Geometry Exam 1

Hypotheses are always testable? A. True B. False

A

Which of the following is not a characteristic of a hypothesis? indisputable accounts for existing data testable predicts future behavior or data

indisputable

Which of the following is not a characteristic of a hypothesis? predicts future behavior or data accounts for existing data indisputable testable

indisputable

What type of minerals dissolves most easily in water?

ionically bonded minerals

What Are the Most Important Minerals?

-Silicates (most abundant and common, ~92-95% on continental crust, SiO4

Geochemical studies of rocks show that Earth is approximately ________ years old. 500 million 30 billion 4.5 billion 6 thousand

4.5 billion

Using the principle of Uniformitarianism, which makes the most sense? A crater from 4 million years ago is similar to one from an impact last year; the ancient crater probably wasn't caused by an impact however. A crater from 4 million years ago is similar to one from an impact last year; the ancient crater was probably also caused by an impact. A crater from 4 million years ago is similar to one from an impact last year; the ancient crater must not be as ancient as scientists thought. A crater from 4 million years ago is similar to one from an impact last year; the new crater must be a lot older than scientists thought.

A crater from 4 million years ago is similar to one from an impact last year; the ancient crater was probably also caused by an impact.

What's a rock?

A rock is defined as consisting of 1 or more minerals. There are some exceptions to the definition of a "rock." For example, geologists consider obsidian to be a rock. This a very quickly cooled glass that is formed naturally from volcanic processes. Obsidian is a glass with no specific composition or components with ordered internal structures, i.e., it is not composed of minerals. Another is Coal, which is formed naturally, and organic.

How can you tell the difference between plutonic and volcanic igneous rocks?

A volcanic rock is fine-grained; a plutonic rock is coarse-grained.

Decompression melting occurs because Decreasing viscosity near the surface causes pressure to decrease Answer Lower pressure results in a lower melt temperature Increasing temperature near the surface causes pressure to decrease Lower pressure results in a higher melt temperature

Answer Lower pressure results in a lower melt temperature When hot mantle rises, it will reach a point at which the pressure of the overlying crust and mantle is lowered enough that the proper combination of pressure and temperature exists and partial melting occurs. Review Section 4.6.

Subduction zones occur at a convergent boundary. neither a divergent, convergent nor transform boundary. a transform boundary. a divergent boundary.

At divergent plate boundaries, plate edges stretch and separate, new seafloor forms here. At convergent plate boundaries, plates collide nearly head on into one another. Where the plates converge, one plunges into the deeper mantle in a process called subduction, while the over-riding plate experiences volcanic activity and buckling that uplifts tall mountain ranges. So, divergent plates move away, while convergent plates move towards each other. Divergent plates stay at the "surface" while one of the convergent plates plunges at subduction zones. Divergent boundaries create crust, while convergent boundaries destroy crust.

Where does most mountain-building activity actually occur on Earth? Anywhere on Earth where the necessary forces are evident. In the inner mantle, where force causes pressure to build up. Mountain pressures that build up end up forming mountains in the middle of the tectonic plates. At tectonic plate boundaries.

At tectonic plate boundaries.

Where does most mountain-building activity actually occur on Earth? Mountain pressures that build up end up forming mountains in the middle of the tectonic plates. At tectonic plate boundaries. Anywhere on Earth where the necessary forces are evident. In the inner mantle, where force causes pressure to build up.

At tectonic plate boundaries.

2.3 How do Elements Combine to Make Minerals?

Bonding: From chemistry, we know that elements are combined, or bonded, to form compounds. Examples are H2O, and SiO2. The process whereby atoms are joined to other atoms is called Bonding. When atoms of two or more different elements are bonded, the resulting substance is a compound.

Which of the following statements is false about decompression melting?

C is false. Decompression means a drop in pressure, not an increase in pressure. If you do increase pressure, you do need increasing temperatures to melt rock - but this is not the case for decompression melting.

Can rocks be classified according to the processes that form them?

Classification is an important part of natural science. Scientists commonly group features or phenomena according to similarities in order to seek explanations for their origins. Descriptive classifications group items of similar appearance. Genetic classifications group features or phenomena by noting similarities in the processes that cause or create them.

How does convection cause the motion of plates that drives plate tectonics? Radiation of heat causes the plates to move, which in turn causes convection Convection blows the plates around the earth. Cold, dense lithosphere sinks, while hot, low-density mantle rises to the surface at hot spots Refraction of heat from the sun heats the plates, causing convection and the motion of the plates.

