GEOL Quiz #1

Understand the characteristics that define a mineral

Understand the characteristics that define a mineral

• naturally occurring

• Inorganic (not consisting of or deriving from living matter)

• Crystalline solids

• have a distinct chemical composition

• Have a unique set of physical properties

Know how minerals are classified

minerals are classified based on their composition

Know the basic composition of the earth

oxygen and silicon account for approximately 75% of the crust of the earth

Understand how rocks are named

the type and name of the is determined by two criterion texture and composition

Texture

how the minerals, rock fragments or fossils are put together

composition

minerals, rock fragments, fossils

Intrusive Igneous rock

• Crystallize from molten materials

• Coarse-grained interlocking texture which this texture generally results in a rock that is resistant to erosion

• Found within the crust

Interlocking texture

the minerals in the rock are inter-grown with one another

Coarse grained

the components of the rock are large enough to see with an unaided eye

Extrusive igneous rock

• crystallize from molten materials

• fine-grained interlock texture

• Found on the surface

Fine-grained

components in the rock are too small to be distinguished with an unaided eye

Detrital or clastic sedimentary rock

• formed from compaction and cementation of fragments of per-existing rocks and / or minerals

• on the surface

Chemical sedimentary rock

• formed from mineral that precipitate out of water

• On the surface

Metamorphic rock

• form from re-crystallization of per-existing rocks due to elevated what and / or pressure

• formed within the crust

Understand the information that can be obtained from the study of the different rock types

• 92% of the earth’s crust is igneous or metamorphic rock, but most of the earth’s surface (75%) is sedimentary rock rock

Understand the techniques used to study the earth’s interior

• Seismic waves and wave profiles (p and s waves)

Seismic

• shock waves generated by earthquakes and explosions - to reveal the structure of the interior of the planet

P-waves (also called compression or primary waves)

• the first waves to arrive at a seismograph, they can move through solid, liquid or gas

S-waves (also called shear or secondary waves)

• They are the secondary seismic wave to be felt or recorded during an earthquake

Inner core

• Iron inner core

• solid

• mostly composed of Fe, Ni

Outer core

• Iron outer core

• Liquid

• Mostly composed of Fe, Ni

Mantel

• Composed of Fe, Mg silicates (ultramafic)

• Solid - except for one layer known as the asthenosphere

Crust

• Composed of mafic rock (silicate mineral or igneous rock)

  • two different types: oceanic and continental

• Solid

Lithosphere

• composed of rocks and minerals OR the crust and lithosphere mantle (the upper most part of the mantle which is solid)

• Solid

Astenosphere

• composed of peridotitem a rock containing mostly the minerals olivine and pyroxene

• it is solid that can behave like a liquid it exhibits ductile behavior - it is capable of being deformed without losing its strength

The terminology for the composition of silicate rocks on the earth

• (everything except the core, which contains very little silicon or oxygen) is based on the amount of silica and (in order from high to low silica) includes felsic, intermediate, mafic and ultramafic

Describe the theory of plate tectonics

• geologic processes created due to movement of earth’s Lithosphere plates ( the tectonics plates move which causes the earth to change)

Continental rift

• Processes: separation of two continents into two tectonic plates takes place

• Geographic features

  • Earthquakes and volcanism

  • Long mountain ranges separated by broad valleys (basins)

    • Pull apart

      • Example: East African Rift

Rift

• linear zone where the earth’s lithosphere is being pulled apart, commonly a valley is formed and the feature is a result of extensional tectonics

Oceanic rift

• Processes: New oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates

• Geographic features

  • Volcanism

    • Pull apart

      • Example: Mid-Atlantic ridge

Convergent with subduction

• Processes: is an area on earth where two or more lithosphere plates collide, one plate (oceanic crust) eventually slides beneath the other called subduction (one plate goes underneath the another plate)

• Geographic features

  • Deep trenches and earthquakes

Convergent without subduction

• Processes: Collision of two plates

• Geographic features

  • Very high mountain belts

    • Example: Himalayas

transform

• Processes: plates slide past one another (nothing is created nor destroyed)

