GEOLOGY 1500 FINAL EXAM
QUESTIONS & ANSWERS(RATED
A+)
Define Mechanical Weathering - ANSWERthe physical breakdown or disintegration
of rocks and minerals into smaller and smaller pieces with no chemical change
Define Chemical Weathering - ANSWERdecomposition of rocks and minerals into
new minerals and substances due to the presence of water (H20), oxygen (O2), and
hydrogen ions (H+)
Role of Weathering in the Rock Cycle - ANSWERattacks any Earth materials
(minerals and rocks) that are exposed by Uplift and Erosion at/near the Earth's
surface
What is the source of energy for weathering process? - ANSWERSolar
Energy/Radiation
One way in which the water molecule promotes both chemical and mechanical
weathering - ANSWER-promotes chemical weathering because it dissolves many
substances due to the polar nature of the water molecule.
-promotes mechanical weathering because it expands by about 9% when it freezes
thus causing rocks to be broken into smaller pieces
5 mechanical weathering processes - ANSWERFrost Action or Wedging
Stress Release/Pressure Release
Salt Weathering-- Crystal Growth
Thermal Expansion and Contraction
Organic Activity or Bio-Mechanical Activity
Describe how Stress Release-Mechanical Exfoliation leads to Mechanical
Weathering and what type of landform results from Stress Release-Mechanical
Exfoliation - ANSWER-opens large fractures in ricks and allows other processes to
operate
-exfoliation domes
What is TALUS? - ANSWERcoarse, angular rock material that accumulates at the
base of a slope or cliff--results from a combination of frost wedging and rock falls
How and why does Mechanical Weathering enhance Chemical Weathering? -
ANSWERMechanical Weathering breaks rocks and minerals down into smaller and
smaller pieces, which provides more surface area for chemical weathering to take
place on (work together to break down rocks)
5 factors that influence Chemical Weathering - ANSWERClimate
, Rock Structure
Organic Activity
Time
Mineral and Rock Composition
(all other factors being equal) What global climate belt would you expect to observe
the fastest rates of Chemical Weathering? Why? - ANSWER-Tropical Climate
Zone/Belt
What are the primary substances necessary for Chemical Weathering? -
ANSWERWater, Oxygen, and Hydrogen Ions
What is the primary source of hydrogen ions? - ANSWERdissociation of carbonic
acid that forms as a result of dissolution of carbon dioxide in water
List and define the 3 Chemical Weathering Processes or Reactions. What type of
rock(s) that each process/reaction breaks down. - ANSWER-Dissolution: a Chemical
reaction whereby ions pass from a mineral into a solution; breaks down Limestone,
Dolostone, Marble, Rock Salt, and Rock Gypsum
-Hydrolysis: a Chemical Reaction in which Water dissociates into H+ (hydrogen
cation) and OH- (hydroxide anion); breaks down feldspars and micas in many types
of Igneous and Metamorphic Rocks
-Oxidation: a Chemical reaction in which oxygen as an oxidizing agent causes a loss
of electrons by an atom or ion and thus involves an increase in oxidation number;
breaks down Ferromagnesian minerals in Mafic Igneous Rocks and their
Metamorphic Equivalents.
For the following types of Chemical Weathering Reactions/Processes, what Gas is
removed from the atmosphere for each reaction/process, and what Substances are
needed for the reaction to take place? - ANSWER-Dissolution: CO2; Water and
Hydrogen Ions
-Hydrolysis: NONE; Water and Hydrogen Ions
-Oxidation: O2; Oxygen
For the following types of Chemical Weathering Reactions/Processes, what New
Products (especially insoluble residues) are the result of each type of Reaction? -
ANSWER-Dissolution: No Residue - All Soluble Ions-ultimately all material is totally
dissolved
-Hydrolysis: Insoluble Residue = Clay Minerals; some other material is dissolved
-Oxidation: Insoluble Residue = Iron Oxides (Hematite, Limonite, Goethite); some
other material is dissolved.
