Earth Science Semester 1 Exam

Chapter 3

chapter 3

List two characteristics an Earth material must have in order to be considered a mineral.

-Naturally occurring -Generally inorganic -Solid substance -orderly crystalline structure -definite chemical composition that allows for some variation.

Jupiter, the largest planet in our solar system, is 5.2 astronomical units (AU) from the Sun. How long would it take to go from Earth to Jupiter if you traveled as fast as a jet (1000 kilometers/hour)? Do the same calculation for Neptune, which is 30 AU from the Sun. Referring to the GEOgraphics feature on page 15 will be helpful.

1 AU = 150 million km. 5.2 AU × 150,000,000 km = 780,000,000 km 780,000,000 km × hour/1000 km = 780,000 hrs = 32,500 days = 89 years Neptune: 30 AU × 150 million km = 4.5 billion km 4.5 billion km × hour/1000 km = 4,500,000 hours = 187,500 days = 513.7 years

If you compress geologic time into a single year, how much time has elapsed since Columbus arrived in the New World?

3 seconds.

How old is Earth?

4.6 billion years

What is a system? List three examples of systems.

A system is a group of interacting, independent parts that make up a complex whole. Examples of systems include a city transportation system, a weather system, or an automotive cooling system.

What is the difference between an atom and an ion?

An atom does not have a charge because it has an equal number of protons or electrons. Ions have either given up or taken on more electrons, giving the ion a positive or negative charge.

Predict how a change in the hydrologic cycle, such as increased rainfall in an area, might influence the biosphere and geosphere in that area.

An increase in rainfall might affect the biosphere by changing the amount and types of vegetation found in that area. In turn, the vegetation change could alter the types of animals that inhabit the region. Increasing the rainfall could affect the geosphere by increasing erosion. Conversely, if vegetation increases also, the plants could be a stabilizing factor that decreases erosion.

Distinguish between conglomerate and breccia.

Both are made of large sized sedimentary grains. However, conglomerate consists of grains that have been rounded before compaction and breccia contains angular grains of rock and minerals.

What is the most common carbonate mineral?

Calcite

List eight common nonsilicate minerals and their economic uses.

Calcite - Portland cement, lime Halite - salt Fluorite - steelmaking Hematite - Ore of iron Galena - Ore of lead Sphalerite - Ore of zincChalcopyrite - Ore of copper Silver - Jewelry

List three common cements. How might each be identified?

Calcite - effervesces when a drop of weak HCl is placed on it. Silica - hardest cement, will scratch glass. Iron oxide - oxidizes to a rusty red color.

List six common nonsilicate mineral groups. What key ion(s) or element(s) define each group?

Carbonates - CO3 ion Halides - F, Cl, Br Oxides - O Sulfides - S Sulfates - SO4 ion Native elements - various single elements such as gold and copper.

Chapter 2

Chapter 2

What are the two categories of chemical sedimentary rock? Give an example of a rock that belongs to each category.

Chemical and biochemical. A chemical sedimentary rock is travertine limestone. Another is chert. A biochemical rock is coquina or coal.

Explain how a mineral deposit that previously could not be mined profitably might be upgraded to an ore deposit.

Demand for a metal may increase its value or technological advances may make it more profitable to extract the metal than previously.

To which sphere does soil belong?

Geosphere

Aside from natural hazards, describe another important connection between people and Earth science. Humans influence Earth by altering its surface. People build cities and roads, and engineer projects that alter river flooding patterns. People pollute the air, the land, and the water, changing Earth from what is its natural state.

Humans influence Earth by altering its surface. People build cities and roads, and engineer projects that alter river flooding patterns. People pollute the air, the land, and the water, changing Earth from what is its natural state.

List the inner planets and the outer planets. Describe basic differences in size and composition.

Inner planets: Mercury, Venus, Earth, and Mars. These planets are relatively small and rocky; they are made up largely of metals and silicate minerals. Outer planets: Jupiter, Saturn, Uranus, and Neptune. These planets are much larger than the inner planets and are composed of ices and gases.

What is the most characteristic feature of sedimentary rocks?

Layers, or strata as these rocks are laid down.

What are lithospheric plates? List the three types of boundaries that separate plates.

Lithospheric plates are the broken up slabs of Earth's rigid outer shell, the lithosphere. The three types of plate boundaries are divergent, convergent, and transform fault.

Define luster.

Luster describes the quality of light reflected from a mineral's surface. It may be metallic or nonmetallic, with several subdistinctions among nonmetallic lusters.

