Download See Q. “Sampler” on packet, pages 12

See Q. “Sampler” on packet, pages 12-15
1st Lecture Exam on Tuesday, October 2nd (Multiple Choice)
EVOLUTION OF THE UNIVERSE: GALAXIES
- Milky Way
o Democritus (450-370 BC) gave the first notion of the milky way
o Galileo (1610 BC)
! First to really develop the telescope
! First to really look at space and the milky way
o Georges Lemaitre (1927)
! Came up with the idea of the big bang
o 20-15 BYA: Big Bang
o EP Hubble (1924)
! Looked at the milky way and discovered that there were billions of
galaxies beyond the MW
o G. Gamow (1940s)
! Looked into the evolution of protogalaxies
o Expansion: atomic fusion & cooling
o Gravitational attraction = galaxies formed
- Solar System
o Nebular Theory [Pierre Simon Marquis de LaPlace (1815)]
! Matter became clustered in stars with the outer eddies condensed in
chunks
! A hypothesis concerning the origin of the solar system according to which
a rotating nebula cooled and contracted, throwing off rings of matter that
contracted into the planets and their moons, while the great mass of the
condensing nebula became the sun.
- Earth
o Earth is about 4.6 billion years old
o All planets circle sun in same direction and their orbits lie on the ecliptic plane
o Earth’s formation:
! Planetesimal (chunks of matter) accretion by coalescence
! Internal melting due to
• Gravitational compression
• Impact heating
• Radioactive decay
! Differentiation into layers
• Light material rises to the top (surface)
• Heavy material sinks to the center (core)
! 4.2 to 3.7 billion years ago, crustal cooling & thickening start and
continued until 1,000 million years ago, when crustal plates break up &
begin migrating, initial mechanisms of plate tectonics
• Sea-floor spreading
• Subduction
• SIMA: magnesium silicates
o Crust under mountains are thicker than any other areas (called mountain roots,
allows crust of the continents to extend deeper through the mantle)
Rocks Formation, Classification, and Relationships
• Pockets of magma approach surface and cool -> Igneous
o Weathering: process of breaking down rocks
o Transportation: moves downhill usually and clumps up
• Sediments stack up and the bottom layers become compacted from high pressure
(lithification) -> Sedimentary
• Heat and pressure create Metamorphic
o Deformed rocks from some previous cycle (magma)
o Melting allow the process to start over
Rock Formation
• +/- 100 elements -> 2000+ minerals -> combine to form rocks
o Physical properties
o Chemical properties
o Origin, processes formation
Rock Genesis
• 3 basic groups and 6 sub groups
• Igneous (Intrusive aka plutonic or extrusive aka volcanic)
• Sedimentary (Detrital aka clastic or chemical)
• Metamorphic (foliated or non foliated)
Definitions
• Intrusive (igneous): form inside the crust of the earth = plutonic
• Extrusive (igneous): form on surface of earth = volcanic
• Detrital: chunks of rock from weathering and breaking down that clump up eventually
• Chemical: non chunks
• Foliated: cleavage, parallel lines
Igneous Rocks
• Crystalline structure (even during cooling and solidification)
• Location (internal/external)
• Temperature (cooling rate)
• Speed of formation
• Size of crystals -> strength
• Igneous intrusive rock (plutons, a lot of plutons = batholith)
• Dike: vertical structure
• Sill: horizontal structure
- Burial causes compaction
- Pressure solution along grain contacts
- Deposition of dissolved materials in percolating water and grain residues
Two possible components:
1) Rock Particles (grains)
2) Intergranular cement (also called matrix)
*Their strength and other properties may be different from one another and may affect
further weathering, infiltration, water storage, etc.
Two Sedimentary Rock Types:
1) Detrital (aka Clastic): with rock fragments/grains and cement
2) Chemical: with soluble materials
- These may be precipitated by inorganic or organic (biological) processes
- Organic example: Coral limestone, coal
Detrital
Inorganic
Chemical
Organic
Sedimentary
METAMORPHIC ROCKS
- Metamorphic rocks have been subjected to processes of metamorphism (e.g. heat,
pressure, chemical fluids)
• Contact metamorphism: in close proximity to magma masses, lots of heat
• Regional metamorphism: occurs over extensive areas, especially along
subduction zones
• Hydrothermal metamorphism (least common): contact with thermal waters
*For diagrams of the forms of metamorphism, see textbook
- Metamorphic rocks are also divided by INTENSITY of metamorphism processes
• Low grade metamorphism (minimal alternation)
• High grade metamorphism (significant change)
Metamorphic Rocks
1. Metamorphic rocks are classified by Presence of Foliation
• Foliation
- Cleavage Plains
• Foliated
- Mineral crystals are visibly aligned, rock displays a banded aspect (2+
minerals must be present.)
1. Mainly produced by Compressive Stress
• Non-foliated
- Rocks have one single mineral, and/or have minimal deformation (lowgrade), and minerals have equidemensional crystals (i.e.+- equal
dimensions.
2. Metamorphism Results in Specific Types of Rock (know this)
-
Water is attracted to mineral particles; these have
negatively charged particles
- Water molecules also attach to other water molecules
- Many water layers attach on mineral particles
- Water layers act like wedges, pushing apart mineral
particles. Minerals in rocks are altered and weathered
o Expansion when wet, contraction when dry
• Hydrolysis
- Water molecule splits into 2 ions
- H2O = HO + H
- These ions then combine with minerals
- Occurs more frequently at high temperatures
• Oxidation and Reduction
- Minerals react in the presence or absence of oxygen
- Oxidation: occurs in aerobic (O-rich) environments
o Produces red/yellow/orange colors
- Reduction: occurs in anaerobic (O-deficient) zones
o Produces gray/dark brown/black colors
• Weathering is needed for the development of different sediments and soils
• Main elements in Earth’s crust
o Oxygen (O)
o Silicon (Si)
o Aluminum (Al)
o Calcium (Ca)
o Magnesium (Mg)
o Sodium (Na)
o Potassium (K)
o Iron (Fe)
(SiAlOCaFeKNaMg)
-
Order of relief: difference of elevation
o First-Order landforms
! Oceans and landscapes
o Second-Order landforms
! Features: Major oceans or continent subdivisions
! Examples: mountain ranges, large river valleys, deltas, ocean basins,
marine fans
! Second order includes third order
o Third-Order landforms
! Examples: mountains, glaciers, domes, streams
o Fourth-Order landforms
! Miniature relief: an area with Tafoni, a rock Pedestal, a group of
exfoliated blocks
*Orders of relief includes one another (fourth falls in third, which falls in second…)
* 1st and 2nd order landforms (continents, oceans) are caused by global dymanics (plate
tectonics) over long time periods
* 3rd and 4th order landforms caused by erosion and deposition of materials over shorter
time periods