ASBOG - General and Field Geology
Exam Questions and Answers
Law of Superposition - ANS-Younger layers of rock sit atop older layers
Law of Initial Horizontality - ANS-Layers of sedimentary rock are initially deposited flat in
layers.
relative age dating - ANS-the fossil assemblage existing within a rock specimen can be
used to determine upper and lower possible age. Gives age range. Example: 100 to 200
mya.
radiometric dating - ANS-the process of measuring the absolute age of geologic
material by measuring the concentrations of radioactive isotopes and their decay
products. Can give exact date.
paleomagnetic dating - ANS-A method for determining the age of rocks based on
properties relating to changes in the patterns of Earth's magnetism over time.
Carbon-14 or radiocarbon - ANS-dates up to 60,000 years.
Potassium-argon isotope dating - ANS-greater than 100,000 years old
Uranium-thorium dating - ANS-date carbonate materials that are younger than about
500,000 years
Rubidium-Strontium isotope dating - ANS-igneous materials over 10 million years old
Uranium-lead isotopes - ANS-date between 1 million and 4.5 billion years old
geologic time scale - ANS-
Paleozoic - ANS-first appearance of invertebrates
Mesozoic Era - ANS-appearance of reptiles
Cenozoic Era - ANS-Appearance of mammals and man
Type section - ANS-Geologic formation named based on the specific location or area
where the formation is best exposed or best represented. EX: local town or cultural
features. (formation)
, type locality - ANS-where a mineral or geologic feature is first found, described, and
best represented. (mineral or geologic feature)
Fault - ANS-Geologic fracture or fracture zone in crustal rocks along which there has
been displacement of the two sides relative to one another parallel to the fracture. The
dip of a fault (the angle of the fault relative to horiontal) can be between 0 (flat lying) and
90 (vertical) degrees. Consist of a hanging and footwall.
Vertical Fault - ANS-no distinguishable foot or hang wall since both surfaces are vertical
normal fault - ANS-A type of fault where the hanging wall slides downward; caused by
tension in the crust
Reverse Fault (thrust) - ANS-a type of fault where the hanging wall slides upward;
caused by compression in the crust
strike-slip fault - ANS-a type of fault where rocks on either side move past each other
sideways with little up or down motion
Growth Fault - ANS-A fault that forms contemporaneously with deposition in
sedimentary rock. The throw increases with depth and the sedimentary units on the
downthrown side are thicker than the corresponding units on the upthrown side
detachment fault - ANS-A low-angle normal fault associated with regional extension.
Typically in the tens of kilometer range. Usually juxtapose unmetamorphosed headwall
rocks against mildly to highly metamorphosed footwall rocks.
listric fault - ANS--similar to normal faults but the fault plane curves, the dip being
steeper near the surface, then shallower with increased depth.
-The dip may flatten into a sub-horizontal décollement, resulting in horizontal slip on a
horizontal plane.
oblique-slip fault - ANS-A fault with both strike-slip and dip-slip components.
thrust fault - ANS-Low angle reverse fault. Plane of the fault is between 0 and 45
degrees.
heave - ANS-horizontal movement along a fault
throw - ANS-vertical component of dip separation
rock strength - ANS-accessing a rocks hardness, fracturing, porosity, and the degree of
which it has been weathered.
Exam Questions and Answers
Law of Superposition - ANS-Younger layers of rock sit atop older layers
Law of Initial Horizontality - ANS-Layers of sedimentary rock are initially deposited flat in
layers.
relative age dating - ANS-the fossil assemblage existing within a rock specimen can be
used to determine upper and lower possible age. Gives age range. Example: 100 to 200
mya.
radiometric dating - ANS-the process of measuring the absolute age of geologic
material by measuring the concentrations of radioactive isotopes and their decay
products. Can give exact date.
paleomagnetic dating - ANS-A method for determining the age of rocks based on
properties relating to changes in the patterns of Earth's magnetism over time.
Carbon-14 or radiocarbon - ANS-dates up to 60,000 years.
Potassium-argon isotope dating - ANS-greater than 100,000 years old
Uranium-thorium dating - ANS-date carbonate materials that are younger than about
500,000 years
Rubidium-Strontium isotope dating - ANS-igneous materials over 10 million years old
Uranium-lead isotopes - ANS-date between 1 million and 4.5 billion years old
geologic time scale - ANS-
Paleozoic - ANS-first appearance of invertebrates
Mesozoic Era - ANS-appearance of reptiles
Cenozoic Era - ANS-Appearance of mammals and man
Type section - ANS-Geologic formation named based on the specific location or area
where the formation is best exposed or best represented. EX: local town or cultural
features. (formation)
, type locality - ANS-where a mineral or geologic feature is first found, described, and
best represented. (mineral or geologic feature)
Fault - ANS-Geologic fracture or fracture zone in crustal rocks along which there has
been displacement of the two sides relative to one another parallel to the fracture. The
dip of a fault (the angle of the fault relative to horiontal) can be between 0 (flat lying) and
90 (vertical) degrees. Consist of a hanging and footwall.
Vertical Fault - ANS-no distinguishable foot or hang wall since both surfaces are vertical
normal fault - ANS-A type of fault where the hanging wall slides downward; caused by
tension in the crust
Reverse Fault (thrust) - ANS-a type of fault where the hanging wall slides upward;
caused by compression in the crust
strike-slip fault - ANS-a type of fault where rocks on either side move past each other
sideways with little up or down motion
Growth Fault - ANS-A fault that forms contemporaneously with deposition in
sedimentary rock. The throw increases with depth and the sedimentary units on the
downthrown side are thicker than the corresponding units on the upthrown side
detachment fault - ANS-A low-angle normal fault associated with regional extension.
Typically in the tens of kilometer range. Usually juxtapose unmetamorphosed headwall
rocks against mildly to highly metamorphosed footwall rocks.
listric fault - ANS--similar to normal faults but the fault plane curves, the dip being
steeper near the surface, then shallower with increased depth.
-The dip may flatten into a sub-horizontal décollement, resulting in horizontal slip on a
horizontal plane.
oblique-slip fault - ANS-A fault with both strike-slip and dip-slip components.
thrust fault - ANS-Low angle reverse fault. Plane of the fault is between 0 and 45
degrees.
heave - ANS-horizontal movement along a fault
throw - ANS-vertical component of dip separation
rock strength - ANS-accessing a rocks hardness, fracturing, porosity, and the degree of
which it has been weathered.
