Paleonthology:
- the study of the history of the Earth
- the study of the history of the Earth
- uses the fossils (=remains of plants or animals from pre-historic times. They are found in
sedimentary rocks.) to establish the age of the rock layers
2 dating methods:
1.) relative dating method: based on the law of superposition (=youngest rock layers are ont he top of the rock sequence whereas the oldest are on the bottom.) a this method is rarely because both of internal forces (folding, faulting) often rearrange the layers!!
2.) absolute dating method: based ont he natural radioactivity of certain minerals (uranium,
thorium)
- C14 is used to determine the age of the organic matter
On the basis of the dating methods geologists have established a geological timescale which has got eras, periods and epochs:
ERAS | PERIODS |
Cenozoic (65 million years) | Quaternary --- holocene (present time) --- pleistocene (ice age) Tertiary --- pliocene --- miocene --- oligocene --- eocene |
Mesozoic (235 – 65 million years) | Cretaceous Jurassic Triassic |
Paleozoic (590 – 235 million years) | Permian Carboniferous Devonian Silurian Ordovician Cambrian |
Proterozoic (2600 million years) | --------- |
Archaeozoic (4600 million years) | ---------- |
ERAS:
Archaeozoic (ősidő):
-volcanic activity a gases a forming a palaeoatmosphere
-volcanic activity a gases a forming a palaeoatmosphere
-gradual cooling a water condensed a paleo-ocean
-continental crust formed
-rich in CO2, ammonia, nitrogen-oxide
Proterozoic (előidő):
- mountain formation a erosion a ancient shields
- mountain formation a erosion a ancient shields
- ancient life forms (bacteria, algae)
Paleozoic: - photosyntesis a ozone layer
- first land plants appeared
- Caledonian and Variscian mountain systems started to form
- formation of Gondwanaland
- all the continental cores connected a supercontinent (Pangaea) formed
- Panthalassa (+ Tethys /gulf of Panthalassa)
- formation of coal
Mesozoic:
- Triassic: Pangaea divided into Laurasia and Gondwana
- Triassic: Pangaea divided into Laurasia and Gondwana
- Tethys substituted Panthalassa
Laurasia slided to the North
Gondwana slided to the South
- Jurassic:- formation of a rift valley led to the formation of the Atlantic Ocean
that separated Eurasia from North-America and Africa from
South-America
-convergent plates a volcanic activity a Pacific
mountain system started to form
- Australia was still connected to Antarctica
- Cretaceous: - the world ocean reached its largest extention
- Eurasia separated from North-America, and Africa from
South-America
- Eurasian mountain system started to form
Fauna&flora:
Triassic: dinosaurs, first mammals appeared
Jurassic: - the main era of reptiles
- spread of ammonites (mészvázúak)
- first flowering plants
Cretaceous: by the end of the era they extincted aprobably a huge meteor impact
caused it due to which the level
of oxygen decreased on the Earth
(the depression of this caused by
this meteor still can be observed
on the Yukatan Peninsula)
- most characteristic plants are angiosperms(zárvatermők) and gymnosperms(nyitvatermők) (EZ NEM FONTOS!!!)
Cenozoic: - present location of the continents
- spread of mammals and birds
- formation of mineral oil and natural gas
- volcanism
- the end of the formation of the Eurasian and Pacific mountain system
- Atlantic and Indian Ocean formed
- climate got colder a Ice Age
- the end of the era (holocene): climate got warmer and the land was shaped by external forces + the appearance of the Homo Sapiens
(A MESOZOIC A LEGFONTOSABB, A TÖBBIRŐL CSAK A LEGLÉNYEGESEBBEKET KELL TUDNI!!!)
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