L7 | STRATIGRAPHY

• STRATIGRAPHY

  • deals with the study of any layered (stratified) rock, but primarily with sedimentary rocks and their;
  • composition 
  • origin 
  • age relationships 
  • geographic extent
• STRATIFICATION

  • general term for layering in sedimentary rocks.
• LAMINATION

  • layering in sedimentary rocks, which are less than 1 cm thick.
• BEDS

  • layering in sedimentary rocks, which are greater than 1 cm thick.
• SEDIMENTARY PROCESSES:

  1. WEATHERING
  2. EROSION
  3. TRANSPORT
  4. DEPOSITION
  5. DIAGENESIS
• WEATHERING

  • The physical and chemical breakdown of rocks to form sediments
• EROSION

  • In-situ removal of sediments from their sources
• TRANSPORT

  • The movement of sediments using a medium such as water or wind
• DEPOSITION

  • The settling of sediments due to the decrease in energy of the medium
• DIAGENESIS

  • The lithification of sediments to form sedimentary rock ages that are recorded in rocks.
• RELATIVE DATING

  • Determining how old something is compared to something else. 
  • Use words like "older" or "younger" instead of exact numbers.
• PRINCIPLES OF STRATIGRAPHY

  1. PRINCIPLE OF HORIZONTALITY
  2. PRINCIPLE OF LATERAL CONTINUITY
  3. PRINCIPLE OF SUPERPOSITION
  4. PRINCIPLE OF FAUNAL SUCCESSION
  5. PRINCIPLE OF INCLUSION
  6. PRINCIPLE OF CROSS CUTTING RELATIONSHIPS
  7. PRINCIPLE OF UNCONFORMITIES
• PRINCIPLE ORIGINAL HORIZONTALITY

  • deposited sediments will form horizontally
• PRINCIPLE OF LATERAL CONTINUITY

  • rock extend laterally in all directions
• PRINCIPLE OF SUPERPOSITION

  • bottom layer = oldest, top layer = youngest
• PRINCIPLE OF FAUNAL SUCCESSION

  • rocks are the same age if they have the same kinds of fossils
• PRINCIPLE OF INCLUSION

  • inclusions in rock are older than the rock containing it
• PRINCIPLE OF FAUNAL SUCCESSION

  • intrusion that cuts through is younger than the rock its cuts through
• UNCONFORMITY

  • surface of non-deposition or erosion. 
• TYPES OF UNCONFORMITY

  1. ANGULAR CONFORMITY
  2. DISCONFORMITY
  3. NONCONFORMITY
  4. PARACONFORMITY
• ANGULAR CONFORMITY

  • tilted strata overlain by more horizontal and younger strata
• DISCONFORMITY

  • evidences of erosive agents on the surface
  • represents time of minimum deposition
• NONCONFORMITY

  • younger igneous rocks intrude through older rocks
• ABSOLUTE DATING

  • determining the numerical age of materials using radioactive isotopes.
  • Radioactive isotopes a variants of the same element but with different mass number.
• PARACONFORMITY

  • most difficult unconformity to identify
  • absence of horizon or strata based on fossil assemblage. 
  • represents a period of non-deposition.