Geological Time Scale Flashcards
Two types of dating
- chronostratic
- chronometric
Chronostratic
- relative time
- time split into levels
- 3 bones 10 ft apart -> deepest one is oldest
- earth is in layers
Chronometric
- absolute time
- earth is 4.5 billion years old (measured)
- numerical ages
- radioisotopes
- carbon dating
Different packets of time
Eon
Era
Period
Epoch
Eons
Archean eon (earth began) Proterozoic eon (single celled organisms) Phanerozoic eon (stuff happened (land + O2))
Phanerozoic eon
- Paleozoic era (543 mya) (invertebrates)
- Mesozoic era (248 mya) (reptiles)
- Cenozoic era (65 mya) (mammals)
Hadean eon (when + geology)
4600 mya
- molten/liquid earth (hell)
- vaalbara (1st supercontinent) (only land)
Archean eon (when + geology + fossils)
4-2.5bya (?)
- formation of earth’s crust
- atmosphere of CH4, NH3, CO2
- volcanic activity
- protocontinents
- 1st fossils (rocks)
- metamorphic/igneous rocks
- bacteria microfossils
- salty ocean
Proterozoic eon (when + geology + fossils)
2500-570mya
- 2 supercontinents
- oxygen from stromatolites
- ice sheets (1st glaciers) (reached equator)
- microfossils from 1 billion year old bitter springs (Australia)
- snowball earth
Cambrian period (when)
540-485mya
Ordovician period (when + geology)
490-470mya
- north of tropics is almost entirely ocean
- limestone + dolomite
Silurian period (when + geology)
- 7-416mya
- glaciers
- rise in sea levels
Devonian period (when + geology + fossils)
416-358mya
- euramerica + Gondwana
- Appalachian mountains
- fossils (teeth/fish + plants)
Carboniferous period
Mississippian
Pennsylvanian
Mississippian period (when)
354mya
Upper Carboniferous
Pennsylvanian (when)
323mya
Lower Carboniferous
-name from coal
Permian period (when + geology)
299-251mya
- glaciation (beginning)
- hot + dry (end)
- pangea formed
Triassic period (when + geology + fossils)
251-199mya
- Pangea began separating
- warm + dry
- no polar ice caps
- desert
- mud stone preserved marine reptiles
- sand dunes + evaporites
Jurassic period (when + geology + fossils)
199mya
- soil deposits + oil shales
- tectonic activity formed mountain ranges
- limestone
- plants -> sedimentary rocks
Cretaceous period (when + geology + fossils)
145-166mya
- went from 18% land to 28% land
- warm + humid
- lots of volcanic activity
- high sea levels
- evaporites (proof of climate change)
- longest period
Paleogene period (when + geology)
65-23mya
- continents moved to modern positions
- tropical is cooler
- sea levels down
Neogene period (when + geology + fossils)
23-2.6mya
- continents crashed
- stellar sea cow skull
- neogene = new born
Pleistocene epoch (when + geology + fossils)
- 6mya-11700 years ago
- Ice age
- complete/almost complete skeletons (no time to decompose)
Holocene epoch (when + geology)
- 12000 years ago-now
- tundra (forest)
- bye glaciers
Hadean eon (life)
None
Archean eon (life)
Unicellular
Cyanobacteria
Stromatolites
Prokaryotes
Proterozoic eon (life)
No changes from archean eon
Algae
Single-celled organisms
Eukaryotes (nucleus)
Cambrian period (life)
Hunting techniques
Claws
Underground
Cambrian explosion
Ordovician period (life)
Adaptive
Primitive fish
Red/green algae
Cephalopods
Silurian period (life)
Spread of jawless fish
Freshwater fish
First plants/fungi
Devonian period (life)
Fish
Coral
Insects/spiders
Plants with seeds + roots (forests)
Mississippian period (life)
Sharks Amphibians Crinoids Seed ferns Conifers
Pennsylvanian period (life)
Reptiles
Land vertebrates
Freshwater
Spore bearing plants
Permian period (life)
Terrestrial plants Reptile lineages Reefs Coral + sponge species Swamp forests Gymnosperms
Triassic period (life)
Fewer evolutionary advances Ferns Considers Cycads Coelophysis Plateosaurus First dinosaurs First mammals
Jurassic period (life)
Invertebrates -insects -reefs Vertebrates -dinosaurs -birds -fish Plants -jungles -podocarps
Cretaceous period (life)
Dinosaurs
Flowers
Paleocene period (life)
Lower temp killed unicellular organisms First whales First horses Birds Grass
Neogene period (life)
Grass
Deciduous
Early primates
Pleistocene epoch (life)
Large mammals -wooly mammoth -mastodon Large plants -big seeds
Holocene epoch (life)
Mammals die
Humans
When were the extinctions (6)
Beginning of Ordovician End of Ordovician End of Devonian End of Permian End of Cretaceous Now