What is magma? How does magma differ from lava?

Magma is liquid, molten rock. It is found underground, whereas lava is found extrusively, or outside Earth's interior.

Briefly describe what is meant by the statement "every metamorphic rock has a parent rock."

Metamorphic rocks are existing rocks that have been altered by heat and/or pressure. Therefore, every metamorphic rock was another type of rock, the parent rock, initially.

How much of Earth's surface do oceans cover? How much of the planet's total water supply do oceans represent?

Oceans cover 70% of the planet. They account for 97% of Earth's water supply.

List the three main particles of an atom and explain how they differ from one another..

Proton - positively charged particle in the nucleus of the atom. The number of protons is the same as the element number. Neutron - particle in the nucleus of the atom. It has no charge associated with it. Electron - negatively charged particle that orbits the nucleus. There are the same number of electrons as protons in a given element.

What simple chemical test is useful in the identification of the mineral calcite?

Putting a drop of weak acid, such as HCl, on the mineral will create a visible reaction with bubbling on the surface.

What minerals are most abundant in detrital sedimentary rocks? In which rocks do these sediments predominate?

Quartz and clay minerals, especially from feldspars, are most abundant. These rocks predominate in conglomerate, breccia, sandstone, arkose, siltstone, and shale.

List three examples of renewable resources and three examples of nonrenewable resources.

Renewable - solar, forests and trees, water Nonrenewable - Metals, oil, coal

Define the term rock. How do rocks differ from minerals?

Rocks are more loosely defined as aggregates of different minerals. Rocks differ from minerals because they may be of varied mineral content and they may contain non-mineral matter.

Why are sedimentary rocks important?

Sedimentary rocks contain almost all of the fossil record. Sedimentary rocks make up about 75% of continental rock outcrops and contain clues to the history of the Earth's surface. They also have economic importance; for example coal is a sedimentary rock and other natural resources are extracted from sedimentary rocks

Referring to the accompanying photos (top of pg. 57) of five minerals, determine which of these specimens exhibit a metallic luster and which have a nonmetallic luster.

Specimens A, B, and D have a nonmetallic luster. Specimens C and E have a metallic luster.

What are the two sources of energy for the Earth system?

The Sun and Earth's interior.

What is the significance of valence electrons?

The valence shell of an atom is its outermost shell and responsible for bonding with other atoms. The electrons of the valence shell are those that are shared with other atoms in the bonding process.

Describe the general distribution of Earth's youngest mountains.

They are at the margins of continents.

Gold has a specific gravity of almost 20. A 5-gallon bucket of water weighs 40 pounds. How much would a 5- gallon bucket of gold weigh?

5 gallons of water = 40 lbs. × 20 (specific gravity of gold) = 800 lbs.

The length of recorded history for humankind is about 5000 years. Clearly, most people view this span as being very long. How does it compare to the length of geologic time? Calculate the percentage or fraction of geologic time that is represented by recorded history. To make calculations easier, round the age of Earth to the nearest billion.

5000/5,000,000,000= 0.000001%

How is a scientific hypothesis different from a scientific theory?

A hypothesis is an untested explanation for an observed phenomenon. It requires further observation or testing to see if it is valid. A theory is generally accepted by the scientific community as the best explanation for observable facts, as it has been subjected to rigorous scrutiny and tested repeatedly.

List two examples of size/place scales in Earth science that are at opposite ends of the spectrum.

A lightning flash happens within a fraction of a second but can instantly alter the immediate landscape. Uplift of mountain ranges takes tens to hundreds of millions of years to occur.

What does a porphyritic texture indicate about the history of an igneous rock?

A porphyritic texture, where the rock has some large and some small crystals, indicates that the rock started to cool slowly and then experienced a change of environment or cooling temperature where the rest of the rock cooled more quickly.

What is the difference between shields and stable platforms?

A shield is a large stable area of very old crystalline rock. A stable platform is a shield covered by sedimentary rock.

What occurs in an atom to produce a positive ion? A negative ion?

An atom that has given up one or more valence electrons becomes a positive ion. An atom that has taken on extra valence electrons becomes a negative ion.

Summarize the basic steps followed in many scientific investigations

An observation is made about the natural world. Data surrounding that observation are collected. A working hypothesis is developed. More observations and/or experiments are performed to test the hypothesis. The hypothesis is accepted, rejected, or modified. Data and results are shared with the scientific community for critical analysis and further testing.

