Term 4 p2 Flashcards
(20 cards)
what is a fossil
fossils are remains of ancient life forms
what is continenal drift
the movement of continental plates apart or together over a period of time
what is diverage
one part seperating or two parts are going apart
how long did the cambrain explosion last
for 38 million years
the two major extinctions that happened
250 million years ago [90%of all species ]
65million years ago [all dinosaurs ]
what is mass extinction
when 50 % of species die in a short period of time
some evidence of the major extinction
climate change
many plants dried out
thin layer of clay
The Epoch we live in now is the …….
Holocene Epoch
three main hypothesis
asteriod of outer space
movement of continents away from each other
volcanic activity
what is the study of fossils
paleontology
what will cause the extintion in the holocence epoch era
human activity
where can you find fossils after a long period of time
in ice ,tar ,amber
How fossils form
the soft bodied organism is skin decays the the bones left are moved into salt water where the bone absorp the mineral salts which harden the bones structure to last long
where are fossils mostly found
in sedimentary rock
what is a index fossil
a fossil that is found in a large number of areas
What are the two methods to find the age of a fossil
Relative dating and Radioactive dating
What is relative dating
Tells us whether a fossil is formed before or after another fossil
What is radioactive dating
Tells us how long ago a particular fossil was formed
Relationship between the history of life and other important events
- Increase in oxygen levels
- Cooling of the earth
- Continental drift
- Theory of tectonic plates
- Volcanic activity
- Fossil evidence
Causes of the extinction of 65 MYA
- Sharp drop in temperatures
- Many plants died out
- Volcanic eruptions