• Geographic features

  • masses of rock displaced tens to hundreds of miles, shallow earthquakes, and a landscape consisting of long ridges separate by narrow valleys

    • Example: California’s San Andreas fault

Example: at a divergent (rifting) location the lithosphere…

• Is thinned, creating a valley and mafic magma is formed from melting of the mantle creating mafic volcanoes

Example: at a convergent plate boundary where subduction of oceanic lithosphere occurs

• a deep ocean trench is formed. Magma is generated from melting of the mantle and results in the formation of intermediate composition volcanic mountain ranges. additionally, non-volcanic mountains are formed form sediment / ocean floor rocks being “scraped” off of the sub-ducting plate (accretion)

Know when and how the geological time scale was developed

• the geologic time scale was developed in the 19th century using relative dating techniques

Relative dating techniques

• the science of determining the relative order of past events without necessarily determining their absolute age

Be familiar with the geologic time scale and be able to answer questions

• Bottom is older then the top

Relative age dating methods

• Principle of uniformitarianism

• Principle of original horizonality

• Principle of superposition

• Cross cutting relationships

• Inclusions

• Principle of fossil succession

Principle of uniformitarianism

• Meaning “the present is the key to the past”

Prinicple of original horizonality

• sedimentary rock are deposited as horizontal layers

  • if sedimentary rocks are folded (or faulted) the deformation occurred after deposition

Principle of superposition

• in an undisturbed sequence, each layer of rock is younger than the layer below and older than the layer above (bottom is older then the top layer)

Cross cutting relationships

• igneous intrusions and faults are younger than the rocks that they intrude or break

  • —/— the / line is younger than the —line. The / line cut the —

Inclusions

• A piece of rock is completely enclosed by a different rock: the piece (inclusion) is older

Principle of fossil succession

• Fossils may also be used to obtain an absolute age of rock

  • Absolute age of rock

    • assigning actual dates (in years before the present) to rocks or geological events

What is an unconformity (be able to recognize it in a diagram)

• is a surface between two rocks units of different ages and represents a period of erosion

  • Unconformities are classified and recognized based upon the rock type and relationship of the geologic units

Describe the technique of radiometric dating

• parents material: original unstable isotope

• daughter product: secondary stable isotope

• half-life: amount of time it takes for one-half of the parent material to decay to the daughter product

What are the limitations and assumptions inherent in radiometric methods of dating rocks

• Decay rate is constant

• is it a closed system (no material lost of gained)

• all daughter product is a result of radioactive decay of parent materials

• our analytical methods are accurate

Silica

• silicon + oxygen

Clastic texture

• the components (minerals, rock fragments or fossils) are cemented together. the commenting material is generally quartz or calcite that has been deposited from ground water

Foliation

• the alignment of minerals

Ultramafic

• Dark color, very high density

Mafic

• Dark color minerals (and rocks), high density

Intermediate

• Dark and light colored minerals (and rocks), medium density

Felsic

• light color minerals (and rocks), low density

Mid Ocean ridge

• Linear feature where two lithospheric plates are being pulled apart. it consists of mafic volcanic rocks and is uplifted relative to the rest of the ocean basins

Deep ocean trench

• where the land splits in the ocean

Volcanic arc

• a belt of volcanoes formed above a subducting oceanic tectonic plate

Collisional mountains

• range formed

Accretion / accretionary wedge

• the purple stuff

Techniques radioactivity

• the release of energy from the decay of the nuclei of certain kinds of atoms and isotopes

Example questions: What property of igneouse rocks affects the size of the crystals

• The rate of cooling

Example questions: A rock that consists of pieces glued together would be said to have a

• Clastic texture

If two oceanic tectonic plates converge, which of the following features or processes is likely to result

• a deep ocean trench

Know how national parks are created in the US

• The creation of a national park requires an act of congress

• The national park service was created by the US congress

Understand the administration of public lands

• President

  • Department of Interior

    • Bureau of land management

    • Fish and wildlife

    • Bureau of Indian affairs

    • National park service

      • National parks

      • Other park areas

  • Department of agriculture

    • US forest service

  • DOD and DOE