Cold, dense lithosphere sinks, while hot, low-density mantle rises to the surface at hot spots Conduction, is the transfer of heat from a hot object to a cold object, like your warm feet to cold tile. There is no transfer of the heat with mass, but a transfer of heat from one mass to another during conduction. Please review Figure 1.14 for the difference between conduction, convection and radiation. With plate tectonics, subducting slabs is the cold dense plate sinking while warm rock rises to fill in at divergent plate boundaries and hot spots.

Which statement about the melting temperature of rocks is incorrect?

Dry rocks melt at a lower temperature when the pressure is higher.

How does bonding affect the hardness of a crystal?

Covalently bonded crystals are harder than ionically bonded crystals.

Which of the following statements is false: Wet melting can produce volcanoes The water for wet melting can be delivered from the metamorphism of the subducting slab Wet melting occurs at subduction zones During wet melting, the subducting slab gets so hot it melts.

During wet melting, the subducting slab gets so hot it melts.

How does the concept of work apply to Earth?

Energy is the measure of the ability to do work.

Which of the following statements is true about the melting of minerals? Minerals in a rock will all melt at the same time when the right temperature is reached. Experiments show that rocks melt at lower temperatures when there is water present. All solid minerals transform into a liquid at the same temperature. Water does not influence the melting temperature of minerals.

Experiments show that rocks melt at lower temperatures when there is water present. Minerals melt at different temperatures, which are influenced by the pressure, and water content. When there is water or water-bearing minerals in the rock, it does not take as much heat to melt the rock.

A scientist must always follow exactly the same sequence of steps when testing a hypothesis, no matter what the hypothesis states. True False

F

Color is always a reliable property for identifying a mineral.

False

Evaluate the following statement: Chemical weathering causes rocks to disintegrate into smaller rocks or into even smaller grains.

False

It is appropriate to criticize a scientific theory by saying "it's only a theory" because it is a tentative explanation that accounts for the existing data. True False

False A theory is a systematic, broad-scope explanation consisting of one or more hypotheses which have been, or can be tested and which provide predictions that permit verification or rejection. A hypothesis is an untested explanation of incomplete scope, from which there may or may not emerge verifiable predications.

All major rock forming minerals are silicates.

False: Review Section 2.7. There are many non-silicate mineral groups also found on Earth. Examples include carbonates, native metals, sulfides, etc.

Cleavage is:

Flat, smooth planes along which a mineral breaks

4.9 How are volcanoes hazardous?

Geologists relate the hazardous nature of eruptions (lava flows, pyroclastic flows, distant fallout of volcanic ash) to the composition of the erupted material. The most deadly and destructive volcanic phenomena are fast moving, far traveling pyroclastic flows and lahars.

How Do We Know? Atomic Structure of Minerals

Geologists use transmission electron microscopes (TEM) to visualize arrangements of atoms inside minerals. TEM uses magnets to focus streams of tiny electrons through a small part of a mineral sample. Some electrons pass through the sample without encountering any obstacles. Other electrons bounce off atoms comprising the mineral. A detector beneath the sample records the arrival of electrons that passed through unhindered, and reveals electron paths that encountered atomic obstacles. Mineralogists use data from detector to produce images magnified up to 10 million times, and resolve features less than one millionth of a millimeter across. This very high level of magnification is sufficient to see the fuzzy outlines of most atoms. TEM images, made by firing electrons into a mineral sample, show the orderly internal arrangement of atoms unique to each mineral.

Graphite is a mineral but sugar is not. Why is this so?

Graphite is inorganic but sugar is organic.

What kinds of energy are there?

Heat represents the most important form of energy transfer for geological processes. Heat from the Sun fuels Earth-surface processes, like blowing wind, ocean waves, and the evaporation and precipitation of water. Natural radioactivity produces heat inside Earth's interior. This energy source is sufficient to power the work done by plate tectonics.

How and why do rocks melt?

If the temperature of a rock is raised high enough the rock will begin to melt. Every mineral has a measurable melting temperature that varies with pressure, which equates to depth below the surface and the weight (pressure) of overlying rock. Because rocks contain many different minerals and each mineral has its own melting point, we cannot refer to a single, specific melting temperature for the rock. Rather, the rock melts gradually over a range of temperatures as the melting points of the component minerals are reached. If the temperature does not exceed the melting point for all of the constituent minerals we say that the rock has only been partially melted. Generally speaking, minerals with greater silica content have lower melting temperatures than those with lower silica content. Therefore, when a rock only partially melts, the resulting magma is more silica-rich than the original rock. Make sure to review Figure 4.16. What is the geothermal gradient?

