Geo Lab midterm

There are 31.1 grams (g) in 1 troy ounce (ozt). How many ozt of gold are extracted from 1 short ton of average Nevada ore

0.103 ozt

Use your measurements from the Part B instructions to calculate the annual rate of spreading at placemark A. Assume that the rift began opening 20 million years ago. (Answer to the nearest centimeter per year.)

0.98 centimeters/year

Match each key term to the appropriate description. Be sure to complete each sentence before submitting your answer. All terms will be used, and terms may be reused.

1. A mid-ocean ridge occurs at a divergent boundary. 2. The lithosphere is destroyed at convergent boundaries. 3. A trench indicates the location of a convergent boundary. 4. Lithosphere is neither created nor destroyed at transform boundaries. 5. Subduction occurs neither at transform boundaries nor at divergent boundaries. 6. New lithosphere is created at divergent boundaries. 7. Transform boundaries often cut across and offset segments of divergent boundaries.

Use your measurements from the Part C instructions and assume that the rift began opening 20 million years ago. What is the spreading rate for the region of placemark B?

1.5 centimeters/year

Determine how much a block sinks in water. The density of the block is 0.8 g/cm3, its mass is 2 g, and the volume is 8 cm3. The density of the water is 1.0 g/cm3. How much of the block's mass is below the water surface?

1.6g

What was the rate (in cm/yr) and direction of Pacific Plate motion relative to the Hawaiian hotspot as it was developing the 2,300 km long Emperor Seamount Chain from 65 Myr to 42 Myr?

10 cm/yr to the north

Part complete The figure below shows the latitude and longitude time-series for a GPS site located near North Little Rock, Arkansas (a photo of the site is also below). What is the magnitude and direction of motion at this site?

13.64 mm/yr to the southwest

The GPS station BURI is moving at a rate of

13.69 mm/yr

What is the average speed at which BNA and BAF moved away from the ridge at A during the past 67.7 Myr, expressed in cm/yr? _____________

2 cm/yr

A geologist is studying a rock that is half a meter long, 325 centimeters wide, and 150 centimeters tall. What is the volume of this rock?

2,437,500 cm3

The figure below shows the latitude and longitude time-series for a GPS site located in Genova, Italy (a photo of the site is also below). What is the magnitude and direction of motion at this site?

26.23 mm/yr to the northeast

Using Lo'ihi Seamount as the current location of the Hawaiian hotspot, what was the rate and direction of Pacific Plate motion relative to the Hawaiian hotspot from 0.8 Myr to today?

28 cm/yr to the north-northwest

What has been the average rate and direction of sea-floor spreading in cm/yr west of the Juan de Fuca Ridge between points A and B and east of the Juan de Fuca Ridge between points B and C? (Note that the distance between A and B is about 250 km, while the distance between B and C is about 240 km

3 cm/yr

How many directions of cleavage does this sample have, and what angle do they make with one another?

3 directions not at 90°

The GPS station MALI is moving at a rate of

31.19 mm/yr

Based on the map, what was the average speed and direction of North American Plate motion at Yellowstone, relative to the hotspot, since 13.8 Myr?

4.3 cm/yr to the southwest

GPS data can be used to track the rate and direction of plate movement. If a GPS unit measures a latitude velocity of 28.2 mm/yr and a longitude velocity of 59 mm/yr, what is the velocity of plate motion?

65.4 mm/yr

GPS station HNLC on Oahu has the following component velocities relative to the NNR reference frame: moving north at 3.46 cm/yr and moving west at 6.28 cm/yr. Use the Pythagorean Theorem to find the current speed of the Pacific Plate at Oahu, relative to the NNR reference frame. What is your calculated velocity in cm/yr?

7.17 cm/yr

The GPS station HNLC is moving at a rate of

71.53 mm/yr

You need to determine the specific gravity of a sample. After putting the sample on a lab scale, you know it has a mass of 85 grams. Using a graduated cylinder, you know it has a volume of 9.5 mL. What is the specific gravity of the sample?

8.9

What was the rate (in cm/yr) and direction of Pacific Plate motion relative to the Hawaiian hotspot from 5.1 Myr to 0.8 Myr?

