Fossil/Age of Rock Notes Use the Purple book to get notes for fossils and relative age of rock notes. Write the word and definition for all of the vocab words you find in the sections. Also, write down any information that is in BOLD Fossils, page Relative Age of Rock, pages When finished complete the work sheet over Relative age of Rocks. Types of Fossils Hint: if its purple it goes in your notes Paleontologists paleontologists - Scientists who study fossils The Fossil Record The record of fossils on earth that help give evidence about the history of life on earth. Shows how groups of organisms may have changed over time This is much of what the Theory of Evolution is based on Gradual change in living things over long periods of time Fossils are NOT bone When a fossil is found in rock it is not the actual organism the organism has been replaced with minerals Types of Fossils Made of Minerals Petrified fossils Mold Cast Carbon film Trace fossils Organism Preserved remains 99% of all organisms that die do NOT become fossils 99% of all organisms that have lived on earth have become extinct Fossils give us a historical picture of what the Earth was like in the past but because fossils are very rare, there might be gaps in the historical record. Molds and Casts Mold is the hollow area the organism once took up Usually concave Ex: ice cube tray Molds and Casts Cast is the copy of the shape of an organism that would be made in a mold. Usually convex Ex: ice cubes Molds and Cast Question: Which is the mold and which is the cast? Answer: the mold is the tray, the casts are the ice cubes Preserved Remains - Jackpot! Organisms can become preserved whole when they are caught in tar, amber (tree sap), mud pits, or ice that harden around them Usually small organisms or plants Petrified Fossils Mineral replacement Pg 107, Fig 2 draw/label in notes As organism decomposes and erodes away minerals flow in to replace pieces of organism Ex: Petrified wood Carbon Film Thin film coating of carbon is left on the rock when the organism gets squished only carbon film is left behind Trace Fossils Evidence (or traces) of an organisms activity or life Ex: footprints, burrows, termites eating Index Fossils Fossils of the same short lived species that are widely distributed over the earth Help geologists match rock layers that have moved Show relative age of rock they are found in Finding the Relative Age of Rocks Questions What are the relative and absolute ages? What is the law of superposition? What are unconformities? What are faults intrusions and extrusions? How are fossils used to date rocks? The relative age of a rock is its age compared to the ages of other rocks. It is like comparing your age to someone elses The relative age does not provide its absolute age The absolute age of a rock is the number of years since the rock formed. It is difficult for geologists to determine the absolute age The law of superposition states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the one below it. Unconformity is where an old eroded surface is in contact with a new rock layer. Faults can occur only after rock layer have formed; therefore rock layers are older than the faults Igneous rocks that have formed as magma and cool underground are called intrusions Extrusion are volcanic, molten materials that cool and harden when they reach the Earths surface Types of Fossils Hint: if its purple it goes in your notes Paleontologists paleontologists - Scientists who study ___________ The Fossil Record The __________ of fossils on earth that help give evidence about the history of life on earth. Shows how groups of organisms may have ________________________________ This is much of what the Theory of Evolution is based on Gradual change in living things over long periods of time See pg. 111 Fossils are NOT bone When a fossil is found in rock it is not the actual organism the organism has been replaced with _____________ Types of Fossils Made of Minerals _____________ Organism _____________ 99% of all organisms that die do NOT become fossils 99% of all organisms that have lived on earth have become extinct Fossils give us a historical picture of what the Earth was like in the past but because fossils are very rare, there might be gaps in the historical record. Molds and Casts _____________ is the hollow area the organism once took up Usually _____________ Ex: ice cube tray Molds and Casts _____________is the copy of the shape of an organism that would be made in a mold. Usually _____________ Ex: ice cubes Molds and Cast Question: Which is the mold and which is the cast? Answer: the mold is the tray, the casts are the ice cubes _____________- Jackpot! Organisms can become preserved whole when they are caught in tar, amber (tree sap), mud pits, or ice that harden around them Usually small organisms or plants _____________ Mineral replacement Pg 107, Fig 2 draw/label in notes As organism decomposes and erodes away minerals flow in to replace pieces of organism Ex: Petrified wood _____________ Thin film coating of carbon is left on the rock when the organism gets squished only carbon film is left behind _____________ Evidence (or traces) of an organisms activity or life Ex: footprints, burrows, termites eating _____________ Fossils of the same short lived species that are widely distributed over the earth Help geologists match rock layers that have moved Show relative age of rock they are found in Finding the Relative Age of Rocks Questions What are the relative and absolute ages? What is the law of superposition? What are unconformities? What are faults intrusions and extrusions? How are fossils used to date rocks? The _____________ of a rock is its age compared to the ages of other rocks. It is like comparing your age to someone elses The relative age does not provide its absolute age The _____________of a rock is the number of years since the rock formed. It is difficult for geologists to determine the absolute age The _______________________states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the one below it. _____________ is where an old eroded surface is in contact with a new rock layer. Faults can occur only after rock layer have formed; therefore rock layers are older than the faults Igneous rocks that have formed as magma and cool underground are called _____________ _____________ are volcanic, molten materials that cool and harden when they reach the Earths surface