4.1 What are igneous processes?

Igneous processes involve the melting of rock to form magma and its subsequent solidification into new rock. Igneous products form where magma crystallizes below Earth's surface or erupts as lava and other materials onto Earth's surface.

How are igneous rocks classified?

Igneous rocks are named on the basis of composition (minerals present) and texture (size of mineral grains). Texture - The size of crystals in the rock is determined by a variety of factors of which cooling rate is generally most important. Phaneritic - Aphanitic - Composition - With increasing silica content magmas and their resulting rocks range from ultramafic, mafic, intermediate to felsic in composition. These terms reveal that magmas lower in silica are relatively richer in magnesium and iron. Likewise, those with higher silica are relatively enriched in the components of feldspar, especially aluminum, potassium, and sodium. Classification - pyroclastics - This approach of combining composition and texture is not adequate for the pyroclastic materials erupted from volcanoes. Because all of them are characteristically glassy, the most useful distinguishing feature is the size of the fragments, rather than the size or presence of minerals within the fragments.

Where do igneous rocks appear in the landscape?

Igneous rocks can be divided into two general categories based on where they formed. Volcanic (extrusive; includes pyroclastics): Volcanic rocks include lava flows, pyroclastic-fall deposits, and pyroclastic-flow deposits. Different magma compositions and types of eruptions, and varying proportions of lava flows to pyroclastic deposits determine the sizes and shapes of volcanoes. Plutonic (intrusive): When magma solidifies before reaching the surface, it is called plutonic rock. Plutonic rock bodies, sometimes called plutons, exist in varying shapes and sizes. These rocks are revealed at the surface only after the rock that originally covered them has been eroded (at Yosemite, for example). lutonic Rocks in the Landscape - Plutonic rocks are seen at the surface only because erosion has removed the rocks that were present above where the magma solidified. There are a number of landforms resulting from the various sizes and shapes of the original igneous intrusions. Dikes Sills Stocks and Batholiths Volcanic necks Volcanic Rocks in the Landscape - Lava Flows Pyroclastic deposits - These take on a variety of appearances, as well, related to whether the explosively-generated fragments fall from the sky or flow down the slopes of the volcanoes. Types of volcanoes - Cinder cone - Shield volcanoes - Composite volcanoes - Lava domes/ Dome Complexes -

What Determines the Physical Properties of Minerals?

In other words, the properties reflect the elements of which they are composed up and the way the elements are arranged within their structures. Many physical properties are remarkably constant for a given mineral species, but some, especially color, may vary.

What is a scientific theory?

In scientific usage, a theory is a coherent explanation for one or several related natural phenomena that is supported by a large body of objective evidence.

Convection occurs in which of the following: Turning on a burner under a pot Inside Earth Ice in a glass of water Putting your warm hand on your cold face during a winter's morning

Inside Earth the transfer of heat WITH mass (like rising soup, or rising warm air). Conduction, is the transfer of heat from a hot object to a cold object, like your warm feet to cold tile. There is no transfer of the heat with mass, but a transfer of heat from one mass to another during conduction. Please review Figure 1.14 for the difference between conduction and convection. These processes will play a significant roll in how Earth works.

Two types of chemical bonds are particularly important in minerals,

Ionic and covalent

Why is gabbro considered a coarse-grained mafic rock? It is extremely rare. It contains a lot of feldspar. It contains a lot of silica. It contains a lot of magnesium and iron.

It contains a lot of magnesium and iron.

How would a metamorphic rock become a sedimentary rock?

It could experience weathering or erosion, later precipitating and undergoing lithification. Review the Rock cycle, Figure 3.12. Notice that a metamorphic rock can undergo weathering and lead to the formation of a sedimentary rock.

Which of the following statements is NOT true of a hypothesis? It is a widely accepted explanation for a phenomenon It may or may not be proven by experimental data It can be tested with scientific data It can provide predictions

It is a widely accepted explanation for a phenomenon

Why would a box on a shelf have a higher potential energy than that of a box on a lower shelf? The box on the lower shelf was placed there after the higher box. The box on the higher shelf is heavier It took more work to move the box to the high shelf than to the low shelf The box on the higher shelf experiences less gravitational pull; with less gravitational pull comes more weight, thus more potential energy.

