GTS and Relative Absolute Dating

Radiomentric Dating

finding the absolute age of a sample by determining the relative amount of radioactive parent isotope and a stable daughter isotope.

Index Fossils show up in

just a few layers

Half-life

length of time required for half of the radioactive atoms in a sample to decay

Carbonized Fossil

Forms when organisms or parts, like leaves, stems, flowers, fish, are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock.

Index fossils are

Found over a wide area and existed for a short period of time

What classify a fossil as an index fossil?

If the organism lived for a short period of time and if it covered a wide range of areas on Ea

Relative Ages of Rock layers can be determined by them

Index Fossils

The Law of Superposition states that:

Lower sedimentary layers are older than higher sedimentary layers

What era are the dinosaurs in?

Mesozoic Era

Relative Dating

Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock

What Era were Insects?

Paleozoic Era

What era are Reptiles in?

Paleozoic Era

Daughter Isotopes

Parent isotopes when broken down.

What era are Jellyfish in?

Precambrian Era

Fossils

Preserved remains of once-living organisms

cross-cutting relationships

Principle stating that a fault or intrusion is younger than the rock it cuts across.

What are the two things that are used to help determine the relative age?

Relative age can be determined using index fossils and rock layers.

What method do scientists use to find the absolute age of a rock?

Scientists use radioactive dating with Carbon-14 to find the absolute age of rocks.

Rock used to find relative age of rocks

Sedimentary

Rock where fossils are stored

Sedimentary

Law of Uniformitarianism

The Earth's movement of lithospheric plates and changes in the climate, are all similar to processes that have occurred generations ago. The idea that these processes and natural laws applied both eras ago as well as in present day

What is a relative age?

The age of a rock compared to the ages of other rocks

The fossil record shows

The fossil record gives us important information about past life and environments on Earth.

What can we gain from fossils?

We can get insight to the different climates that were on Earth at different times, evidence of the different changing species as well as the how Earth's continents continuously change

Preserved Fossil

a fossil that forms when the organisms or parts of organisms are prevented from decaying by being trapped in ice, tar, or amber. Example: Mosquito in Amber

Precambrian Era

Earth's first era that began 4.6 billion years ago that includes creation of the Sun, Earth, the atmosphere, oceans and life

Earth's estimated age

4.6 billion years

Trace Fossil

A footprint, trail, burrow of an animal rather than of the animal itself

Petrified Fossil

A fossil formed when minerals replace all or part of an organism

What is the geologic time scale?

A record of the geologic events and life forms in Earth's history.

Absolute Dating

A technique used to determine the actual age of a fossil; Gives the most details about the age of something.

Isotope

An element with a different number of neutrons

What major event occurred after each era in order for a new era to begin?

Between each Geologic era there was a mass extinction of certain species

What era do we live in?

Cenozoic Era

radioactive isotope

decays at a certain, constant rate.

uranium dating

much longer half life of 4.5 billion years.

Organic

of, relating to, or derived from living matter.