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Key Terms

This resource provides explanations of the key concepts encountered when exploring Dating the Past – the ‘basics’ that every student should understand.

  1. Geology
  2. Paleontology
  3. Fossils
  4. Igneous rock
  5. Sedimentary rock
  6. Ice ages
  7. Cores
  8. Relative dating
  9. Absolute dating
  10. Radiometric dating
  11. Geological timescale
  12. Paleo-
  1. 1. Geology

    The study of the Earth – the rocks that make it, its structure and the way it has changed over time.

  2. 2. Paleontology

    A branch of geology that uses fossils to study the history of life on Earth.

  3. 3. Fossils

    Remains of once-living organisms preserved in rocks. Includes shells and bones, often replaced by other minerals, and traces such as tracks.

  4. 4. Igneous rock

    Formed by the cooling of molten rock. Igneous rock may be volcanic (made above the surface) or plutonic (formed deep below ground).

  5. 5. Sedimentary rock

    Rock made of material derived from other rocks by weathering or by chemical deposition. Most fossils are found in sedimentary rocks.

  6. 6. Ice ages

    Times when ice sheets covered large parts of the Earth’s surface. Also called glacial periods, they occurred in cycles with warm interglacial periods in between.

  7. 7. Cores

    To study rocks or sediments hidden below ground or below the sea, geologists drill out narrow columns of material called cores.

  8. 8. Relative dating

    A technique used by geologists (and other scientists) to put material into a sequence from oldest to youngest.

  9. 9. Absolute dating

    A range of methods for providing actual dates for material, including some types of rock.

  10. 10. Radiometric dating

    Absolute dating based on measuring certain radioactive elements found in rocks. The amount they have decayed is related to how long ago the rock was formed.

  11. 11. Geological timescale

    The arrangement of Earth’s 4.6 billion year history into time divisions, based mainly on the appearance and extinction of key living organisms.

  12. 12. Paleo-

    A prefix, meaning ancient or prehistoric, which starts a number of words used by geologists. The standard spelling used by New Zealand scientists is ‘paleo’ but you might come across the spelling ‘palaeo’ used in some other countries.