It took more work to move the box to the high shelf than to the low shelf

Decompression melting occurs because Decreasing viscosity near the surface causes pressure to decrease Lower pressure results in a higher melt temperature Lower pressure results in a lower melt temperature Increasing temperature near the surface causes pressure to decrease

Lower pressure results in a lower melt temperature

Decompression melting occurs because Increasing temperature near the surface causes pressure to decrease Lower pressure results in a higher melt temperature Decreasing viscosity near the surface causes pressure to decrease Lower pressure results in a lower melt temperature

Lower pressure results in a lower melt temperature When hot mantle rises, it will reach a point at which the pressure of the overlying crust and mantle is lowered enough that the proper combination of pressure and temperature exists and partial melting occurs. Review Section 4.6.

What are the Properties of Minerals?

Luster Specific gravity is the ratio of the mass of a substance compared to the mass of the same volume of water. Density is the measure of the mass of a substance contained within a particular volume of the substance. Crystal faces Hardness Cleavage Color Streak

What process of igneous rock formation is most reflected by the size of the crystals? High pressure Fractional crystallization Lithification Magma cooling

Magma cooling

What process of igneous rock formation is most reflected by the size of the crystals?

Magma cooling Magma cooling rate determines grain size. A slow cooling rate results in large crystals (known as phaneritic texture). A fast cooling rate results in small crystals (known as aphanitic texture). Review Section 4.2 (subsection: second component in classification: texture).

2.2 What Makes Up Minerals?

Minerals, like all substances, are composed of atoms of chemical elements. Most minerals (e.g., quartz, calcite) are compounds, composed of two or more elements, although a few contain atoms of only one element (e.g., diamond, contains only carbon).

Why is water the universal solvent?

Molecules are slightly positively charged on one side and slightly negatively charged on the other.

Based on the information provided in Figure 4.18 all of the following interpretations/assertions are valid except: Pressure affects the temperature where melting begins. The water contents of melts change with changing pressure. There is a correlation between pressure and equivalent depth. Molten rock can solidify only by decreasing its temperature.

Molten rock can solidify only by decreasing its temperature.

How and where do rocks form?

Most natural rocks are aggregates of mineral grains. Many rocks originate from observable processes that take place at Earth's surface. The presence of rocks that are not related to observable surface processes suggests that they relate to processes active within Earth.

Does cubic zirconia fit the definition of a mineral? If not, specify which part of the definition does not apply to this material.

Not a mineral because it's not a naturally occurring solid

Which of the following is least affected by convection heating? wind a volcano erupting Earth's mantle rain

Rain Conduction, is the transfer of heat from a hot object to a cold object, like your warm feet to cold tile. There is no transfer of the heat with mass, but a transfer of heat from one mass to another during conduction. Please review Figure 1.14 for the difference between conduction, convection and radiation. These processes will play a significant roll in how Earth works.

Which of the following is a difference between a shield volcano and a composite volcano? Shield volcanoes are much hotter than composite volcanoes. Shield volcanoes' lava flows are thin and long whereas composite volcanoes' lava flows are thicker and shorter. Shield volcanoes have a much steeper slope than composite volcanoes. Shield volcanoes maximum height is much smaller than composite volcanoes.

Shield volcanoes' lava flows are thin and long whereas composite volcanoes' lava flows are thicker and shorter.

Which of the following is a difference between a shield volcano and a composite volcano? Shield volcanoes' lava flows are thin and long whereas composite volcanoes' lava flows are thicker and shorter. Shield volcanoes have a much steeper slope than composite volcanoes. Shield volcanoes are much hotter than composite volcanoes. Shield volcanoes maximum height is much smaller than composite volcanoes.

Shield volcanoes' lava flows are thin and long whereas composite volcanoes' lava flows are thicker and shorter.

Why does Silica content in most magmas range from 45 to almost 80 percent by weight?

Silica is made up of silicon and oxygen, two elements most prevalent in Earth's crust.

Why does Silica content in most magmas range from 45 to almost 80 percent by weight? Silica is very heavy and therefore throws off the percent weight. Silica is a very heavy gas. Silica is extremely light. Silica is made up of silicon and oxygen, two elements most prevalent in Earth's crust.

Silica is made up of silicon and oxygen, two elements most prevalent in Earth's crust.