9 cm/yr to the northwest

Which of the labeled placemark pairs in the Pangaea folder represents locations that would have been adjacent or nearly adjacent when the super-continent was contiguous?

A

Please select all of the conditions that would increase the buoyancy of a crustal plate.

A glacier on the crustal plate melts Sediment is transported from the crustal plate to the ocean.

The interior layers of the Earth can be determined based on either chemical properties or physical properties. Which of the layers listed below would be an example of a layer of Earth defined by physical properties?

Asthenosphere

Which of the following scales is the smallest scale a geologist can work with?

Atomic

To determine the elevation of a point using Google Earth: Navigate to the location by entering coordinates or place name in the search bar. Zoom into the point. Hover your mouse over the point. Look at the box in the lower-left corner of the Google Earth application window. The elevation value is next to the "elev" label. Below are ranges of elevation. Select the range that includes the topographic relief between 36.465766°N, 118.550556°W and 36.510885°N, 119.735410°W.

Between 10,000 and 11,000 feet

Based on the information in the Bathymetry folder, at which placemark would you expect to find the oldest oceanic crust material?

C

Which mineral(s) might you be examining if you place some hydrochloric (HCl) acid on a sample and it fizzes? Choose all that apply.

Calcite Dolomite

Based on your work with lab specimens and the information available on pages 93-97 of your lab manual, which of the following characteristics would you use to differentiate between specimens of calcite and gypsum?

Calcite is harder than gypsum Calcite effervesces (fizzes) with dilute HCl, whereas gypsum does not.

Which of the following lab tools will be most useful in determining a mineral's streak?

Ceramic plate

What physical property of minerals describes how they will break along a plane of weakness in a crystal lattice?

Cleavage

What important element can be refined by grinding up chalcopyrite?

Copper

Based on the information in the Bathymetry folder, which of the following placemarks is located along a mid-ocean ridge?

D

What kind of tectonic boundary would be evidenced by down-dropped blocks of rock and shallow-focused earthquakes?

Divergent boundary

Based on your work with lab specimens and the information available on pages 93-97 of your lab manual, which of the following characteristics would you use to differentiate between specimens of calcite and dolomite?

Dolomite is harder than calcite.Calcite effervesces with direct application of HCl, whereas dolomite only effervesces with HCl when it is powdered.

Please rank the following steps of the process of clastic sedimentary rock formation from first to last. Assume you start the sequence with an exposure of rock on a hillside. Rank the processes below from first to last.

First Step erosion transportation deposition lithification

Based on your work with lab specimens and the information available on pages 93-97 of your lab manual, which of the following characteristics would you use to differentiate between specimens of galena and graphite?

Galena is cubic, whereas graphite is generally amorphous. Galena is harder than graphite

You need to determine the volume of a rock, but the rock in question has an irregular shape, so the standard volume equation will not work. Which of the following lab tools can be used to determine the volume of the rock?

Graduated cylinder

Based on the evidence found in Google Earth™, which of the following mountain ranges are most closely linked geologically to the Appalachian Mountains?

Grampian Mountains

Based on your work with lab specimens and the information available on pages 93-97 of your lab manual, which of the following characteristics would you use to differentiate between specimens of halite and quartz?

Halite has a salty taste, whereas quartz does not. Quartz is harder than halite.A quartz crystal is hexagonal in cross section, whereas a halite crystal is square in cross section.

Which one of the following statements is the best explanation for why the Expanding Earth Hypothesis was rejected using this logic and approach?

If the hypothesis were true, more crust would need to be created than destroyed. Since crust is being created and destroyed in equal amounts, the hypothesis must be rejected.

Which one of the following statements is the best explanation for why the Shrinking Earth Hypothesis was rejected?

If the hypothesis were true, more lithosphere needs to be destroyed than created. Since lithosphere is being created and destroyed in equal amounts, the hypothesis must be rejected.

Part complete Igneous, sedimentary, and metamorphic rocks all form in environments different from each other. As a result, each rock class is related only to one or more very specific origin(s). Please sort the origins below into the rock classes to which they belong. Drag the appropriate items into their respective bins. Each item may be used only once.

