What is the Earth s time scale?

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Kelly McBride
6 years ago
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1 Earth History

Scientists developed the time scale by fossils

2 What is the Earth s time scale? The Geological time scale is a record of the life forms and geological events in Earth s history. Scientists developed the time scale by fossils world wide. Radioactive dating (like Carbon Dating) helped determine the absolute divisions in the time scale.

3 Geological time Scale (largest to smallest) Super-eon Eon Era* - 4 Period* -11 Epoch - Current Age - Current

4 Current Middle Past Q T C J T P C D S O C Question? Tough Contest Judge To Pizza Cook Deliciously So Oscar Could

5 Other Mnemonic Devices Chris Ordered Some Delicious Pizza That Just Cost Twenty Quarters Cold Oysters Seldom Develop Many Precious Pearls, Their Juices Congeal To Quickly (Parents) Can Only Sit Down Carefully; Perhaps Their Joints Can't Tolerate Quickness

6 FOUR Eras PRE-CAMBRIAN 88% of earth s history Paleozoic (ancient life) 544 million years ago lasted 300 million yrs Mesozoic (middle life) 245 million years ago lasted 180 million yrs Cenozoic (recent life) 65 million years ago continues through present day

7 Pre-Cambrian Began with the formation of the Earth 4.6 billion years ago. Accounts for 88% of whole Earth History.

8 Paleozoic Era Ancient Life Explosion of life in the oceans began during this era. Most of the continents were covered in warm, shallow seas. Invertebrates were dominate Fish emerged which led to the arrival of amphibians The early coal forming forests were also formed during this time. Carboniferous Period

9 Paleozoic Era Divided into 6 periods: Cambrian period - Age of the Trilobites Ordovician period - First fishes evolved and other species become extinct Silurian period - Land plants, insects and spiders appear

10 Devonian period - Amphibians Carboniferous period - Reptiles evolve. Where we get most of our coal/fossil fuel now. Permian period - insects and reptiles become widespread.

11 Trilobites Lived in Earth s ancient seas Extinct before the dinosaurs came into existence Cambrian Period is known as the Age of the Trilobites

12 END of the Paleozoic Era the largest mass extinction in history wiped out approximately 90% of all marine animal species and 70% of land animals. Possible causes of this Mass Extinction Event Lowering of sea levels when the continents were rejoined as Pangaea (convergent boundary) Increased volcanic activity (ash and dust) Climate changes cooler climate

13 Mesozoic Era Middle Life At the beginning of this era the continents were joined as Pangaea. Pangaea broke up around the middle of this era. Reptiles became the most abundant animals because of their ability to adapt to the drier climate of the Mesozoic Era.

14 Mesozoic Era Dinosaurs were also very active in this era. First small dinosaurs appeared in the Triassic Period. Larger and more abundant dinosaurs appeared in the Jurassic Period. Small mammals and birds also appeared during this era.

15 Mesozoic Era Divided into 3 periods: Triassic period - Turtles and crocodiles evolve and dinosaurs appear. Jurassic period - Large dinosaurs roam the world. First mammals and birds appear. Cretaceous period - Flowering plants appear, mammals become more common, dinosaurs become extinct.

16 Mesozoic Mammals

17 Mesozoic Reptiles

18 End of the Mesozoic Era This era ended with a mass extinction event about 65 million years ago. Many groups of animals, including the dinosaurs disappeared suddenly at this time. Many scientists believe that this event was caused by a comet or asteroid colliding with the Earth.

20 Cenozoic Era Recent Life Began about 65 million years ago and continues today!!!!! Climate was warm and mild. Marine animals evolved. Mammals began to increase and evolve adaptations that allowed them to live in many different environments land, air and the sea. This era is sometimes called the Age of Mammals

21 Cenozoic Era Divided into 2 periods: Tertiary period - First primates appear and become the most common. Quaternary period - Humans evolve and large mammals like woolly mammoths become extinct.

22 Today Today we are in the Holocene Epoch of the Quaternary Period of the Cenozoic Era. Which unit is the largest? Which unit is the smallest?

Earth History. What is the Earth s time scale? Geological time Scale. Pre-Cambrian. FOUR Eras

Earth History. What is the Earth s time scale? Geological time Scale. Pre-Cambrian. FOUR Eras The Earth is 4.6 billion years old! Earth History Mrs. Burkey ESS Cy Creek HS 17-18 If the Earth formed at midnight 6:00 am First life appears 10:00 pm First animals/plants on land 11:59 pm First humans