Why does Silica content in most magmas range from 45 to almost 80 percent by weight? Silica is very heavy and therefore throws off the percent weight. Silica is made up of silicon and oxygen, two elements most prevalent in Earth's crust. Silica is extremely light. Silica is a very heavy gas.

Silica is made up of silicon and oxygen, two elements most prevalent in Earth's crust.

Which of the following is not one of the steps of magma formation at a convergent boundary? Subducted lithosphere is metamorphosed and water is released Water lowers the melting temperature of surrounding rocks, which then melt Oceanic lithosphere is subducted beneath continental crust Surrounding continental crust is subject to very high pressures

Surrounding continental crust is subject to very high pressures

Which of the following is not one of the steps of magma formation at a convergent boundary? Surrounding continental crust is subject to very high pressures Subducted lithosphere is metamorphosed and water is released Water lowers the melting temperature of surrounding rocks, which then melt Oceanic lithosphere is subducted beneath continental crust

Surrounding continental crust is subject to very high pressures

HDWK...How magma is made?

The ability to simulate the temperature, pressure, and compositional characteristics of the deep crust and mantle in the laboratory allows geologists to conduct experiments that portray the melting of rock and crystallization of magma. Tuttle and Bowen's experiments show that magma under higher pressure can contain more water, and the presence of water lowers the melting temperature of magma. Make sure to review Figure 4.18.

You examine 2 minerals specimens and find mineral a dissolves readily in water and min b apparently does not. What can we predict from this observation?

The answer is A. Mineral A must have bonds that break easily. Ionic bonds are easier to break than covalent bonds. Van der Waals are very weak forces.

Rock 1 has a volume of 15cm3 and a mass of 45 g. Rock 2 has a volume of 30cm3 and a mass of 60g which rock has a higher density?

The answer is A. Rock one has a density of 3g/cm3 (45g/15cm3). Rock 2 has a density of 2g/cm3 (60g/30cm3).

Which of the following is an example of conduction? A. soup boiling in a pot on the stove B. putting your bare feet onto cold tile C. pouring cream into hot coffee D. taking the cap off of your head

The answer is B. Choices A and C are examples of convection. D is an example of radiation. Remember that conduction is a transfer of heat from hot to cold, but convection is a transfer of heat along with the movement of the mass (like heat transferred to the soup and the soup moves).

Is beer a mineral?

The answer is B. No beer is not a mineral, it's both organic and a liquid.

Which of the following statements is false about wet melting

The answer is B. The subducting crust does NOT melt - the water comes off the slab under the right T and P conditions (metamorphic conditions).

Which of the following factors will cause a rock to melt?

The answer is C. You need to drop the pressure to get a rock to melt, review Figure 4.18b (and see the next clicker questions below)

How does fractionalized crystallization typically affect the chemistry of a sillicate magma?

The answer is D. Fractional crystallization always increases the silica content of the magma that has yet to solidify and water also tends to stay in the magma until the end of solidification.

Any rock can be turned into any other rock?

The answer is a. Any rock type can be converted into another via the rock cycle if the environment and conditions are met.

Weathering of rock can produce both clastic and chemical sediments

The answer is b. There is both physical and chemical weathering. Physical weathering produces fragments of rocks or minerals pieces (clastic sediments). Chemical weathering dissolves the minerals in the rock and can produce precipitates (chemical sediments).

There can be many theories to explain a natural process. a. True b. False

The answer is false. There can only be one BEST explanation to explain a natural process. If there are more than one, these would be hypotheses.

In order for an atom to substitute for dominant atoms in a crystal structure what must occur?

The atom must be similar in size to the crystal's atoms.: Review Section 2.6. For substitution to occur, elements should be similar in size and charge, but size is more critical than charge. Differences in charges can be accommodated with a double substitution, such as shown in Figure 2.25.

How are the rock classes related to one another? Emphasize this concept

The circular relationship of the three rock classes is portrayed as the rock cycle. Note how each rock group can be transformed into another by changing the environment, such as converting an igneous rock into a metamorphic rock during subduction processes at a convergent boundary. Think about the rock cycle in relationship to plate tectonic processes.

