General and Field Geology Flashcards
What is the densest crust? Oceanic or Continental?
Oceanic
Where is new oceanic crust formed?
Mid ocean ridges/ spreading ridges
Where is new continental crust formed?
Subduction zones
What are 2 main features formed by convergent plate boundaries?
Oceanic - continental = subduction of oceanic plate which leads to the formation of volcanoes
Continental - continental = pile up of continental crust which causes mountain building
What is the densest layer of the earth? What physical state is it in (gas, liquid or solid?)
Inner Core, Solid
Name the 3 basic layers of the earth?
Crust
Mantle (upper and lower)
Core (upper and lower)
What physical state is the mantle in? (gas, liquid or solid)
Trick question… the upper mantle is solid whereas the lower mantle is liquid due to the higher temperatures.
What are the two types of body waves? How do you differentiate them from each other?
1- P (primary) waves: fast, pushing/ back and forth motion, can move through all layers of the earth
2- S (secondary) waves: slower, shear/ up and down motion, can’t move through solids
What is the Moho?
It separates the earth’s crust from the upper mantle
What stress regime do thrust faults form in?
Compressional stress
What is an anticline?
A convex/ up fold
What is a syncline?
A concave/ down fold
What is the most abundant mineral species in the earth’s crust?
Quartz
What is the most abundant mineral group in the earth’s crust?
Feldspars
What is viscosity?
Resistance to flow
What is density?
Compactness of a substance
How is density affected by pressure?
More pressure = more density
What angle do strike -slip faults form?
90 degree
What motion do transform plate boundaries make?
Slide past one another
What stress regime do normal faults form in?
Tensional stress
What stress regime do reverse faults form in?
Compressional stress
What angle do normal faults form?
greater than 45 degrees
What angle do reverse faults form?
greater than 45 degrees
What angle do thrust faults form?
Less than 45 degrees (almost parallel)
What is the principal of superposition?
A rock layer is older than the one above and younger than the one below it
What is the principle of horizontal originality??
Sediments are always deposited horizontally or near a horizontal position under gravity
What is the principle of lateral continuity?
Rock layers will extend continuously in all directions until they thin out, grade into different rock strata, or meet a barrier
What is the principle of cross-cutting relationships?
A rock unit or geological feature/structure that cuts or deforms another is younger than the geological feature/structure or body of rock it cuts, penetrates, or bends
What is the principle of inclusions?
Rock fragments (clasts or xenoliths) enclosed by another rock are older than the rock that surrounds it
What is the principle of faunal succession?
Sedimentary strata have diagnostic fossils and fossils assemblage that succeed each other vertically in a predictable and reliable order and can be identified over a wide horizontal distance
What is an angular unconformity?
A type of unconformity where younger upper and older rock strata lie at different angles. It separates younger flat rock strata from eroded, truncated, tilted, folded, or deformed older rock beds.
What is a nonconformity?
An unconformity between younger top sedimentary rock strata and older lower intrusive igneous or metamorphic rocks. This contact occurs where younger sedimentary rock beds overlie older eroded crystalline plutonic or metamorphic rocks.
What is a disconformity?
A buried erosional or non-depositional surface separating parallel rock strata of different ages with visible, irregular, or uneven erosional surfaces. The rock beds between the unconformity have the same orientation and discernable erosional features.
What is a paraconformity?
A type of unconformity with parallel rock beds or strata that don’t have discernable erosional features at the contact plane. It is a type of disconformity where the older and younger beds don’t have visible erosional features, making non-deposition a likely reason for its formation.
Paraconformities are the hardest to identify unless you use fossil records, and sometimes, they are known as pseudoconformities or non-depositional unconformities.
If a map scale reads 1:24,000 how many feet does 1 inch represent?
2000 feet
To solve this, take 24,000 inches divided by 12 (12 inches = 1 foot) to get 2000 feet.
What is the soil classification symbol “CL” represent?
inorganic clays of low to medium plasticity
What is the soil classification symbol “ML” represent?
inorganic silts and very fine sands
What is the soil classification symbol “OL” represent?
organic silts or organic silty clays of low plasticity
What is the soil classification symbol “CH” represent?
inorganic clays of high plasticity (FAT CLAY)
What is the soil classification symbol “MH” represent?
inorganic silts, micaceous fine sands or silty soils (ELASTIC SILTS)
What is the soil classification symbol “OH” represent?
organic clays or silts of medium or high plasticity
Using the Rule of V’s, what can be interpreted when a “V” follows the topography lines?
Horizontal bedding
Using the Rule of V’s, what can be interpreted when there is no (flat) “V” and there is a straight line cutting across valley topography?
Vertical bedding
Using the Rule of V’s, what can be interpreted when the “V” is pointing upstream?
Dip upstream
Using the Rule of V’s, what can be interpreted when the “V” is pointing downstream?
Dip downstream
What is Rippability?
The ease with which soil or rock can be excavated mechanically.