List Earth's four spheres.

Atmosphere Hydrosphere Biosphere Geosphere

What differentiates cleavage from fracture?

Cleavage occurs when a mineral breaks cleanly along a plane. This is due to a plane of weak atomic bonding within the mineral. Fracture occurs when there is no distinct plane along which the mineral can break; when hit with a rock hammer, the mineral will fracture into irregular pieces.

What mineral property is illustrated in the accompanying photo?

Cleavage.

Describe the two processes by which sediments are transformed into sedimentary rocks. Which is the most effective process in the lithification of sand and gravel-sized sediments?

Compaction occurs where pressure is placed on loosely packed sediment. Volume of the sediment is reduced and water is squeezed out. Cementation occurs when mineral-bearing water circulates among the grains, hardens, and cements the sediment grains together. This process is most effective for lithifying sand and gravel-sized sediments.

What are the three major regions of the ocean floor and some features associated with each region?

Continental margins - contains the continental shelf, the continental slope, and the continental rise. It is the boundary between continents and oceans. Deep-ocean basins - these include the vast, flat abyssal plains of the ocean bottom. They also contain deep ocean trenches and seamounts in varied stages of erosion. Oceanic ridges - these are divergent plate boundaries where new igneous rock is formed. These are vast winding ridges of underwater volcanic mountains that wind around the Earth.

Contrast continents and ocean basins.

Continents are made of granitic rocks whereas oceans are made of basaltic rocks. Continents are less dense and thicker than ocean basins.

List and briefly describe Earth's compositional layers.

Crust - this is the outermost layer of Earth. It is very thin and made up of oceanic and continental types of crust. Mantle - this is a semi-molten, relatively thick layer of Earth. It is divided into the upper and lower mantle and its semi-fluid state allows for plate tectonics. Core - this is at the center of Earth. The inner core is solid nickel and iron, whereas the outer core is liquid. It is the thickest of all Earth's structural layers.

How do evaporites form? Give an example.

Evaporites form when minerals are dissolved in solution, and the water of that solution evaporates away. One example is rock salt.

How does the rate of cooling influence crystal size? What other factors influence the texture of igneous rocks?

Faster cooling correlates with smaller crystal size. Other influential factors include the composition of the magma and the presence of gases, such as in a volcano, that can cause a vesicular texture.

What is the most abundant mineral in Earth's crust?

Feldspar

Making accurate measurements and observations is a basic part of scientific inquiry. The accompanying radar image, showing the distribution and intensity of precipitation associated with a storm, provides one example. Identify another image in this chapter that illustrates a way in which scientific data are gathered. Suggest an advantage that might be associated with the example you select.

Figure 1.7 shows a paleontologist collecting fossils. An advantage of fossil data is that it is concrete and observable. Fossils can be used to tell about the past climate of an area and they can be used to help determine the age of the rocks in which it was found, and the ages of surrounding rocks.

List and briefly describe the sciences that collectively make up Earth science.

Geology - this is the study of the solid Earth. Physical geology examines the materials that comprise the Earth and historical geology aims to understand the origins and development of the planet. Oceanography - examines the composition and dynamics of the world's oceans. It also involves the study of coastal processes and seafloor topography as well as marine life. Meteorology - this is the study of Earth's atmosphere. It includes weather and climate. Astronomy - this examines Earth as a body in space, both as part of the solar system and as part of a larger universe. Environmental science - includes the study of natural resources, environmental hazards, and how people influence their environments and Earth processes.

How are granite and rhyolite different? In what way are they similar?

Granite has a phaneritic, or coarse-grained texture whereas rhyolite is aphanitic, or fine-grained. They are compositionally similar, being granitic or felsic rocks. They could be from the same magma type but rate of cooling has affected their crystal sizes.

List and distinguish among the four basic compositional groups of igneous rocks.

Granitic - felsic or light colored rocks where the dominant minerals are quartz and potassium feldspar. Andesitic - intermediate rocks where the dominant minerals are amphibole and plagioclase. These are neither light nor dark. Basaltic - mafic or dark colored rocks with high amounts of magnesium and/or iron. The dominant minerals are pyroxene and plagioclase feldspar. Ultramafic - these are uncommon rocks with very high amounts of magnesium and/or iron. The dominant minerals are olivine and pyroxene.

List the four agents of metamorphism and describe the role of each.

