GEOL 101 Lab Final
True or False: Felsic minerals have a higher silica content than mafic minerals.
True
True or False: Flow direction can be interpreted from asymmetrical ripple marks.
True
True or False: In graded beds, the larger grains are at the bottom of the layer, and the smaller grains are at the top.
True
True or False: There are two types of crust: oceanic and continental. Oceanic crust is more dense and therefore able to be subducted.
True
True or False: Contact metamorphism occurs when rocks are exposed to an increase in heat, but no change in pressure
True. Rocks undergo elevated heat, but not pressure, in contact metamorphism.
Rocks that are very dark or greenish in color; nearly all of their mineral content is ferromagnesian (86-100%)
Ultramafic rocks
When a stream intersects contour lines on a topographic map, the contour lines point:
Uphill
Do seismic waves strengthen or weaken as they move away from the focus?
Weaken
What are the two main problems seismologists solve?
What is the Earth's structure & what is the source
Minerals are divided into chemical groups by the _____.
anion
If a mineral has a hardness of 4, it
can scratch a penny
Which of these properties is ambiguous?
color
Total relief
difference in elevation between the highest and lowest areas on a map
Local relief
difference in elevation between two areas being compared
A typical longitudinal profile of a stream:
illustrates that a stream's gradient is steeper near its headwaters than near its mouth.
The paleomagnetic record:
is preserved in strips of rock parallel to the mid-ocean ridge. is preserved in basalt layers on land. is symmetrical across the mid-ocean ridge. shows magnetic reversals over geologic time.
Which of the following is NOT part of the definition of a mineral?
liquid
**Know meter measurements**
10 mm = 1 cm 10 cm = 1 dm 10 dm = 1 m 1,000 m = 1 km 100cm = 1 m 100,000 cm = 1 km
What are the latitude and longitude coordinates for Captain Cook?
19°30'N, 155°50'W
Imagine that you have four maps that are all centered on the same location, but they all have different scales as follows: (a) 1:20,000 (b) 1:200 (c) 1:1,000 (d) 1:300,000 Which map would show the most detail?
1:200
The half-life of Uranium-235 is ~713 million years. A rock originally contained 24mg of U-235. The rock now contains only 3mg of U-235. About how old is the rock?
2.139 billion years
A paleontologist estimates that when a particular rock formed, it contained 36mg of the radioactive isotope potassium-40. The rock now contains 4.5mg of potassium-40. The half-life of potassium-40 is 1.3 billion years. About how old is the rock?
3.9 billion years
A copper ore body has a volume of 1,000,000 m3. The ore has an average density of 3000 kg/m3. If the grade of the deposit is 0.01%, what is the mass of the copper in the deposit?
300,000 kg
Determine the relative hardness for a mineral sample that scratches a glass plate and leaves a streak on the steak plate.
5.5 - 7
If a mineral scratches glass (H: 5.5), but does not scratch a streak plate (H: 7), what is its hardness range?
5.5 - 7
A half-life is the time it takes for _____ % of the parent isotopes to decay.
50
An ancient meteorite was found on Earth and geoscientists want to date it using Ar40 as the parent and this decays to K40 (t1/2 = 1.25 billion years). If there was originally 72mg of Ar40 and after careful analysis found there to be 2.25mg of Ar40 in the meteorite now, how old is the meteorite?
6.25 billion years old
Some sources say the average single-family home in the United States uses about 420 pounds of copper within the plumbing, appliances, building wire, and more. In the 21st century, an average copper grade ore might be ~0.6%. How many pounds of 0.6% grade copper ore needs to be mined in order to obtain 420 pounds of copper?
70,000 pounds of copper ore
If a nickel ore has a grade of 2%, it means there are 2 pounds of nickel for every 100 pounds of ore. It also means that there are 2 grams of nickel for every 100 grams of ore, etc., so long as the unit of comparison remains the same within the percentage calculation (pounds to pounds or grams to grams or ounces to ounces, etc.). Some sources say that the average single family home in the United States uses approximately 400 pounds of copper within the plumbing, appliances, building wire, and more. The average copper grade ore being mined today is ~0.5%. How many pounds of 0.5% grade copper ore needs to be mined in order to obtain 400 pounds of copper?
80,000 pounds of copper ore
Uranium-238 decays very slowly, with a half-life of 4.5 billion years. What percentage of a sample of Uranium-238 would remain after 281,250,000 years passed?
93.75%
What is an index fossil?
