Chapter 2 Basic Geology

Question 1

2 ways to relate time in Geology

Answer 1

1. Relative Age
   Placing geological events in sequence based in their position in geological record
   Known order of events but not the date
2. Absolute Age
   Placing a specific number of years for a geological event or rock sample
   Known dates

Question 2

7 logical rules to establish relative sequences of events

Answer 2

1. Principles of Superposition
2. Principles of horizontality
3. Principles of lateral continuity
4. Principles of cross-cutting relationship
5. Principles of inclusions
6. Principles of baked/chilled contacts
7. Fossils succesion

Question 3

What are the Steno’s Law of Stratigraphy

Answer 3

1. Law of Superposition
2. Law of Horizontality
3. Law of Cross Cutting relationship
4. Law of Lateral Continuity

Question 4

Steno’s Law of Stratigraphy

Answer 4

1. Law of Superposition
   -Younger layers of rock sits on top of older layers of rock
2. Law of Horizontality
   -Layers of sedimentary rock will originally deposited flat
3. Law of Cross Cutting Relationship
   -Rock layers A B and C must be older than the intrusion D that disturbs them
4. Law of Lateral Continuity
   -Layers of rock are continues until they encounter other said bodies that block their deposition

Question 5

3 types of Unconformity (AU, NC, DC)

Answer 5

1. Angular Unconformity (D-F-E-AC)
   -The rocks above and below the unconformity have different orientations
   - It shows that there was a period of Deformation, Folding, Erosion and then renewed deposition
   -Easiest to be recognized as the units are at an angle truncated with the units above them
   -Indicates a long period of rock deposition & Erosion
2. Nonconformity (Depo & Intru - Uplift & Ero - Subsidence & Depo)
   -Rocks in a horizontal manner were eroded to igneous bedrock
   -It shows there was a period of deposition & erosion and then renewed deposition
   -Represents the greatest amount of time left out of the geological rock record
3. Disconformity (D-U-E-S-D)
   -A surface of erosion or non-deposition between parallel sedimentary rock beds of different ages
   -Indicates uplifting to sea level, erosion & lowering below sea level again

Question 6

3 principal types of Plate Boundaries

Answer 6

1. Divergent plate boundaries
   -where plates move apart from each other
   -allowing magma to come out from earth’s mantle and solidify as new crust
   -mostly lie beneath the oceans, forming ridge/mountains
   -example: Mid Atlantic Ridge (MAR)
2. Convergent plate boundaries
   -where plates approach each other and crust is consumed
   -example: The Pacific Ring of Fire (TPROF)
3. Transform plate boundaries
   -where plates slip past each other side to side and crust is preserved
   -mainly found on the ocean floor, where they offset mid ocean ridges and enable the ocean to spread at different rates
   -example: San Andreas Fault (SAF)

Question 7

4 criteria to be a Mineral

Answer 7

1. Solid
2. Naturally formed
3. Unique & specific chemical composition
4. Have crystalline structure

Question 8

What are the 7 physical properties of Mineral?

Answer 8

1. Colour
   -caused by a tiny amount of impurities
2. Crystal form
   -outward expression of the orderly arrangement of atoms
3. Density
   -a measure of how heavy an object is for a given volume
   -depending on chemical composition, type of bonding & crystal structure
4. Fracture/Cleavage
   -is how a mineral breaks
5. Hardness
   -measured using the Moh’s scale of hardness, which compares the hardness of different mineral
6. Luster
   -is how reflective a mineral is - metallic/non metallic
7. Streak

Question 9

Mohs Hardness Scale

Answer 9

T G C F A O Q T C D

1 Talc
2 Gypsum
- fingernail
3 Calcite
4 Fluorite
5 Apatite
- pocket knife
- window glass
6 Orthoclase
- steel file
7 Quartz
8 Topaz
9 Corundum
10 Diamond