Heat - triggers chemical reactions that result in recrystallization of existing minerals and formation of new minerals. Confining pressure - buried rocks experience even pressure from all directions, which creates a more compact, denser rock. Differential stress - often occurs during mountain building where rocks experience unequal forces from different directions. This creates rocks that have been deformed, often with flattened mineral grains. Chemically active fluids - ion-rich fluids invade the rock and enhance ion migration. Often hot, these fluids can generate mineral recrystallization.

In what basic settings do intrusive and extrusive igneous rocks originate?

Intrusive igneous rocks cool below the surface of the Earth. Extrusive igneous rocks cool outside the Earth's interior.

Briefly distinguish among ionic, covalent, and metallic bonding and describe the role that electrons play in each.

Ionic bonding - one atom "donates" its electrons to another, creating two ions bonded to each other. Covalent bonding - two atoms equally share valence electrons. Metallic bonding - several atoms contribute their valence electrons to a pool of electrons that are free to move through the entire structure.

What is magmatic differentiation? How might this process lead to the formation of several different igneous rocks from a single magma?

Magmatic differentiation occurs as magma cools and crystals of minerals with higher melting temperatures crystallize out of the magma, changing the magmatic composition. By depleting the magma, or melt, of these minerals, the next rocks to form from the cooling magma will have a different composition than those that formed at higher temperatures.

Compare and contrast a mineral resource and an ore deposit.

Mineral resources are occurrences of useful minerals in such large amounts that extraction is reasonably certain. An ore deposit is a naturally occurring concentration of one or more minerals with economic value. Mineral resources include deposits that are not economically viable to recover where ore deposits are.

Metamorphism means "change form." Describe how a rock may change during metamorphism.

Mineralogy, texture, and sometimes chemical composition may change. Intense heat and/or pressure will alter the grains of the original rock, whether it is igneous, sedimentary, or metamorphic.

List the eight most common elements in Earth's crust, in order of abundance (most to least).

Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium.

Name the two broad subdivisions of geology and distinguish between them.

Physical geology - this is the study of the materials and processes that define the planet Earth. It includes the study of Earth's composition, events such as volcanism, and the dynamics of Earth processes such as plate tectonics. Historical geology - this is the study of the origins and evolution of Earth. It pieces together a chronological history of Earth based on clues in the rock record. These clues can include evidence of physical and biological changes throughout Earth's 4.6 billion year history.

Explain the difference between silicon and silicate.

Silicon is an element. Silicates contain silicon and oxygen and are the major constituents of continental crust.

Which of the following elements is more likely to form chemical bonds: xenon (Xe) or sodium (Na)? Explain why.

Sodium is more likely to form chemical bonds because of its tendency to lose one electron, resulting in an overall +1 charge.

What do we mean when we refer to a mineral's tenacity? List three terms that describe tenacity.

Tenacity is a mineral's resistance to cutting, breaking, and other forms of deformation. Three terms that describe tenacity are brittle, malleable, and sectile. Elastic is another term.n. persistence perseverance determination

Compare the height of the atmosphere to the thickness of the geosphere.

The atmosphere is a very thin layer compared to the planet itself. The radius of the solid Earth is about 6400 km (4000 mi) whereas the entire atmosphere is roughly 160 km (100 mi) thick.

Contrast the lithosphere and the asthenosphere.

The lithosphere is the relatively cool, hard, outer shell of Earth's crust. The asthenosphere is relatively soft and has some melting in its upper layer. The different natures of these two layers, which are in contact with each other, is what allows for plate tectonics, where the hard lithosphere moves on the semi-fluid upper portion of the asthenosphere.

Name and briefly outline the theory that describes the formation of our solar system.

The nebular theory states that the early solar system originated as a cloud of dust and gas about 5 billion years ago as a star gravitationally collapsed. This rotating nebular cloud eventually contracted into a flattened, rotating disk. The cloud cooled and heavier metallic and rocky material condensed and accreted into the inner . The outer planets formed from residual gases and ices in the outer nebular cloud.

These rock layers consist of materials such as sand, mud, and gravel that, over a span of millions of years, were deposited by rivers, waves, wind, and glaciers. Each layer was buried by subsequent deposits and eventually compacted and cemented into solid rock. Later, the region was uplifted, and erosion exposed the layers seen here. a. Can you establish a relative time scale for these rocks? That is, can you determine which one of the layers shown here is likely oldest and which is probably youngest? b. Explain the logic you used.