A fossil widely distributed around the Earth that lived for a very short time period
A poorly sorted sedimentary rock with angular clasts ranging in size from boulders to pebbles may be been deposited in which environment?
Alluvial fan
Which compositional class would a metamorphic rock comprised of mainly micas (biotite and muscovite) and garnets belong to?
Aluminous
An uncomformity that separates a younger, gentle dipping rock unit from older underlying rocks that are titled or deformed layered rock.
Angular uncomformity
Which of the following drainage basin types reflects the presence of rocks that are equally resistant to erosion?
Dendritic
Dendritic basin
Develop where surface materials are equally resistant to erosion. This may mean horizontal sedimentary or volcanic rocks; loose, unconsolidated sediment; or igneous and metamorphic areas where most rocks erode at the same rate
Law of Cross Cutting
Any feature that cuts across a rock or body of sediment must be younger than the rock or sediment it cuts across.
Law of Inclusions
Any piece of rock (clast) that has become included in another rock or body of sediment must be older than the rock or sediment into which it has been incorporated. Such a clast (usually a rock fragment, crystal, or fossil) is called an intrusion. The surrounding body of rock is called the matrix (or groundmass). An inclusion is older than its surrounding matrix.
Igneous rocks that are composed of crystals that are too small to see without a hand lens have this kind of texture
Aphanitic texture
Which set of ripples (asymmetrical or symmetrical) would you expect to find preserved in the rock along a river? Why?
Asymmetrical b/c will show direction of current
A contour interval is the
Difference in elevation between one contour line and the next.
An uncomformity wherein erosional contacts are parallel to the bedding planes of the upper and lower rock units.
Discomformity
Gradient
Dividing the relief between two points by the distance measured from the map. Expressed in feet per mile or meters per kilometer.
The area drained by a single stream is called
Drainage basin
True or False: A grain's size increases as it travels farther from its source.
False
True or False: A high-grade metamorphic rock looks very similar to its protolith.
False
True or False: All rivers and streams flow from north to south.
False
True or False: Contact metamorphism involves the application of differential stress, which causes foliation to occur in metamorphic rocks.
False
True or False: Contact metamorphism produces rocks with foliated texture.
False
True or False: Continental crust is created at mid ocean ridges.
False
True or False: Contour lines that cross a stream are V shaped. The "V" points to the area of lowest elevation, or in the downstream direction.
False
True or False: Every metamorphic rock has a foliated texture.
False
True or False: Fracture occurs when minerals break along zones of weakness and produce smooth, flat surfaces
False
True or False: If the relative age of two formations (with respect to one another) is known, then the numerical ages for each formation can be inferred.
False
True or False: Mafic is a term used to describe igneous rocks that are composed of primarily light colored minerals.
False
True or False: Mafic minerals are light colored silicate minerals.
False
True or False: Minerals always display their preferred crystal habit.
False
True or False: A stream either erodes vertically (by leveling its longitudinal profile to the elevation of its mouth) OR laterally (by broadening its valleys through meandering), but not both.
False It can erode both
How does erosion alter a piece of sediment over time, the further it is moved away from its source rock?
Farther away from source --> Smaller, more rounded, very well sorted grains
Name the different minerals you might expect to find in a felsic rock and the minerals you would expect to find in a mafic rock.
Felsic --> Quartz, K-feldspar Mafic --> Plagioclase, Augite, Olivine
Rocks that are very light in color; only a small amount of their mineral content is ferromagnesian? (0-15%)
Felsic rocks
What two textures are found in metamorphic rocks?
Foliated and non-foliated
Trellis basin
Form where ridges of resistant rock alternate with valleys underlain by weaker material.
Which method of correlation (lithologic or fossil) is more reliable for determining age equivalence among bodies of rock that are physically isolated by vast distances?
Fossil correlation
Principle of Fossil Succession
Fossil organisms originate, co-exist, or disappear from the geologic record in a definite sequential order recognized throughout the world, so any rock layer containing a group of fossils can be identified and dated in relation to other layers based on its fossils.
Match each phaneritic igneous rock type with its aphanitic equivalent.
Gabbro --> Basalt Granite --> Rhyolite Diorite --> Andesite
Rapid cooling of viscous magma may produce a volcanic rock that is smooth and shiny in appearance (ex. Obsidian or Pumice)
Glassy texture
How does grain shape change as a clast moves farther from its source?
Grain shape becomes more rounded
Clastic sedimentary rocks are primarily classified on the basis of _____, while chemical and biogenic sedimentary are classified according to _______.
Grain size; mineral composition
Explain why some minerals do not have a streak.
