1 / 13

Fossils & The Geologic Time Scale

Explore the world of fossils, learn how they are preserved, and delve into the Geologic Time Scale. Discover petrified, mold, trace, body, and cast fossils. Understand relative and absolute dating methods and journey through the Earth's 4.6 billion-year history.

lharrington
Download Presentation

Fossils & The Geologic Time Scale

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fossils & The Geologic Time Scale

  2. Fossils • Preserved remains or traces of an organism that lived in the past. • Fossils are formed when organisms die and are buried in sediment. Eventually the sediment builds up and hardens to become sedimentary rock.

  3. Kinds of fossils • Petrified - when minerals replace the remains and they become rock • Mold - when the shell remains and the contents dissolve (hollow) • Cast - when the mold becomes filled with minerals that are not a part of the original organism • Body - when the remains of the actual organisms have become mineralized • Trace - when the track, trail, burrow,or other structure produced by a living organism has been preserved in sedimentary rock

  4. PETRIFIED MOLD TRACE BODY CAST

  5. Sometimes whole animals become preserved intact, but this is very rare. If an organism is surrounded by ice or tar they might be discovered looking much the same as they did when they died. AETOSAUR FOUND IN THE NATIONAL PETRIFIED FOREST

  6. Relative Dating Relative dating: looks at where the fossil is located to determine its age relative to other fossils. This only works if the area has been undisturbed.

  7. Absolute Dating • By determining the age of the radioactive element, scientists can calculate the age of the fossil buried nearby. • Uses radioactive elements near the fossils to determine the actual age of the fossils. The absolute age of fossils is estimated by dating associated igneous rock and lava flows.

  8. Fossil Record • The dating of all fossils is included in the Geological Time Scale. This scale divides the time that the earth has existed into 4 eras. • Eras are then divided into periods based on common events in that time period.

  9. Pre-Cambrian • Began with the formation of the Earth 4.6 billion years ago. • Bacteria appeared 3.5 billion years ago, followed by algae and fungi.

  10. Paleozoic Era • Divided into 6 periods: • Cambrian period - Sponges, snails, clams and worms evolve • Ordovician period - First fishes evolved and other species become extinct • Silurian period - Land plants, insects and spiders appear

  11. Devonian period - Amphibians evolve and cone-bearing plants start to appear. • Carboniferous period - Tropical forests appear and reptiles evolve. • Permian period - Seed plants become common and insects and reptiles become widespread. Sea animals and some amphibians begin to disappear.

  12. 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.

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

More Related