Chapter 4 A trip Through Geologic Time
4.1 Fossils Key Concepts How do fossils form? What are the different kinds of fossils? What does the fossil record tell about organisims and environments of the past?
4.1 Fossils Key Terms Fossil Trace fossil Sedimentary rock Mould Cast Petrified fossil Carbon film Trace fossil Paleontologist Scientific theory Evolution Extinct
4.1 Fossils How Fossils Form Most fossils form when living things die and are buried by sediments. The sediments slowly harden into rock and preserve the shapes of the organisms. Fossils found in rock include molds an casts, petrified fossils, carbon films, and trace fossils
4.1 Fossils How Fossils Form Molds and casts
4.1 Fossils How Fossils Form Petrified fossils
4.1 Fossils How Fossils Form Carbon films
4.1 Fossils How Fossils Form Trace fossils
4.1 Fossils How Fossils Form Preserved remains
4.2 The Relative Age of Rocks Key Concepts What is the law of superpostions? How do geologists determine the relative age of rocks? How are index fossils useful to geologists?
4.2 The Relative Age of Rocks Key Terms Absolute age Law of superposition Extrusion Intrusion Fault Unconformity Index fossil
4.2 The Relative Age of Rocks The Position of Rock Layers Law of Superposition – In horizontal sedimentary rock layers the oldest layer is at the bottom. The layers get younger and they get closer to the top.
4.2 The Relative Age of Rocks Determining Relative Age Clues from igneous rock – Extrusion - Layers where lava hardens on the surface. Intrusion – When the magma hardened inside the planet. It is always younger that the layers around it.
4.2 The Relative Age of Rocks Using Fossils to Date Rocks Index fossil is one that only appears in a specific layer of sediment.
4.3 Radioactive Dating Key Concepts What happens during radioactive decay? What can be learned from radioactive dating?
4.3 Radioactive Dating Key Terms Atom Element Radioactive decay Half-life
4.3 Radioactive Dating Radioactive Decay Atom –The smallest particle of an element. Element – A type of matter in which all the atoms are the same. During radioactive decay the atoms of one element break down to form atoms of another element.
4.3 Radioactive Dating Determining Absolute Ages Geologists use radioactive dating to determine the absolute ages of rocks. Potassium-Argon Dating Carbon-14 Dating Radioactive Dating of Rock Layers
4.4 The Geologic Time Scale Key Concepts Why is the geologic time scale used to show Earth’s history? What are the different units of the geologic time scale?
4.4 The Geologic Time Scale Key Terms Era Period
4.4 The Geologic Time Scale The Geologic Time Scale The age of the Earth is so huge that this Geologic Time Scale is used to put the span into sequence past to present. Era – The largest divisions (like seasons) Paleozoic – Mesozoic – Cenozoic Period – Divisions within Eras (like months)
4.4 The Geologic Time Scale The Geologic Time Scale Period – Divisions within Eras (like months) ERA Paleozoic = Cambrian – Ordovician – Silurian – Devonian – Carboniferous - Permian ERA Mesozoic = Triassic – Jurassic - Cretaceous ERA Cenozoic = Tertiary - Quaternary
4.4 The Geologic Time Scale The Geologic Time Scale
4.5 Early Earth Key Concepts & Terms When did the Earth form? How did Earth’s physical features develop during Precambrian Time? What were early Precambrian organisms like? KEY TERMS Comet Continental Drift
4.5 Early Earth Planet Forms Scientists hypothesize that Earth formed roughly 4.6 billion years ago.
4.5 Early Earth Earth Takes Shape Scientists believe that the planet began as a ball of dust, rock, and ice in space. Gravity pulled the mass together More mass = more gravity = more mass = more gravity until the area nearby was cleared. The ball was struck repeatedly added mass and kinetic energy heated up the mass. (NOTE: Find a video link)
4.5 Early Earth Earth’s Surface Forms During the first several hundred million years of Precambrian Time, the atmosphere, oceans, and continents began to form.
4.6 Eras of Earth’s History Key Concepts What were the major events in the Paleozoic Era? What were the major events in the Mesozoic Era? What were the major events in the Cenozioc Era>
4.6 Eras of Earth’s History Key Terms Invertebrate Vertebrate Amphibian Reptile Mass extinction Mammal
4.6 Eras of Earth’s History The Paleozoic Era The Cambrian Explosion Vertebrates arise Life Reaches Land The Carboniferous Period Mass extinction ends the Paleozoic The Supercontinent Pangaea
4.6 Eras of Earth’s History Precambrian
4.6 Eras of Earth’s History Cambrian Period
4.6 Eras of Earth’s History Ordovician Period
4.6 Eras of Earth’s History Silurian Period
4.6 Eras of Earth’s History Devonian Period
4.6 Eras of Earth’s History Caboniferous Period
4.6 Eras of Earth’s History Permian Period
4.6 Eras of Earth’s History Triassic Period
4.6 Eras of Earth’s History Jurassic Period
4.6 Eras of Earth’s History Creataceous Period
4.6 Eras of Earth’s History Tertiary Period
4.6 Eras of Earth’s History Quaternary Period