Harder than the streak plate
Is the threat of a lahar greater in Hawaii or Washington? Why?
Hawaii
The elevation of a river at its mouth
Base level
Which of the following depositional environments could have facilitate the formation of a quartz-rich sandstone with cross bedded layers?
Beach
Layers of sediment are called:
Beds
An earthquake occurs with an epicenter in the town of Shakesalot, Missouri, which is located in the interior of the North American Plate. Where might the hypocenter (focus) of this EQ plausibly be found?
Beneath Shakesalot.
The rule of Vs states that:
on a topographic map, contour lines that cross a stream form a V that points upstream
Which proportion of a radioactive isotope is expected to remain in an unaltered (unreacted) state after the passage of three half-lives?
one-eighth
A sedimentary rock with rich feldspar is a/an _______ rock and this rock is usually _____ to its original source; sandstone (with well sorted grain) forms a ____ (short/long) distance away from its original deposition; breccia (with angular shape grains) travels _____ (short/long) distance from its original location.
Immature Close Long Short
Law of Superposition
In an undisturbed sequence of strata or lava flows, the oldest layer is at the bottom of the sequence and the youngest is at the top.
Rectangular basin
Indicate zones of weakness (faults, fractures) perpendicular to one another
Rocks that contain more light-colored minerals than dark; nearly half of their mineral content may be ferromagnesian (16-45%).
Intermediate rocks
How would you tell if a rock is crystalline?
It contains interlocking crystals.
Harry Potter was walking through the Forbidden Forest when he came upon a magnificent mineral. In addition to the wizarding skills he learned at Hogwarts, he was also taught geology. However, he couldn't remember how to decipher between calcite, halite, and quartz. The mineral is slightly pink, displays 3 planes of cleavage, and the angles are not at 90 degrees. Can you determine what mineral Harry has found?
Calcite
If a rock fizzes with HCl, what mineral must it contain?
Calcite
The greater distance away from the earthquake focus a seismic station is, the (larger/smaller) the S-P time interval will be.
Larger
Law of Lateral Continuity
Lava flows and strata extend laterally in all directions until they thin to nothing (pinch out) or reach the edge of their basin of deposition.
Identify the physical layers of the Earth that facilitate plate tectonics.
Lithosphere and asthenosphere
Rocks that tend to be dark in color; a large portion of their mineral content is ferromagnesian (46-85%)
Mafic rocks
The difference between magma and lava is ____________.
Magma is found beneath the surface, whereas lava is found at the surface
What is the relationship between magma viscosity and eruption style?
Magmas with high viscosity have more explosive eruptions
What is the difference between magnitude and intensity?
Magnitude- the size of the earthquake at its source Intensity- severity of earthquake shaking
**Know how to calculate vertical exaggeration.**
Map over profile x-axis/y-axis Horizontal scale/Vertical scale
What luster do the minerals with high specific gravities display?
Metallic
What are the two main types of luster?
Metallic and nonmetallic
What happens to mineral grains when a rock undergoes differential stress?
Mineral grains will become flattened and elongated in one direction
The single property that can be used to identify any mineral is ________.
Multiple properties must be used to identify a mineral.
Which of the following is NOT a mineral?
petroleum (gold, diamond, and quartz are)
The place where two plates meet is referred to as a(n)-
plate boundary
Narrow river valleys typically contain:
Non-sinuous, fast moving streams
An uncomformity is a contact between two rocks layers in which the upper unit is much younger than the lower unit. Which of the following is an unconformity that separates younger sedimentary rock from older igneous or metamorphic rock?
Noncomformity
What is the approximate direction of motion of the overlying plate above the Hawaiian hot spot?
Northwest
Be able to compare Oceanic and Continental crust (differences in composition, density, thickness)
OCEANIC Thinner Denser Basalt CONTINENTAL Thicker Buoyant Gabbro
Annular basin
Occurs where there are concentric rings of alternating resistant and weak rocks - typically found in structures called domes and basins.
Why isn't continental crust subducted?
Oceanic crust is more denser and will always sink below.
At which type of plate boundary would you expect to find a volcanic island arc?
Oceanic-Oceanic subduction zone
How is the age of oceanic crust related to the bathymetry of the ocean floor? (Hint: is older crust near a ridge or a trench?)
Older crust near a trench Newer crust at a ridge
Stream gradient is calculated as:
relief / straight-line distance
Which body paves (P or S waves) have the greatest velocity?
P waves
The term used to describe the most recent super continent.