For Chemical Weathering list the following groups of minerals from Most Stable to
Least Stable: Assume that they are undergoing Chemical Weathering in the same
climate. - ANSWERMost to Least Stable: Quarts, Muscovite, Na-Plagioclase,
Pyroxene, Olivine
Most to Least Stable: Limonite, Clay
17. For Chemical Weathering list the following groups of Igneous and Metamorphic
Rocks from Most Stable/Most Resistant to Least Stable/Least Resistant to Chemical
QUESTIONS & ANSWERS(RATED
A+)
Define Mechanical Weathering - ANSWERthe physical breakdown or disintegration
of rocks and minerals into smaller and smaller pieces with no chemical change
Define Chemical Weathering - ANSWERdecomposition of rocks and minerals into
new minerals and substances due to the presence of water (H20), oxygen (O2), and
hydrogen ions (H+)
Role of Weathering in the Rock Cycle - ANSWERattacks any Earth materials
(minerals and rocks) that are exposed by Uplift and Erosion at/near the Earth's
surface
What is the source of energy for weathering process? - ANSWERSolar
Energy/Radiation
One way in which the water molecule promotes both chemical and mechanical
weathering - ANSWER-promotes chemical weathering because it dissolves many
substances due to the polar nature of the water molecule.
-promotes mechanical weathering because it expands by about 9% when it freezes
thus causing rocks to be broken into smaller pieces
5 mechanical weathering processes - ANSWERFrost Action or Wedging
Stress Release/Pressure Release
Salt Weathering-- Crystal Growth
Thermal Expansion and Contraction
Organic Activity or Bio-Mechanical Activity
Describe how Stress Release-Mechanical Exfoliation leads to Mechanical
Weathering and what type of landform results from Stress Release-Mechanical
Exfoliation - ANSWER-opens large fractures in ricks and allows other processes to
operate
-exfoliation domes
What is TALUS? - ANSWERcoarse, angular rock material that accumulates at the
base of a slope or cliff--results from a combination of frost wedging and rock falls
How and why does Mechanical Weathering enhance Chemical Weathering? -
ANSWERMechanical Weathering breaks rocks and minerals down into smaller and
smaller pieces, which provides more surface area for chemical weathering to take
place on (work together to break down rocks)
5 factors that influence Chemical Weathering - ANSWERClimate
, Rock Structure
Organic Activity
Time
Mineral and Rock Composition
(all other factors being equal) What global climate belt would you expect to observe
the fastest rates of Chemical Weathering? Why? - ANSWER-Tropical Climate
Zone/Belt
What are the primary substances necessary for Chemical Weathering? -
ANSWERWater, Oxygen, and Hydrogen Ions
What is the primary source of hydrogen ions? - ANSWERdissociation of carbonic
acid that forms as a result of dissolution of carbon dioxide in water
List and define the 3 Chemical Weathering Processes or Reactions. What type of
rock(s) that each process/reaction breaks down. - ANSWER-Dissolution: a Chemical
reaction whereby ions pass from a mineral into a solution; breaks down Limestone,
Dolostone, Marble, Rock Salt, and Rock Gypsum
-Hydrolysis: a Chemical Reaction in which Water dissociates into H+ (hydrogen
cation) and OH- (hydroxide anion); breaks down feldspars and micas in many types
of Igneous and Metamorphic Rocks
-Oxidation: a Chemical reaction in which oxygen as an oxidizing agent causes a loss
of electrons by an atom or ion and thus involves an increase in oxidation number;
breaks down Ferromagnesian minerals in Mafic Igneous Rocks and their
Metamorphic Equivalents.
For the following types of Chemical Weathering Reactions/Processes, what Gas is
removed from the atmosphere for each reaction/process, and what Substances are
needed for the reaction to take place? - ANSWER-Dissolution: CO2; Water and
Hydrogen Ions
-Hydrolysis: NONE; Water and Hydrogen Ions
-Oxidation: O2; Oxygen
For the following types of Chemical Weathering Reactions/Processes, what New
Products (especially insoluble residues) are the result of each type of Reaction? -
ANSWER-Dissolution: No Residue - All Soluble Ions-ultimately all material is totally
dissolved
-Hydrolysis: Insoluble Residue = Clay Minerals; some other material is dissolved
-Oxidation: Insoluble Residue = Iron Oxides (Hematite, Limonite, Goethite); some
other material is dissolved.
For Chemical Weathering list the following groups of minerals from Most Stable to
Least Stable: Assume that they are undergoing Chemical Weathering in the same
climate. - ANSWERMost to Least Stable: Quarts, Muscovite, Na-Plagioclase,
Pyroxene, Olivine
Most to Least Stable: Limonite, Clay
17. For Chemical Weathering list the following groups of Igneous and Metamorphic
Rocks from Most Stable/Most Resistant to Least Stable/Least Resistant to Chemical
