Learn the 8 most abundant elements in the Earth's crust and the chemical symbol of each. See p. 33 in your textbook.
O, Si, Al, Fe, Mg Ca, K, Na
Explain how the Earth changed from a homogeneous blob into a zoned Earth? This process is called differentiation. When did this happen? What data do geologist's use to figure this out?
The Earth got hotter and the blobs began to sink into the center of the Earth to create a core. Differentiation started to occur when radioactivity started to heat up the earth. Geologists use the age of rocks and their recorded magnetic fields.
How old is Earth? Because differentiation occurred sometime after Earth actually formed - the oldest rocks are younger than the age of Earth. What material is dated to determine Earth's age? The age of Earth is the same as the age of the Solar System.
The Earth is 4.6 Billion years old. The age of Earth is determined by meteorites that have fallen to Earth, the age of rocks on Earth, and the age of the solar system.
What would the surface of Earth be like if there were no tectonic activity?
The Earth's surface would be smooth.
Describe the ways that continental crust differs from oceanic crust.
Continental crust is thicker and Oceanic crust is denser.
Be able to list the 5 parts that comprise the exact definition of a mineral that geologists use.
1. Naturally Occurring
2. Inorganic
3. Solid Crystalline
4. Specific Chemical Composition
5. Ordered Internal Structure
Explain why you are not surprised that silicates are the most abundant minerals in the crust (and form most rocks)?
Because some of the most abundant minerals in Earth's crust are Silicon and Oxygen.
Explain how tetrahedron can form lots of different Silicate minerals using this basic building block.
Ions are similar in size and can sub out for each other. The silicate structure determines the properties of the mineral.
What do geologists use to identify minerals? What is the difference between cleavage and crystal form?
Physical properties, crystalline structure, hardness, crystal form, cleavage, fracture, and specific gravity. Cleavage is breakage among smooth surfaces and crystal form occurs naturally.
How many atoms are shared in a silicon-oxygen tetrahedron to form a sheet silicate? What about a single chain?
Strong silicates are within the sheet, 4 for tetrahedron, 2 sharing oxygen atoms for single chain
Be able to explain why diamond and graphite are polymorphs? What is similar about these two minerals and what is different? Why?
Both have the same compositions, different structures, Minerals which have the same chemistry but different crystal structures are called polymorphs, its all in the way carbon atoms are arranged
What are ferromagnesian minerals? What color are they?
They are silicate minerals, for the most part their colors are dark green, black, and dark grey.
What is an isotope?
An isotope is any form of a chemical element that has the same number of protons in the nucleus, or the same atomic number, but has a different number of neutrons in the nucleus.
What rock types are in the rock cycle? Which rock groups form by internal Earth processes and which form by external Earth processes (which rocks can you see forming)? Explain why the rocks found around our campus are mostly metamorphic?
Metamorphic, Igneous, Sedimentary ... metamorphic and igneous are internal Earth Processes while Sedimentary is external. The rocks around Appalachian are metamorphic because of ancient volcanos and plate shifts.
What two properties must you observe to identify an igneous rock? Which one differs between plutonic and volcanic rocks? Explain why?
Texture and composition. The texture between plutonic and volcanic rocks are different. Plutonic rocks are formed underground when magma cools, while volcanic occurs above ground.
Describe different types of intrusive bodies.
Batholith: a large irregular discordant intrusion
Chonolith: an irregularly-shaped intrusion with a demonstrable base
Cupola: a dome-shaped projection from the top of a large subterranean intrusion
Dike: a relatively narrow tabular discordant body, often
What causes rocks to melt within the Earth to form magma? Why is heat alone not enough to usually melt rocks to form magma?
Radioactivity causes the heat and changing the rocks melting points causes them to melt even though the Earth itself isn't hot enough to do so.
What happens to magma during cooling to form so many different kinds of igneous rocks? Hint: use the terms differentiation and crystal settling
The different elements present in the different igneous compositions will form different minerals. *need to use differentiation and crystal settling
Explain why obsidian isn't a volcanic rock made of minerals.
Obsidian is not a mineral because there is no crystalline structures and there is no definite chemical composition. It is simply lava which solidified quickly enough to remain glassy instead of forming mineral crystals.