Pangaea
Which igneous rock texture is displayed in Granite?
Phaneritic
Igneous rocks that are composed of visible course-grained crystals.
Phaneritic texture
The large crystals found in the matrix or groundmass of rocks are called this
Phenocrysts
A magma that begins cooling intrusively, but then erupts and finishes cooling extrusively will display which texture?
Porphyritic
Which of the following igneous textures would represent a complex (or multi-stage) cooling history?
Porphyritic
When igneous rocks have TWO distinct crystal sizes; this is known as?
Porphyritic texture
4 tectonic zones of Earth
Ring of Fire, Pacific Ocean Mid-Atlantic Ridge, Atlantic Ocean Alpide Belt, Eurasia Madrid Area
Which of the following suggests that the rock layer has been deformed or overturned?
Ripple marks with the sharp points of the ripple pointing downward.
Which of the following best describes chalk?
Sedimentary, biogenic, contains CaCO3
Do most earthquakes have shallow, intermediate, or deep foci?
Shallow
A limestone would most likely form in a:
Shallow marine environment
What are hachures?
Short, dashed line at right angles to one side of the contour line; indicate a closed depression
Whether an eruption will primarily produce lava flows or pyroclastic debris is influenced by which of the following?
Silica composition of the source magma Proportion of volatiles in the source magma Viscosity of the source magma
Which class of minerals is the most abundant?
Silicates
Which of the following measurements associated with rivers is unitless?
Sinuosity Measures how much a stream meanders. Absolutely straight stream would have a sinuosity of 1 A stream with many meanders would a have high value of sinuosity Length of stream channel / Straight-line distance between the same points
Wide river valleys typically contain:
Sinuous, slow-moving streams
Place the aluminous metamorphic rocks in the proper order from lowest to highest grade:
Slate --> Phyllite --> Schist --> Gneiss
A seismogram is composed of signals from what other components?
Source, Earth, and the instrument
Volcanic island chain of the Hawaiian hot spot- What can you infer about the direction of the Pacific plate movement?
South to North
Radial basins
Streams flow either outward (centrifugal) from a high point (e.g. a volcano) or inward (centripetal) toward the center of a large basin.
The process by which one plate sinks back into the mantle below the other (overriding plate).
Subduction
In a undisturbed sequence of sedimentary rocks, younger layers overlay older layers, according to the principle of ____________.
Superposition
Do body waves or surface waves cause the most structural damage to buildings?
Surface waves
Law of Uncomformities
Surfaces called uncomformities represent gaps in the geologic record that formed wherever laters were not deposited for a time or else layers were removed by erosion.
Why can't you use only two seismic stations to get the distance of the epicenter?
The circles will intersect at two points, so there could be two possible epicenters.
What is the streak of a mineral?
The color of a mineral in powdered form
What is metamorphic grade?
The degree to which a rock has changed during metamorphism involving heat
Relief
The difference between the high and low areas of a map
Which of the following is true about index fossils?
They are fossils of organisms which lived during a short span of geologic time. They can be the remains of plants or animals. Tyrannosaurus rex could be an example of an index fossil.
If an igneous rock contains two different grain sizes, what does this say about its formation?
This rock cooled at variable rates during its formation.
What is the minimum number of seismic stations are needed to locate the epicenter of an EQ?
Three
Transgression vs. Regression
Transgression: Coatline migrates inland Position of beach moves inland Involves a relative rise in sea level Shale, limestone, sandstone, conglomerate (oldest) ^ Moves from coarse to fine (bottom up) Regression: Coastline migrates seaward Position of beach migrates seaward Involves a relative fall in sea level Conglomerate, sandstone, limestone, shale ^ Moves from fine to coarse (bottom up)
Choose the correct process of forming a clastic sedimentary rock from upstream to downstream direction:
Transportation --> weathering and erosion --> Deposition --> Lithification
True or False: A rock with large, angular fragments and lots of feldspar is classified as immature; a rock with smaller, rounded grains and not much feldspar is classified as mature.
True
True or False: Contour lines that are close together show a steep slope. Contour lines that are far apart represent a gentle slope.
True
True or False: Earth's lithosphere is broken into major (large) and minor (small) tectonically active plates.
True
What is the major difference between cleavage/fracture and crystal habit?
Cleavage/fracture is a result of breaking the mineral; internal Crystal habit results from how it forms; external
There are two physical properties of minerals that both result in smooth, flat surfaces with specific angles between them. The first property is the result of how the mineral forms; the second is the result of breaking a sample of the mineral. These properties are called
Crystal habit and cleavage
Sedimentary rocks that are formed from fragments of previously existing rocks are called:
Clastic
Areas of equal elevation are connected by _____ lines on a topographic map.
