HISTORICAL GEOLOGY

• studies thr earth's origin and evolution through time

  historical geology
• three themes of historical geology

  time

  plate tectonics

  evolution of life
• tells how old something is in relation to other objects, but cannot provide a year or specific date of use

  relative dating
• date the time of crystallization of new minerals in a rock using radioactive isotopes


  absolute dating
• he period of time it takes for of a particular radioactive substance to decay

  half-life
• what can be determined when measuring the amount of original parent and new daughter isotope?

  age of rock
• mostly used element fo absolute dating

  uranium 238 - lead 206 - zircon
• elements used to date fossils

  carbon 14 - nitrogen 14
• grand unifying theory of geology

  plate tectonics
• fossil evidences showed that life from the past is very different from what live sin the present
• natural selection were thought by darwin and wallace
• any recognizable evidence of pre-existing life

  fossils
• these are fossilized faeces


  coprolite
• principle where the formation of strata and rock layers are acknowledged

  steno's principles
• who proposed steno's principles

  nicholar steno or niels stenson
• peinciples that govern the way sedimentary rocks are deposited and layered

  steno's principles
• in sequence of strata, any stratum younger than the strata on which it rests, is older than the strata that rests upon it

  law of superstition
• strata are deposited horizontally

  law of original horizontality
• strata are deposited horizontally except for marginal basins where strata slope are sligthly downwards
• strata can be assumed to have continued laterally far from where they presently end

  law of lateral continuity
• things that cross-cut layers probably postdate dame

  law of cross-cutting relationship
• break in conformity in a rock sequencecaused by erosion

  unconformity
• erosional contacts that are parallel from the upper and lower units

  disconformity
• contact that separates a younger sedimentarhy rock from older underlying rocks that are tilted or defomed

  angular unconformity
• contact that separates a younger sedimentary rock from a metamorphic or intrusive igenous rock

  nonconformity
• 2 principles of stratigraphy

  principle of fossil succession

  principle of inclusion
• different fossil species always appear and disappear in the same order

  principle of fossil succession
• any rock fragment that are included in the rock must be older than the rock in which they are included

  principle of inclusion