossil content
•Debate!!
–Cambrian the lower part of the Silurian?
–Silurian the upper part of the Cambrian?
Debate resolved! •! Charles Lapworth (in 1879)
–Showed that there were THREE distinctive groups of fossils:
•Cambrian (older)
•ORDOVICIAN (intermediate fossils)
• Silurian (younger) |
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Term
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Definition
• “Absolute” time = a real numerical age of the rock being dated
–The use of the radioactive decay of certain elements to date the rock, with an error factor (+/-) |
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Term
| Charles Lyell (1797-1875") |
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Definition
•! Articulated Hutton#s ideas" –!The Principles of Geology (~1830)"
•! Lots of observation and examples" •! Presented in a “lawyer-like” fashion"
–!Darwin#s teacher" |
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Term
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Definition
! Evolution by natural selection
–!A reasonable hypothesis on why fossil succession worked
–!Profoundly influenced by Lyell and gradualism •! In his view, evolution proceeded so slowly
as to be imperceptible to humans –!Required an old earth |
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Term
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Definition
Radioactivity, aka radioactive decay, is the method by which unstable atoms reconfigure nuclei into more stable configurations
Parent Isotope -->Daughter Isotope + Decay Particle + Energy
Some isotopes are stable, but others may be unstable–radioactive.
For example, carbon has 3 isotopes:! !12C has 6 protons and 6 neutrons–STABLE! !13C has 6 protons and 7 neutrons–STABLE! !14C has 6 protons and 8 neutrons–RADIOACTIVE! |
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Term
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Definition
•! The time it takes for half a given group of radioisotopes to decay is called the half-life.
–! Parent = that which decays –! Daughter = decay product
•! Half-lives are determined by laboratory observation, and are constant for a given isotope.
•! The regular decay of atoms is like the ticking of a clock that can measure time.
–! I.e., the proportion of parent-daughter isotopes in a given sample is unique with time.
•! Selection of an isotope system to analyze depends on the scale of time you are attempting to measure, and the availability of minerals that contain appropriate parent- daughter systems. |
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Term
| Modern Uniformitarianism: “Actualism” (~1920’s-today) |
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Definition
•! Uniformity in kind, but not rate
–!Uniformitarianism in the laws of nature (physics) that govern geological processes, though the Earth has changed greatly and at different rates throughout time. |
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Term
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Definition
| cosmology-study of universe |
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Term
| Heliocentric vs. Geo-Centric |
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Definition
•Early models for the universe were geo-centric i.e. had the Earth as the center of the universe
• The heliocentric model puts the sun at the center of the universe (of our solar system, actually)!
– Planets orbit around the Sun
• The geocentric model held for nearly 2,000 years until Copernicus published a new justification of the heliocentric model in the 16th century
With the next generation of scientists came
heliocentric model!
new data to support the idea:
– Kepler demonstrated elliptical orbits for the
planets, further falsifying the geocentric model!
– Using the newly invented telescope, Galileo observed Venus had phases similar to our Moon’s—a phenomena possible only in the heliocentric model |
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Term
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Definition
•! Approximately 13.7 billion years ago, the universe was packed into an infinitesimally small, infinitely dense, infinitely hot point of pure energy....
•! The Big Bang marked the beginning of the expansion of this point
–!Within one second the Universe had expanded and cooled to the point where subatomic particles (protons and electrons) could form
–!Within 3 minutes, with a diameter of 60 billion miles, and a temperature below 1 billion degrees, nuclei of new atoms began to form from hydrogen fusion
–!Termed “big bang nucleosynthesis”, this process is capable of forming very light elements (H, He, Li), and all nuclei capable of forming by this process would have done so within 5 minutes |
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Term
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Definition
• 1920s astronomers measured light spectra of distant galaxies
These light spectra displayed pronounced ‘red shifts’
•Astronomers concluded that these red shifts were the result of the Doppler effect!
–“Phenomenon in which the frequency of wave energy appears to change when a moving source of wave energy passes an observer.” |
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Term
| Formation of Solar System |
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Definition
•! Astronomers concluded that these red shifts were the result of the Doppler effect!
–!“Phenomenon in which the frequency of wave energy appears to change when a moving source of wave energy passes an observer.”! |
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Term
| Order of planets: Mr. VEM J SUN |
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Definition
| Mars, Venus, Earth, Mercury, Jupiter, Saturn, Uranus, Neptune |
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Term
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Definition
Light travels at speed of 300,000 km per second
One light year = 6 trillion miles
Astronomical Units= 1 A. U- distance from earth to sun, about 93 million miles |
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Term
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Definition
| .387 AU from Sun, 88-day orbit, temps to 450 C |
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Definition
| .723 AU from sun, 225 day orbit, thick acidic atmosphere, temps to 550 C |
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Definition
| Differentiation- separation of materials by density, occured after melting when portoplanet earth was hot |
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Term
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Definition
1.52 AU from sun
687 day orbit
thin atmosphere
temps -140 to 20 C |
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Definition
5.2 AU from sun
4333 day orbit
10 hour rotation
massive, H & He rich, nebular composistion similar |
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Definition
9.53 AU from sun
10,756 day orbit
ice-dust ring system |
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