Contour
Match each of the following terms with the correct description below. (1)contour line (2)topography (3)relief (4)elevation
Contour line- line connecting points of equal elevation on a map Topography- Size and shape of Earth's surface features Relief- Difference between the highest and lowest elevations Elevation- Height above sea level of land or an object
At which type of plate boundary are most intermediate and deep focus earthquakes occurring?
Convergent subduction boundaries
Which of the following is necessary for a fossil to be an index fossil?
Existed for a short period of time Found in many areas on Earth, but in a limited thickness of rock Unique and easy to identify
Identify 1 cause of earthquakes not related to plate tectonics.
Explosions underground
Explain the relationship between igneous rock formation and grain size.
Extrusive, cooled quickly = Aphanitic Intrusive, cooled slowly = Phaneritic
Agents of metamorphism:
Heat Pressure Hydrothermal fluids
What are the agents of metamorphism?
Heat, pressure, hydrothermal fluids
What is an easy way to determine a mineral's specific gravity in the lab?
Hefting the mineral
What is the relationship between viscosity and the eruption style of the volcano?
Higher viscosity, the more explosive the eruption
Drainage divide
Highlands which separate drainage basins
The _______ is where the seismic waves originate inside the Earth, while the _________ is on the surface and is the site of greatest ground motion and damage.
Hypocenter; epicenter
Under what circumstances a does quartz crystal display a crystal habit?
Ideal, unimpeded growth conditions. TIME and SPACE.
Why can't you determine the direction to the epicenter using data from 1 seismometer?
If there is information from only one station, the epicenter of the earthquake could be at any point on that circle.
Processes and terms of the rock cycle.
Igneous Rock Weathering and Erosion Compacting and Cementing Sedimentary Rock Heat and Pressure Metamorphic Rock Melting -- > Magma Cooling Igneous Rock
Would you expect quartz or augite to be more resistant to weathering? Why?
Quartz more resistant to weathering - Bowen's Reaction Series; Felsic minerals are more stable bc they form at lower pressure and temperature conditions - i.e. conditions closer to those found on Earth's surface.
Match the different sedimentary rocks with their depositional environments.
Quartzose sandstone: Desert, beach Asymmetrical ripple bedded Conglomerate: Glacial Chert: Deep marine Fossiliferous limestone: Shallow marine, coral reef Breccia: Alluvial fan, river or lake
Explain why relative hardness is expressed as a range.
Relative to other materials; hardness isn't exact
Which lava will have a higher viscosity, basaltic or rhyolitic?
Rhyolitic
For the Richter magnitude, what is the relationship between magnitude, wave amplitude and distance from the epicenter?
Richter magnitude scale- size of the earthquake at its source; quantitative
As sediments are transported farther from their source, ____ is likely to increase:
Roundedness and Sorting
What is the cause of most earthquakes?
Rupturing at fault lines
What information must you have to determine the location of an earthquake?
S-P time interval Data from at least 3 seismic stations
Compare and contrast SHALE and LIMESTONE. Include grain size & packing information as well as a list of possible depositional environments.
SHALE Clastic Very fine-grained Breaks into parallel planes Can contain fossils Deep marine environment LIMESTONE Biogenic/chemical (biochemical) Calcite Contains fossils (fossiliferous limestone) Shallow marine environment
What is erosion?
The grinding away and removal of Earth's surface by water, wind or ice
A mineral's cleavage is described by
The number of cleavage planes ad the angles between those planes
A mineral's crystal habit is
The preferred crystal shape that forms when a mineral grows unimpeded by other grains
Wind-deposited sediment is usually _____-sorted.
Very well
Which igneous texture is displayed in Vesicular basalt?
Vesicular/Porous
How is the distribution of volcanoes and earthquakes related to plate tectonic boundaries?
Volcanoes, volcanic islands arcs & volcanic arcs: Subduction Earthquakes: transform boundaries
Continental divide
separates streams that flow into the Atlantic Ocean from those that flow to the Pacific The Appalachian Mountains are the divide separating the Gulf of Mexico and direct Atlantic Ocean drainage The Rocky Mountains separate Gulf of Mexico and Pacific drainage
You are looking at an outcrop and notice three rock layers in this order (from bottom to top): shale, limestone, sandstone. Which unit is the oldest, and which geologic principle helped you determine the age?
shale; principle of superposition