4.7 Why are igneous rock compositions so diverse?

The diversity of magmas solidifying to form igneous rocks can be the result of: Melting of equally diverse source rocks Deriving one magma composition from another - Fractional Crystallization (Review Fig 4.20) - EMPHASIZE THIS CONCEPT Magma Assimilation Magma Mixing

4.8 Why are there so many different types of volcanoes and volcanic eruptions?

The key to understanding volcanic phenomena rests in two properties of magma, gas content and viscosity, which are, in part, dependent on magma composition. Viscosity - A critical feature of magma is its viscosity, or resistance to flow. What are the relationship of gas content and viscosity to magma composition? How can magma composition determine the different types of volcanic eruptions and types of volcanoes?

One mineral is held together by ionic bonds and the other by covalent bonds. Which is stronger?

The one held together by covalent bonds is stronger.

Why does iron, when added to quartz, cause the purple color of amethyst?

The presence of trace constituents can affect color.

Why does manganese, when added to calcite, cause the mineral to turn a deep red?

The presence of trace constituents can affect color.

What is the scientific method?

The scientific method is the inquiring process that examines and explains a problem or observed phenomenon. It is not a cookbook recipe of steps.

Which of the following is a mineral?

calcite

An igneous rock is weathered down to rock fragments; what typically happens to the fragments?

They are transported and deposited into sediment banks, then undergoing lithification to form sedimentary rock. Typically, fragments can be transported by wind or water and accumulate in low areas. Eventually, these fragments can be compacted and glued together to form sedimentary rocks.

Why do felsic rocks typically have the lightest color? They contain pyroxene, amphibole, and plagioclase feldspar. They contain quartz, mica, amphibole, sodium-rich plagioclase feldspar, and potassium feldspar. They contain olivine, pyroxene, and calcium-rich plagioclase feldspar. They contain olivine and pyroxene.

They contain quartz, mica, amphibole, sodium-rich plagioclase feldspar, and potassium feldspar.

Why do felsic rocks typically have the lightest color? They contain quartz, mica, amphibole, sodium-rich plagioclase feldspar, and potassium feldspar. They contain pyroxene, amphibole, and plagioclase feldspar. They contain olivine and pyroxene. They contain olivine, pyroxene, and calcium-rich plagioclase feldspar.

They contain quartz, mica, amphibole, sodium-rich plagioclase feldspar, and potassium feldspar.

Why do felsic rocks typically have the lightest color? They contain olivine, pyroxene, and calcium-rich plagioclase feldspar. They contain pyroxene, amphibole, and plagioclase feldspar. They contain quartz, mica, amphibole, sodium-rich plagioclase feldspar, and potassium feldspar. They contain olivine and pyroxene.

They contain quartz, mica, amphibole, sodium-rich plagioclase feldspar, and potassium feldspar. Which minerals are dark in color and which are light in color? Minerals rich in iron (Fe) and Magnesium (Mg) are typically dark in color. Minerals rich in sodium or potassium feldspar and quartz are light in color. Using this information and the amounts of the minerals, the color of the rock can be used to give insight into the composition of the magma/rock.

Give an everyday analogy for uniformitarianism. How is this principle applied in geology?

This is known as uniformitarianism: the idea that Earth has always changed in uniform ways and that the present is the key to the past.

Evaluate the following statement: A sedimentary rock can be weathered, eroded and the resulting sediments transported and then lithified to form a new sedimentary rock.

True

Evaluate the following statement: Any rock type can be converted to another rock type through the rock cycle.

True

Minerals are the fundamental building blocks of Earth.

True

The Mohs hardness scale is a relative scale and not an absolute scale.

True

Evaluate the following statement - Almost all natural rocks are consolidated aggregates of minerals.

True Rocks can be made up of a single mineral, but are mostly aggregates of other minerals. So, a rock is made up of one or more minerals. An example of a rock made up of one mineral is limestone, which is made up of calcite.

Evaluate the following statement: Peridotite can melt at a divergent boundary at shallow depths because the pressure is lower, but the peridotite is still hotter than its surroundings. True False

True Very hot solid peridotite in the mantle rises toward the surface at divergent boundaries. At shallow depth the peridotite experiences lower pressure but is still hotter than its surroundings. The lower pressure results in a lower melting point and the peridotite starts to melt. Review Sections 4.4 (and look at Figure 4.16b), and 4.6 (and look at Figure 4.19a). Look at the active art associated with all of these figures.

The size of atoms in a mineral, and therefore how they pack together and bond to one another, determines the hardness of a mineral.

