Geological TIme

The geological time scale is divided into many subdivisions. The largest subdivision is

• Eras
• Periods
• Eons
• Epochs

Which of the following is not a true geological eon, era, period or epoch?

• Cambrian
• Precambrian Time
• Jurassic
• Quaternary

The Hadean is technically not a geological period as

• There is no rock on Earth that is this old
• Dinosaurs were not present at that time
• Humans were not present at that time
• The moon had not formed at this time

Evidence on earth of solid rock older than 3.8 billion years is lacking because

• Those rocks haven't been found yet
• Dinosaurs have eaten all rocks over 3.8 billion years
• Older rocks have been lost due to erosion and plate tectonics
• They are under the sea

In the early Archaean eon life forms appeared on earth. Evidence for this are

• Micro fossils of bacteria in the form of stromatolites
• Eurkaryotic cells found trapped in amber
• Reptile footprints in sand
• Bacteria trapped in permafrost

Multicellular algae and the first animals evolved towards the end of the proterozoic eon. This was most likely due to

• Decreased oxygen levels in the atmosphere due to photosynthetic organisms
• Predators
• Genetic Drift
• Increased oxygen levels in the atmosphere due to photosynthetic organisms

At the end of the proterozoic eon, reveals evidence of a diversity of multi cellular animals - the fossils are mainly of

• Vertebrates
• Small dinosaurs
• Small soft bodied sea creatures
• Prokaryotes

The Palaeozoic era was a time of great change for the earth.

• Earth landmasses formed 3 supercontinents ( Gondwana, Laurasia and Pangaea)
• Two supercontinents Gondwand and Laurasia formed and greatly affected the climate, the land and sea environments
• Pangaea broke up
• Humans caused the formation of Pangaea

The Cambrian explosion

• Was a large volcanic eruption
• Caused the end of trilobites
• Showed a reduced diversity in fossils
• Showed a dramatic increase in the number and complexity of life in the oceans

The end of the Ordovician period (485.4 - 443.8 mya) was marked by

• A major ice age and mass extinction
• Extinction of the dinosaurs
• Jawless fish eating all the vertebrates
• Loss of all life on earth