The oldest rock is on the bottom and the youngest is on the top. Each layer was put down successively; therefore newer rock kept building upon the rock already in place.

Use the rock cycle to explain the statement "One rock is the raw material for another."

The rock cycle illustrates that any rock type can be transformed into any other rock type. As an example, igneous rocks may be weathered and compacted into sedimentary rocks. Those sedimentary rocks may be subjected to heat and pressure to become metamorphic rocks. Depending upon the conditions, rocks can be continually transformed into different types of rock.

After entering a dark room, you turn on a wall switch, but the light does not come on. Suggest at least three hypotheses that might explain this observation. How would you determine which one of your hypotheses (if any) is correct?

There is a local power outage. The light source (bulbs, tubes, etc.) is "burned out" and no longer working. The electricity to the room is not turned on or has been disconnected. You can determine which of these is correct by testing the hypothesis. For example, you can replace the light bulb with a new one to see if it works. You can look at the circuit breakers and see if any of them are not on. You can call the electric company to see if service has been discontinued or if there are general power outages in your area.

Why is color not always a useful property in mineral identification? Give an example of a mineral that supports your answer.

There may be small impurities in the mineral that will alter its color. Quartz is a notable example, with rose quartz (pink) and amethyst (purple) being only two examples of color variants.

Examine the accompanying photo of a cleaved sample of a mineral (pg. 57) that has several smooth, flat surfaces that resulted when the specimen was broken. a. How many flat surfaces are present on this specimen? b. How many different directions of cleavage does this specimen have? c. Do the cleavage directions meet at 90-degree angles?

a. 6 b. 3 c.no

Refer to the graph in Figure 1.13 in your book to answer the following questions. a. If you were to climb to the top of Mount Everest, how many breaths of air would you have to take at that altitude to equal one breath at sea level? b. If you are flying in a commercial jet at an altitude of 12 kilometers (about 39,000 feet), about what percentage of the atmosphere's mass is below you?

a. Air pressure at the top of Mount Everest is about 1/3 that at sea level, so you would need to take 3 breaths relative to sea level. b. About 75% of the atmosphere's mass is below you.

Examine Figure 1.12 in your book to answer these questions. a. Where is most of Earth's freshwater stored? b. Where is most of Earth's liquid freshwater found?

a. Glaciers b. Groundwater

Each of the following statements describes a silicate mineral or mineral group. In each case, provide the appropriate name. a. The most common member of the amphibole group b. The most common light-colored member of the mica family c. The only common silicate mineral made entirely of silicon and oxygen d. A silicate mineral with a name that is based on its color e. A silicate mineral that is characterized by striations f. A silicate mineral that originates as a product of chemical weathering

a. Hornblende b. Muscovite c. Quartz d. Rose quartz e.feldspar f.calcite

Each of the following statements may either be a hypothesis (H), a theory (T), or an observation (O). Use one of these letters to identify each statement. Briefly explain each choice. a. A scientist proposes that a recently discovered large ring-shaped structure on the Canadian Shield is the remains of an ancient meteorite crater. b. The Redwall Formation in the Grand Canyon is composed primarily of limestone. c. The outer part of Earth consists of several large plates that move and interact with each other. d. Since 1885, the terminus of Canada's Athabasca Glacier has receded 1.5 kilometers.

a. Hypothesis - it is a tentative explanation b. Observation c. Theory - well tested and widely accepted by the scientific community d. Observation - direct measurement of how far the glacier has moved

Assume that the number of protons in a neutral atom is 92 and its mass number is 238. a. What is the element? b. How many electrons does it have? c. How many neutrons does it have?

a. The element is uranium. b. 92 electrons c.146 neutrons

Using the geologic definition of mineral as your guide, determine which of the items in this list are minerals and which are not. If something in this list is not a mineral, explain. a. gold b. seawater c. quartz d. cubic zirconia e. obsidian f. ruby g. glacial ice h. amber

a. mineral - gold is an example of a mineral classified as a native element; b. seawater is not a mineral - minerals by definition are solids; c. quartz is a mineral; d. cubic zirconia is not a mineral - it is not naturally occurring; e. obsidian is not a mineral because it lacks an internal arrangement of atoms, however, it is an igneous rock; f. ruby is a mineral - it is a gemstone variety of the mineral corundum; g. glacial ice is a mineral as it meets all of the criteria; h. amber is not a mineral since it has an organic origin.

List at least four different natural hazards.

volcanoes, floods, tsunami, earthquakes, landslides, and hurricanes.