4Fossils Fossilis is Latin for “dug up” Fossils are the remains, molds or traces of organisms that died a long time agoFossils are usually found in sedimentary rock like sandstone, limestone or shale
5FossilsFossils provide evidence that different organisms lived long agoFossil organisms many times do not exist on Earth anymoreThey have gone extinct or they have evolved
6FossilsAs we go through the different types of fossils look for what each type of fossil needs to form.
75 Main Types of Fossils Original Remains Replaced Remains Molds and CastsTrace FossilsCarbonaceous Films
8Original Remains Very rare Examples Most animals decay or decompose Frozen woolly mammothsInsects incased in resin (amber)
9Replaced Remains Actual remains are replaced with minerals Many hard parts fossilize this wayTeethBonesShells
10Molds and CastsA replaced remain fossil may dissolve leaving behind a moldLater minerals may fill in the mold creating a cast of the original organismClick picture to see cast and mold formation
11Trace Fossils Coprolites Tracks No actual part of the organism is left Give information about the location of different organismsTraces likeImpressionsBite MarksBurrowsFecesCoprolitesTracks
12Carbonaceous Films An imprint or thin film is left behind Not the actual organismTissue undergo chemical changes
13What do fossils need to form? SedimentCompactionWaterMineralsOrganismTIME!!! Lots of TIME!!!
14Fossil Concept Map 1. Write in the 5 fossil types 2 Fossil Concept Map 1. Write in the 5 fossil types 2. Write in a few details about each fossil type
15Dating Past Geologic Events Relative DatingExample:On the way home I stopped for gasFirst, I ate dinnerI drove homeThen I went to the storeAbsolute DatingExampleI drove home at 5:35I stopped for gas at 5:25I ate dinner at 5:00I went to the store at 5:15
16Dating Past Geologic Events What is the difference between these two dating methods?Relative Time has no actual times but can be put in orderAbsolute Time gives actual times
17Relative TimePuts events in a sequence without telling when they actually happenedDoes not reveal actual age but age in comparison to other events
18Relative Dating The evidence is in the rocks Each layer represents a different place in timeEvery layer of rock is another part of the timeline
19Uniformitarianism “the present is the key to the past” We can watch how things happen now to understand how they happened before.
20UniformitarianismJames Hutton realized these processes did not happen quickly therefore the Earth must be very old.
21UniformitarianismSiccar point in Scotland is where he made the observationsCame up with the idea of DEEP TIME
22Principles of Relative Dating The Principle of SuperpositionThe Principle of Cross-Cutting RelationshipsEmbedded Fragments
23The Principle of Superposition Draw This…Water321
24The Principle of Superposition The OLDEST rock is on the bottom and the YOUNGEST is on the topRocks are deposited horizontally
25The Principle of Cross-Cutting Relationships Draw This…Water4213
26The Principle of Cross-Cutting Relationships An igneous intrusion is YOUNGER than the rock it intrudesA fault is YOUNGER than the rock it breaks