Igneous Origins extrusive intrusive Sedimentary Origins biochemical chemical detrital Metamorphic Origins parent rock

For this question, think about what you have learned regarding the formation of dikes and how these features are exposed at the surface today. Rank the following events in order from oldest to youngest in age. Rank from oldest to youngest.

Oldest Event Magma is injected far below Earth's surface, cutting through sedimentary country rocks. Magma crystallizes and a dike is formed. Sedimentary country rocks are eroded away. Humans build a tunnel and road through the resistant igneous rocks.

For this question, focus on the series of geologic events that led to the current expression that we see today. Arrange the following events in order of age. Rank from oldest to youngest.

Oldest Event Oldest Event Magma errupts explosively unto Earth surface. Volcanism ceases and magma crystallizes into rock. The flanks (sides) of the volcano and surrounding country rock start to erode away. The conduit is exposed at Earth's surface to form a volcanic neck. Youngest Event

Based on your work with lab specimens and the information available on pages 93-97 of your lab manual, which of the following characteristics would you use to differentiate between specimens of pyrite and gold?

Pyrite is harder than gold.Gold has a yellow streak, whereas pyrite has a dark gray streak.

Please sort the terms below into the categories Sedimentary Textures and Sedimentary Compositions according to which characteristic they describe. Drag the appropriate items into their respective bins. Each item may be used only once.

Sedimentary Texture poorly sorted well rounded sand silt Sedimentary Composition chemical biochemical detrital siliciclastic

Please rank the four lithospheric plates listed from slowest moving to quickest moving.

Slowest Moving Plate Antarctic Plate Eurasian Plate African Plate Pacific Plate Quickest Moving Plate

Using Moh's hardness information provided on pages 93-97, please rank the minerals below from softest to hardest. Rank the minerals from softest to hardest.

Softest Mineral graphite gypsum calcite dolomite hornblende olivine Hardest Mineral

Indicate which statements below are correct by navigating to the coordinates using Google Earth

The location at 28.510920°N, 14.013161°W appears to have a dry climate. The point at 8.5093°S, 179.1161°E is in the center of a ring-shaped island.

Please examine these photographs of the mineral quartz, shown on the left, and the rock granite, shown on the right. Comparing this mineral to this rock, select all of the ways in which they differ.

The mineral is mainly one color, whereas the rock consists of several different colors. The mineral is translucent, whereas the rock is opaque. The mineral as a whole is a three-dimensional geometric crystal, whereas the rock as a whole lacks this geometry.

Notice that the magnitude (and direction) of the predicted plate motion at each GPS site is slightly different than that which you calculated for the GPS site velocities in Part A & B. What is the most likely reason for the difference between the observed velocities of the sites from the GPS time-series and those predicted by the MORVEL2010 model plate motions?

The observed motion from GPS includes both the motion of the plates as well as a component of motion related to the deformation of the part of the plates where the GPS stations are located.

In many global maps of the tectonic plates like the portion shown above, lines with triangular teeth between two plates represent convergent boundaries. The example of such a boundary shown above is between the oceanic Nazca Plate and the continental South American Plate. On which of the two plates are the triangles located?

The overlying plate

Select the correct statements below about an iceberg with a density of 0.917 g/cm3 that is submerged in ocean water with a density of 1.025 g/cm3.

The percentage of the iceberg underwater will stay the same if a small portion of the top of the iceberg melts. An iceberg that is 65 m high will have between 56 and 58 m of that height submerged

A mineral scratches a knife blade but does not scratch a streak plate. What is the hardness of the mineral?

between 5.5 and 7

Which of the following environments would produce igneous rocks?

convergent boundaries divergent boundaries hot spots

A pattern of earthquakes that are shallow at the plate boundary and get progressively deeper are evidence of a _____ plate boundary. An example of this is found in __________.

convergent; Western South America

Of the listed biochemical sedimentary rocks, which rocks fizz with the direct application of dilute HCl? Please consult Figure 6.9 on page 164 of the lab manual if you need assistance. Select all that apply.

coquina chalk fossilliferous limestone micrite

Which of the textures below describe chemical sedimentary rocks? Select all that apply.

crystalline microcrystalline

Which of the rock types below could serve as a parent rock of eclogite?

gabbro basalt

Which of the following evidence does NOT support plate tectonics?

presence of magnetic field

Complete the following sentence: Isostasy of Earth's crustal plates exists because

the mantle is solid with the ability to flow slowly.

