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What causes a lack of cleavage in some minerals?
bonds of equal strength in all directions. A mineral will not have cleavage if there are not weaker bonds oriented in a particular direction
What mineral is not scratched by a fingernail, but is scratched by a copper penny?
The amount or quality of light that is reflected from a mineral surface is known as __?
What causes the same mineral to occur in varieties that are different colors?
Which of the following best describes the term, streak?
the color of a powdered form of a mineral produced by rubbing it across a hard surface
Since color is not a very useful way to identify a mineral, what other optical property of properties can be used?
The shape a mineral grows into, given sufficient space.
What discourages minerals from achieving habit?
Crystal habit is the shape that a mineral develops by the repetition of __?
Other than space, what 2 additional factors are significant for a crystal to attain habit?
Which pair is the most abundant in the continental crust?
Describe Aristotle’s influence on geology.
Believed that rocks were created under the influence of stars and that earthquakes occurred when air crowded into the ground, was heated by central fires, and escaped explosively. his beliefs unfortunately continued to be viewed as authoritative for centuries, inhibiting the acceptance of more up-to-date ideas
Contrast catastrophism and uniformitarianism. How did each view the age of the earth?
CAT-believed that earth’s landscapes were shaped primarily by great catastrophes
UNI- forces and processes that we observe presently shaping our planet have been at work for a very long time; “present is the key to the past”
HYP-gain facts and principles and try to explain how things happen in the manner they are observing. Construct a tentative explanation
THE- result of the hypothesis that has been well tested and accepted by the scientific community that best explains certain observable facts
Basic steps followed in scientific investigations.
2. data is collected for the ?
3. questions that relate to data are posed, and hypotheses are developed to answer ?
4. observations and experiment tests
5. hypotheses are accepted, modified, or rejected
6. data and results are shared to scientific community for examination and further testing
What explains the fact that continental drift is considered a hypothesis, but plate tectonics is considered a theory?
cont drift was the idea and after they had tested and examined it, they confirmed it as a theory bc they had proof and facts.
Hydrosphere- water portion
Atmosphere- gaseous/air envelope
geosphere- the solid earth
biosphere- all plant and animal life that interacts with all 3 spheres
Compare the height of the atmosphere to the thickness of the geosphere.
the solid earth (geosphere) is about 6400 (4000 miles), the atmosphere is a very thin layer.
How much of Earth’s surface do oceans cover? What percentage of Earth’s total water supply do oceans represent?
To which sphere does soil belong?
all 4 spheres: geosphere, biosphere, atmosphere, hydrosphere
What is a system? List 3 examples.
-group of interacting, or interdependent, parts that form a complex whole
-car cooling system, transportation system, weather system
What are 2 sources of energy for the Earth system?
Name and briefly outline the theory that describes the formation of our solar system.
nebular theory- proposes that the bodies of our solar system evolved from an enormous rotating cloud called solar nebula
Explain why density and buoyancy were impt in the development of Earth’s layered structure.
Hot temps caused iron and nickel to melt and produced liquid blobs of dense metal that sank toward the center of the earth producing Earth’s dense, iron-rich core. melting formed buoyant masses of molten rock that rose toward the surface, where they solidified producing a primitive crust
List and describe the 3 major layers defined by their chemical composition.
Crust- earth;s thin, rocky outer skin
mantle- solid, rocky shell that extends to a depth of about 2900 km (1800 miles)
Core- composed of an iron- nickel alloy w/ minor amounts of oxygen, silicon, and sulfer —elements that readily form compounds with iron
Contrast the litho and asthenosphere.
LITH- strong, consist of entire crust plus the uppermost mantle and forms outer shell
AST- soft, weak. Top portion results in some melting
Compare and contrast continents and ocean basins.
CON- flat, appearance of plates protruding sea level. average elevation of .8 km. Lie close to sea level. 35 km in thickness and composed of granite rocks
OB- depth of ocean floor is 3.8 km below sea level, basaltic rocks are 7 km thick
Describe the general distribution of Earth’s youngest mnts.
100 mil yrs old. located in circum-pacific belt includes the mnts of the western americas and continues into western pacific in the form of volcanic arcs.
What is the difference between shields and stable platforms?
flat areas of crayon in stable platforms are covered by a thin veneer of sed. rocks, flat regions in shields are composed of deformed igneous and met. rocks
What are the 3 major regions of the ocean floor, and what are some features associated with each?
1. Continental margin- adjacent to major landmasses; includes cont. shelf, cont. slope and cont. rise
2. Deep-Ocean basins- between cont margins and ocean ridges; includes abyssal plains, deep-ocean trenches and seamounts
3. Ocean ridges- most prominent feature on the ocean floor; forms a continuous belt that winds for more than 70,000 km; consists of layer upon layer of igneous rock that has been fractured and uplifted
What was the first line of evidence that led early investigators to suspect that the continents were once connected?
Explain why the discovery of the fossil remains of mesosaurus in both SA and Africa, but nowhere else, supports the con drift hypothesis.
bc if mesosaurus would have been able to make the journey across the south atlantic, its remains would be more widely distributed, so SA and Africa must have been joined during that period of the earth history
Early in the 20th century, what was the prevailing view of how land animals migrated across vast expanses of open ocean?
rafting, transoceanic land bridges, and island stepping stones
How did Wegener account for the existence of glaciers in the southern landmasses at a time when areas in NA, Europe, and Asia supported lush tropical swamps?
Pangaea. The southern continents are joined together and located near the south pole.
What 2 aspects of Wegener’s cont drift hypothesis were objectionable to most earth scientists?
inability to identify a credible mechanism for cont drift and the larger and sturdier contents broke through thinner oceanic crust, much as ice breakers cut through ice
What major ocean floor feature did oceanographer discover after WW2?
