Life

Fossils- the remains of once-living organisms (plants/animals/bacteria/fungi)

Fossilization- remains of the dead organism were covered by sediment and preserved

Fossilization is extremely rare.

A person who studies fossils is a Palaeontologist.

A person who studies rocks, soils, and minerals are a Geologist.

Earth is 4,600,000,000

Geologic Time Scale= divides earth’s history into intervals of time defined by major events or changes

Categories are divided into the following:

  • Eon- hundreds of millions/billions of years
  • Era- tens of millions of years
  • Period- millions of years
  • Epoch- tens of thousands of years
  • Age- hundreds to thousands of years

We are in the…

  • Phanerozoic Eon
  • Cenozoic Era
  • Quarternary Period
  • Holocene Epoch
  • Meghalayan Age

7 TYPES OF FOSSILS

~permineralized fossil- the bones or tree have become rock

~carbonized fossil- only the carbon remains and leaves a film behind

~frozen remains- the whole organism is frozen including the organs

~cast and mold fossils- the impression made is called the mold and when minerals/sediment fill it in, it is called a cast

~amber fossil- the plant or animal is stuck in tree sap- over time the sap hardens into amber and is preserved

~tar pit fossil- organism gets stuck in a sticky tar- the tar preserves the bones

~trace fossil- a record of the activity of the animal- tracks, nests, burrows, scratch marks, etc.

1-6 are body fossils

Uniformitarianism- geologic events and phenomena that occur today, also happened in the past and will happen in the future

Ex: earthquake, volcano, tsunami, mud/landslides, erosion, weathering, plate tectonics

Law of Superposition- states that in a sequence of undisturbed rocks, the oldest layers are at the BOTTOM and the youngest are at the TOP

Relative Age- relates to whether one layer is older than another

Absolute Age- actual age

Radioactive decay- unstable particles in living things change into stable particles

Half-life- the amount of time needed for half of a sample of a radioactive substance to decay

Radiometric dating- the method of finding the absolute age of rock based on comparing the amounts of stable and unstable particles

Extinction- when all the members of a species die out

Fossil Record- a collection of all known fossils and their placement in order from most recent

Mass Extinction- large numbers of species die out in different parts of Earth during a relatively short period of time

REASONS FOR MASS EXTINCTION

  • Natural disasters

  • Meteor strike

  • Climate change

  • Low oxygen levels in oceans

  • Diseases

  • Solar events

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