Why are extrusive rocks fine-grained? Why do vesicles occur uniquely in volcanic rocks?
-their rapid cooling at or near the surface did not provide enough time for large crystals to grow
-When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes fi
What determines the viscosity of lava?
High or low silica contents, gas content, and temperature
Three extrusive rocks are rhyolite, andesite, and basalt. Explain how each differs.
rhyolite- igneous rock, felsic silica-rich, usually pink or gray in color , grains very small, made up of quartz, plagioclase, and sanidine, with minor amounts of hornblende and biotite.
Andesite- igneous rock, a dark, fine-grained, brown or grayish volca
Where does pillow basalt form?
mid-ocean ridges, oceanic hot-spot volcanoes, Ex- Hawaiian Islands
How can volcanoes change the weather? What type of eruption is responsible for this and what is the volcanic material erupted?
The gases and dust particles thrown into the atmosphere during volcanic eruptions have influences on climate. Volcanoes have also caused global warming over millions of years. Some of them, such as ash and sulphur dioxide, have a cooling effect, because t
Why are there no active volcanoes in the eastern U.S. and Canada?
There are no active plate boundaries.
Explain where most of the world's volcanoes occur and why.
They occur in the ring of fire and that is the location of most of the Earth's subduction zones.
Describe each type of volcano in the list below (how does it form and what does it look like), what is the viscosity of the magma and what volcanic rock type is associated with it?
Shield volcano
Composite volcano
Cinder cone
Volcanic dome
Composite volcano- "stratovolcano" volcano built up by many layers (strata) of hardened lava, tephra, pumice and ash. very pointy at the top traditional triangle shape, high amount of viscosity, considered the most dangerous type of volcano, and Andesite
Give an example of a stable and an unstable isotope.
stable- Pa-231 unstable- Promethium 238
What are unstable isotopes used for in Geology?
It's used to date ice cores and track the source of melts in igneous rocks. (dating)
What information comes from stable Oxygen isotopes (see p. 30)?
it has allowed scientist to identify climate change during relatively recent geologic time determining the temp of ocean waters because we can't sample past oceans we use fossil shells to determine the oxygen isotope ratios at the time when the organism w
If plutons form inside the earth, what has to happen before we can see them at the surface? (see p. 67-68)
erosion wears away overlying rock
plate tectonics is a result of earth's internal heat engine, powered by
heat flowing from earth's interior outward
volcanic island arcs are associated with
ocean-ocean convergence
erosion is a result of earth's external heat engine, powered by
gravity, the sun
The age of Earth is estimated to be approximately
4,550,000,000
A Substance that cannot be broken down into other substances by ordinary chemical methods is a(n)
element
the subatomic particles that contribute a single negative charge is the
electron
atoms of an element containing different numbers of nutrons the same number of protons are called
isotopes
the bonding between Cl and Na is halite is
ionic
which is not true of a single silicon-oxygen tetrahedron
it has four silicon atoms
which of these common minerals is not a silicate
gypsum
which of these minerals commonly forms as an evaporate from evaporating water?
halite
which of the following is an example of a shield volcano
mauna loa, hawaii
volcanic eruptions can affect the climate because
volcanic dust and gas can reduce the amount of solar radiation that penetrates the atmosphere
the gas mostly released during a volcanic eruption is
water vapor
is a rock composted of frothly volcanic glassy
pumice
a lava flow with ropy or billowy surface is called
pahoehoe
which of these is not a type of pyroclastic material
a'a
which of these is not a major type of volcano
spatter cone
an example of a composite volcano is
fujiyama, mount rainier
which volcano is not usually made of basalt
composite cone
the major difference between intrusive igneous rocks and extrusive igneous rocks is
where they solitify
which is not an intrusive igneous rock
rhyolite
flux melting occurs
water is added to the asthenosphere
The continuous branch of Bowen's reaction series contains the mineral
plagioclase
the discontinuous branch of Bowen's reaction series contains the mineral
pyroxene, amphibole, olivine
A change in magma composition due to melting of surrounding country rock is called
assimilation
by definition stocks differ from batholiths in
size
A discordant shallow intrusive structure is called a
dike
The most common igneous rock of the continents is
granite