Does the direction of the GPS velocity vector at HNLC generally match the direction of plate motion over the last 42 Myr as revealed by the Hawaiian Islands Hotspot track?

yes

The Red Sea presents a simple geometry of an elongate oceanic basin. Volcanic rocks along both shores of the Red Sea display similar ages of ~20 million years. Examine the shape of the shoreline of Red Sea. What type of tectonic environment is present at the Red Sea?

The Red Sea is a divergent plate boundary, where new rocks are being created at the center of the Red Sea as the Arabian peninsula and Africa are pulling apart.

Locations on Earth can be described using one of several coordinate systems. Match the coordinates below with the name of the coordinate system.

19°27'43"N, 155°35'45"W: degrees-minutes-seconds 51.3485°N, 125.2630°W decimal degrees 32 V, 394192 m E, 6833944 m N Universal Transverse Mercator (UTM) 53° 10.979'N, 107° 48.346'E degrees-decimal minutes

The GPS station NRIL is moving at a rate of

22.25 mm/yr

The textures of igneous rocks, sedimentary rocks, and metamorphic rocks are all described with different terminology. That is, you cannot describe the texture of a sedimentary rock with the terms used to describe textures of igneous rocks. Bearing this in mind, please sort the terms below pertaining to rock textures into the three rock classes. Igneous rocks have textures that are either comprised of interlocking crystals, or textures that resulted from the cooling of hot liquid material. Sedimentary rocks have textures that result from the transport and assembly of materials or from the precipitation of minerals. The textures of metamorphic rocks consist of mineral crystals that may or may not be aligned parallel to each other. Drag the appropriate items into their respective bins. Each item may be used only once.

Igneous Textures aphanitic phaneritic pegmatitic vesicular porphyritic Sedimentary Textures well-sorted/poorly-sorted grain sizes well-rounded/very angular Metamorphic Textures foliated nonfoliated

Sedimentary structures are helpful for reconstructing the environmental conditions under which the sediments were deposited prior to lithifying into rock. This is because sedimentary structures preserve the type and direction of forces that acted on the sediment during transport and deposition. Please organize the five sedimentary structures below based on the direction of water movement during sediment deposition. Figure 6.12 on pages 169 and 170 provides helpful information. Drag the appropriate items into their respective bins. Each item may be used only once.

No Horizontal Water Movement raindrops mudcracks One-Way Water Movement current ripples flutes Two-Way Water Movement wave ripples

You are visiting Key West, Florida. Which tectonic plate are you on, and what is the nearest adjacent plate?

North American Plate; Caribbean Plate

The continental and oceanic crust that cover Earth are not one in the same, but rather differ in composition, density, thickness, and coverage of Earth's surface. Below you will sort the specifics of these contrasts into the two types of crust.

Oceanic Crust: more dense, basaltic, generally thinner, covers 70.8% of the Earth's surface Continental Crust: less dense, generally thicker, granitic, covers 29.2% of the Earth's surface

Clastic sedimentary rocks are formed during a process called diagenesis. The process of diagenesis is similar for many sedimentary rock types. Here is the process described specially for the diagenesis of sand into sandstone. Imagine a large deposit of loose sand sediment along a shoreline. Over a great amount of time, the sand is compacted as more and more sand is piled on top. Greater depths increase heat and pressure, which cause the sand to cement together, and become sandstone. Over time, the material above the sandstone will be eroded, as will the sandstone. Sedimentary rocks that have clasts prone to falling off are said to be poorly cemented, while rocks with clasts firmly in place are well cemented. Sort the statements describing the clasts shown. Drag the appropriate items to their respective bins.

Statement describes the rock shown in this Gigapan The clasts of this rock are well cemented. The clasts within this rock show signs of abrasion. The clasts within this rock are older than the rock itself. Statement does NOT describe the rock shown in this Gigapan The clasts within this rock are all from the same rock type. The clasts within this rock are younger than the rock itself.