True: The composition determines the size of the atoms, which in turn determines the internal structure of how the atoms will pack themselves together and how they bond to one another. The internal structure and bonding will determine the hardness of a mineral. Review Section 2.1 for hardness, Section 2.3 for bonding, and Section 2.6 for how the atomic structure determines most physical properties.

How do we know? How to determine rock origins

Two competing views of rock-forming processes arose in the geological community of the late 1700s. Members of both intellectual camps appreciated the wearing down of rocky landscapes to make loose sand, gravel and mud, just as you readily observed those processes today. When it came, however, to explaining how consolidated, coherent rocks form, the two groups reached very different conclusions. The significance of the debate goes beyond the implications for classifying rocks. The dispute between those allied with Werner and those convinced otherwise by Hutton's arguments is an important development in the history of geology as a scientific discipline. This is because Hutton, as well as others, demonstrated the application of scientific method using observations of Earth materials and features. These observations, furthermore, appropriately tested hypotheses about the very origin of the planet.

4.6 How does magma generation connect to plate tectonics?

Typical geothermal gradients do not lead to sufficient temperatures at depth for much, if any, melting of mantle peridotite, since the melting temperatures of the rocks also increase with depth. The key, therefore, is to determine if there are processes that decrease the geothermal gradient (so that higher temperatures are reached at lower depths) or that decreases the melting temperature for the minerals in the rock. If these conditions can be met then melting will occur and magma will be generated. These conditions include: Melting by decreasing pressure (decompression melting) at divergent plate boundaries and "hot spots" Wet melting at subduction zones (make sure to understand the steps involved in getting wet melting to happen - see Fig. 4.19)

Which of the following statements is false: The melting temperature of wet granite decreases with increasing pressure The melting temperature of dry granite increases with increasing pressure Water content of magmas increase with increasing pressure Water raises the melting temperature at which magma is made from solid rock

Water raises the melting temperature at which magma is made from solid rock

What does the water molecule look like?

We use water, a covalently bonded compound to show how bonds break with minerals dissolve. Explain how here:

4.10 Why don't all magmas erupt?

When rocks partially melt, the resulting liquid magma is less dense than the remaining solids and rises. If, however, the magma encounters less dense rock as it ascends toward the surface, then the magma stalls and crystallizes. Rock temperature decreases as magma moves near the surface. If magma does not rise quickly, then its heat is conducted to surrounding rocks and the melt cools and crystallizes before it can erupt on the surface. Most water-rich magma crystallizes below ground because the magma solidifies as it releases dissolved water at shallow depths.

Plates move away from one another at neither a divergent, convergent nor transform boundary. a divergent boundary. a transform boundary. a convergent boundary.

a divergent boundary.

What is a mineral?

a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form occurs naturally in pure form

An igneous rock is fine-grained. What kind of rock is it, and how did it form?

a volcanic rock; it cooled quickly on the surface of the earth Volcanic rocks form when magma cools on the Earth's surface, and this makes their crystals small in size (fine-grained). Plutonic rocks cool within the Earth's crust, and with the added insulation of the surrounding crust, the crystals can grow larger (coarse-grained). So, grain size can be used to distinguish between the two types of igneous rocks.

Which pair of processes transforms sedimentary rocks to metamorphic rocks?

application of heat and pressure

Sedimentary rocks form

at Earth's surface environment.

To get a rock to turn into magma without changing the temperature significantly, the pressure must:a. go up (rock goes deeper into Earth) b. go down (rock rises to the surface)

b

Which of the following factors will cause rock to melt? a. High temperature, high pressure b. Low temperature, high pressure c. High temperature, low pressure d. Low temperature, low pressure

c

Which of the following statements about the scientific method is false? a. A scientific theory is never considered finally approved b. Data used to generate a hypothesis may come from observations, experiments, and chance findings c. A theory that has accumulated a substantial body of experimental support is called a hypothesis

c

A student breaks a piece of quartz and notices that it splits into irregular-shaped, jagged pieces, whereas calcite, when broken, will split into smooth, flat pieces. Which of the following properties of minerals is the student observing?

clevage

Uniformitarian principles cannot closely predict the timing of upcoming geologic events. predict where geologic events will likely occur in the future. forecast the severity of upcoming geologic events. accurately describe past events.

closely predict the timing of upcoming geologic events.

Uniformitarian principles cannot closely predict the timing of upcoming geologic events. forecast the severity of upcoming geologic events. accurately describe past events. predict where geologic events will likely occur in the future.

closely predict the timing of upcoming geologic events. Scientist use examined cases, whey they observe how a feature is formed and its results to infer about how a feature formed if only the results are observed. But the principle cannot predict when something will happen.

