Geological timescale

• What is the geological scale?

  Periods of time divided according to the rock types and sort of fossils found.
• How have scientists divided the history of the Earth?

  According to the rock types and sort of fossils found in each period.
• What does the geological timescale help define?

  The major stages in the history of life on Earth as shown by fossils.
• What do palaeontologists use the geological timescale for?

  To date and compare the age of fossils.
• What are the long periods of time in the geological timescale called?

  Eras.
• What are the main eras of the geological timescale?

  The Palaeozoic era, Mesozoic era, and Cenozoic era.
• What is the difference between an era and a period in the geological timescale?

  • An era is a very long time span covering millions of years.
  • A period is a shorter timespan that forms part of an era with distinctive kinds of life.
• What is the time span of the Permian period characterized by?

  Reptiles were abundant and the first mammals appeared.
• What are the key periods and their characteristics in the geological timescale?

  • Cenozoic: Recent life, modern humans.
  • Mesozoic: Middle life, dinosaurs and ammonites abundant.
  • Palaeozoic: Ancient life, first fish and land animals.
• What does the term "Precambrian" refer to in the geological timescale?

  It refers to the beginning of geological time before the Cambrian period.
• How does the geological timescale reflect the evolution of life on Earth?


  It shows the development of different life forms through various periods and eras.
• What is the significance of the first fish in the geological timescale?

  It marks the beginning of complex life in the oceans.
• What type of life existed during the Archaean era?


  Very simple sea plants (algae) and worms.
• What does the term "Cenozoic" refer to in the geological timescale?

  It refers to the era of recent life, including modern humans.
• What major event is associated with the extinction of dinosaurs in the geological timescale?

  The extinction of dinosaurs and ammonites, leading to the rise of mammals and flowering plants.
• How do the characteristics of life change from the Cambrian to the Cenozoic era?


  Life evolves from simple sea creatures to complex mammals and flowering plants.