geologic time scale
DESCRIPTION
Geologic Time Scale. Chapter 2, Section 3 – Unit A Science 8 Messana. EONS – largest division of time. 1. Hadean 2. Archean 3. Proterozoic 4. Phanerozoic #1-3 make up Precambrian Time Eons -> Eras -> Periods -> Epochs Change in name is due major geologic or climatic events !!. - PowerPoint PPT PresentationTRANSCRIPT
1. Hadean 2. Archean 3. Proterozoic 4. Phanerozoic
#1-3 make up Precambrian Time
Eons -> Eras -> Periods -> Epochs
Change in name is due major geologic or climatic events!!
90% of Earth’s history Lasted nearly 4 billion years of Earth’s
4.6 billion years Volcanic ash & dust ->clouds formed -
>rain Single-celled micro-organisms in ocean at
end No animals! No plants!
544 million years ago – present Explosion of Life! 3 Eras:
◦ Paleozoic Era – “Age of Amphibians”
◦ Mesozoic Era – “Age of Dinosaurs”
◦ Cenozoic Era – “Age of Mammals”
544 mya – 248 mya All life in ocean until end Fish developed Reptiles, Insects, Ferns developed – moving
life onto land at end Ends with a Mass Extinction (from a
meteor strike?)– kills 90% of all ocean species
248 mya – 65 mya Dinosaurs rule! Small mammals, birds, flowering plants Ends with Mass Extinction due to meteor
strike off Mexico ->dust cloud blocked sunlight, killed plant life and affected food chain
65 mya – Present
Large warm-blooded mammals, modern birds, flowering plants
Animals developed migration techniques Tertiary Period Quaternary Period = last 2 million yrs
◦ Ice ages
◦ 1st modern human fossils = 100,000 yrs old◦ Humans are 7 seconds of 12 hour clock!!