Igneous rocks formed below ground, compared to those formed above ground, are distinguished by

crystal size

Which of the following physical properties are affected by atomic spacing and bond strength?

density, hardness, cleavage

A scientist identifies a rock sample as rhyolite. Why did she do so? he observed that the sample has a lot of silica, making it felsic. He observed that the rock has a lot of silica, making it ultra-mafic. He observed that the rock has a lot of silica, making it mafic. He observed that the sample has little silica, making it felsic.

he observed that the sample has a lot of silica, making it felsic.

An explanation of a problem that accounts for existing data and predicts additional phenomena that should exist is called a principle hypothesis theory law

hypothesis

Freely roaming electrons in a material tend to make it a conductor of electricity. What other property do freely roaming electrons have an effect upon?

luster

You are given a metamorphic rock. From what previous rock type could it have come from?

metamorphic, igneous, or sedimentary

What type of crystal texture is formed when magma cools very slowly while surrounded by warm rock underground? porphyritic andesitic aphanitic phaneritic

phaneritic

What type of crystal texture is formed when magma cools very slowly while surrounded by warm rock underground?

phaneritic Aphanitic texture means that you can't see the crystals with the naked eye, which means that the rock cooled quickly, not slowly. Porphyritic texture has both large crystals and fine crystals. Andesite is a composition type or a rock name and not a texture (it's a fine-grained intermediate compositional igneous rock - see a picture of it in Figure 4.3). Please review Section 4.2.

Names given to the different types of igneous intrusions are attributed to their

shape and size Plutonic (or intrusive) igneous rocks form within Earth's crust. Where erosion exposes these rocks, they are commonly more resistant to weathering than the surrounding rocks. The means they stand out more as hills and ridges. These landforms are named based on their shapes and sizes. Please review Section 4.3, Figure 4.6 and Figure 4.7 along with associated active art.

A plutonic rock results from

slow cooling beneath the Earth's surface.

Identify the physical mineral property described. "The fine-grained nature of the powdery residue results in a more reliable observed color."

streak

Which sphere does not experience convection forces? the atmosphere the hydrosphere the biosphere the geosphere

the biosphere

Which sphere does not experience convection forces? the atmosphere the hydrosphere the biosphere the geosphere

the biosphere: Conduction, is the transfer of heat from a hot object to a cold object, like your warm feet to cold tile. There is no transfer of the heat with mass, but a transfer of heat from one mass to another during conduction. Please review Figure 1.14 for the difference between conduction and convection.

The three layers of Earth are the oceanic crust, the continental crust, and the upper mantle. the crust, the mantle, and the core. the crust, the upper mantle, and the lower mantle. the lithosphere, the asthenosphere, and the atmosphere

the crust, the mantle, and the core.

Which layer of earth is broken into discrete, hundred-kilometer-thick slabs called plates? the asthenosphere the lithosphere the mantle the crust

the lithosphere

In which ways does pressure influence different rock compositions' melting points? pressure changes the composition of the rock, lowering the melting point pressure changes the composition of the rock, raising the melting point the more pressure, the higher the melting point the more pressure, the lower the melting point

the more pressure, the higher the melting point

In which ways does pressure influence different rock compositions' melting points? pressure changes the composition of the rock, raising the melting point the more pressure, the higher the melting point pressure changes the composition of the rock, lowering the melting point the more pressure, the lower the melting point

the more pressure, the higher the melting point

A student notes that a rock contains mica and plagioclase feldspar and concludes that the rock is an intermediate rock. What piece of further information could best determine if the student's conclusion was the correct one?the silica content of the rock the grain size of the crystals the amphibole content of the rock the color of the rock

the silica content of the rock

Which of the following is not a way that atoms achieve a full outer layer of electrons?

transferring electrons from an inner level

The following are the two ways in which magma can be formed drop in pressure and an increase in the geothermal gradient change in composition of the rock and an increase in pressure wet melting and decompression decompression melting and increasing temperatures wet melting and subduction

wet melting and decompression

The following are the two ways in which magma can be formed drop in pressure and an increase in the geothermal gradient wet melting and decompression wet melting and subduction decompression melting and increasing temperatures change in composition of the rock and an increase in pressure Review Section 4.4 and Figure 4.16.

wet melting and decompression