6Fossil are the preserved remains or traces of living things. They form when living things die and are buried by sediment.They are usually found in _______________ rock
73 Main Types of Fossils 2. Molds and Casts: 1. Petrified fossils: formed by replacement.Water carrying minerals replace all or part of an organism.2. Molds and Casts:Mold: hollow area in sediment in the shape of an organismCast: water carrying minerals seeps into the mold and deposits the minerals
83. Carbon films: As a buried plant or animal decays, it releases gases containing carbon. - the gases escape, leaving the carbon behind preserving the plant or animals image.
9Trace fossils: evidence that an organism was previously there Example: footprints, trails, burrows
10Why do we study fossils?1. The fossil record provides evidence about the history of life on Earth.The fossil record can tell us about past environments and climate change on Earth.The fossil record can tell us about mass extinctions
112. The fossil record shows how organisms have changed over time 2. The fossil record shows how organisms have changed over time. (evolution)It shows how organisms have gone from simple to more complex organisms
12When rocks are rearranged by bending this is known as a : A. faultB. upliftC. foldD. I don’t know
13Identify the type of fault shown in the diagram. A. normalB. reverseC. strike-slipD. I don’t know
14Identify the force which caused the pictured fault. A. tensionB. compressionC. shearD. I don’t know
15Define the following: Relative age Absolute age Law of superposition ExtrusionsIntrusionsUnconformityIndex fossil
16Age of RocksRelative age: the age a rock compared the age of surrounding rocksAbsolute age: the age of a rock since it was formedLaw of Superposition: in horizontal rock layers, the oldest is always on the bottom.
17- unconformity: a gap in the geologic record - extrusions: lava that hardens on the surface- always younger than the layer below it- intrusions: magma that hardens below ground- dike: always younger than the rock layer itcuts across- unconformity: a gap in the geologic record- missing layer(s) usually due to erosion
18-index fossil: a fossil that can be used to determine the relative age of rock layers - fossil must be widely distributed and shouldhave existed for a short period of time.Fossils record shows how life has become more complex.Example : trilobites, ammonites
19The Law of Superposition states that: A. rock layers are deposited horizontally.B. rock layers on the bottom are the oldest.C. rock layers on the top are the oldest.D. I don’t know
20By studying fossils we can find out: A. when extinct organisms livedB. what extinct organisms behaved likeC. the year they diedD. I don’t know