List the 7 largest lithospheric plates.
NA, SA, Pacific, African, Eurasian, Australian-Indian, and antarctic
List the 3 types of plate boundaries and describe the relative motion of each.
1. Divergent (constructive): 2 plates move apart forming new ocean floor
2. Convergent (destructive): 2 plates move together resulting in oceanic lith descending beneath an overriding plate, or collision of the 2 cont blocks to create a mnt belt
3. Transform (conservative): 2 plates grind past each other w/out destruction of lith.
What is the average rate of seafloor spreading in modern oceans?
5 cm (2 in) per year
Briefly describe the process of continental rifting. Where is it occurring today?
-Tectonic forces continue to pull apart the crust, the broken crustal fragments drop, generating an elongated depression
-East African Rift
Compare a continental volcanic arc and a volcanic island arc.
CVA- produced in part by volcanic activity associated with the subduction of oceanic lithosphere
VIA- subduction is sustained, it will eventually build a chain of volcanic structures large enough to emerge as islands. Arc-shaped chain of volcanic islands
Describe the process that leads to the formation of deep ocean trenches.
cont lith is less dense and resists subduction. As a consequence, only oceanic lithosphere will subduct to great depths.
Why does the oceanic lith subduct, while cont lith does not?
bc OL is about 2% more dense than the underlying asthenosphere. CL is less dense and resists sinking
Briefly describe how mtn belts such as the himalayas form.
subcontinent of india rammed into asia. The cont crust buckled and fractured and was generally shortened horizontally and thickened vertically.
Describe how 2 plates move in relation to each other along a transform plate boundary.
they connect to each other and the boundary facilitates the movement of crustal material to its destination
What is the age of the oldest sediments recovered using deep ocean drilling? How do the ages of these sediments compare to the ages of the oldest continental rocks?
What do transform faults that connect spreading centers indicate about plate motion?
transform faults yield the direction of plate movement
Describe slab pull and ridge push. Which of these forces appears to contribute more to plate motion?
SP- subduction of cold, dense slabs of oceanic lith are more dense than the underlying warm asthenosphere
RP- results from the elevated position of the oceanic ridge, which causes slabs of lith to “slide” down the flanks of the ridge
What roles of Mantle plumes are thought to play in the convective flow in the mantle?
the downward flow is balanced by buoyant rising mantle plumes that transport hot materials to the surface
List 5 characteristics an Earth material must have in order to be considered a mineral.
2. generally inorganic
3. solid substance
4. Orderly crystalline structure
5. Def. chemical composition that allows for some variation
Based on the definition of a mineral, which of the following materials are not classifies as minerals, and why: gold, water, synthetic diamonds, ice, and wood.
water- it’s not solid
synthetic diamonds- produced in a lab or humans
Define rock. How does it differ from minerals?
-any solid mass of mineral or mineral like matter that occurs naturally as part of our planet
List the 3 main parts of an atom and list how they differ from one another.
protons- charge of +1
neutrons- charge of 0
electrons- charge of -1
What is the significance of valence electrons?
in the outer shell that interact with other atoms to form chemical bonds
What is the difference between an atom and an ion?
atoms cannot be chemically split; ion caontains pos and neg charged atoms
What occurs in an atom to produce a pos ion? A neg ion?
pos-loses electons neg-gains electrons
Briefly distinguish between ionic and covalent bonding and the role that electrons play in each type of bond.
I-attraction of oppositely charged ions producing an electrically neutral ionic cmpnd
C- formed by sharing of one or more valence electrons between a pair of atoms
List 3 ways minerals and rocks can form.
1. Precipitation of mineral matter
2. Crystallization of molten rock
3. Mineral matter deposition as a result of biological processes
Crystallization from molten rock produces which one of the 3 types of rock?
What is the chemical composition of the mineral matter secreted by most organisms? What is the name a mineral and a rock that results from this process?
-calcium carbonate (CaCO3)
-sedimentary rock limestone? reefs?
Why does basaltic lava have the lowest viscosity?
Basaltic lava is hotter than other flows.
What is the difference between magma and lava?
Location: the former is molten rock underground whereas the latter is molten rock at the Earth's surface.
What property of the asthenosphere makes it weak?
The asthenosphere is weak due to the weight of the overlying crust.
Keeping in mind the shape of magnetic field lines in space around the Earth, which of the following is true?
The seven principal classes of minerals are distinguished from each other based on ....
In the Atlantic Ocean, where does the youngest oceanic crust occur?
Adjacent to the mid-ocean ridge.
Which of the following statements about Wegener’s reconstruction of late Paleozoic Pangaea is true?
Areas glaciated during the late Paleozoic laid over the south polar region at the time.
Why did iron differentiate into the core?
Iron has a high density compared with other elements in the Earth.
What type of plate boundary is associated with Mid Ocean Ridges?
Earth is one of 4 inner planets. These planets are ...
he continents we see today were once a single continent. How long did it take for the single continent to break apart and form the arrangement of continents seen today?
. Most earthquakes occur at..
() forces have the greatest influence on the velocity of plate motion.
Physicists have concluded which of the following concerning element formation?
Hydrogen and helium formed during the big bang, but heavier elements formed later, through fusion reactions in stars, including supernova explosions.
Which of the following processes happens at the axis of a mid-ocean ridge?
a. Stretching force causes the crust to break and slip on normal faults. b. Hot asthenosphere rises.
According to the big-bang theory . . .
everything that now comprises the Universe started at a single point about 13 billion years ago.
What do muscovite and biotite have in common?
Is the temperature the same everywhere inside the Earth?
No. The temperature increases with increasing depth.
1. Talc, graphite
2. Gypsum (fingernail)
3. Calcite (copper penny)
5. Apatite (glass)
6. Orthoclase (steel file)
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