4 Fossils 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
5 FossilsFossils provide evidence that different organisms lived long agoFossil organisms many times do not exist on Earth anymoreThey have gone extinct or they have evolved
6 FossilsAs we go through the different types of fossils look for what each type of fossil needs to form.
7 5 Main Types of Fossils Original Remains Replaced Remains Molds and CastsTrace FossilsCarbonaceous Films
8 Original Remains Very rare Examples Most animals decay or decompose Frozen woolly mammothsInsects incased in resin (amber)
9 Replaced Remains Actual remains are replaced with minerals Many hard parts fossilize this wayTeethBonesShells
10 Molds 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
11 Trace Fossils Coprolites Tracks No actual part of the organism is left Give information about the location of different organismsTraces likeImpressionsBite MarksBurrowsFecesCoprolitesTracks
12 Carbonaceous Films An imprint or thin film is left behind Not the actual organismTissue undergo chemical changes
13 What do fossils need to form? SedimentCompactionWaterMineralsOrganismTIME!!! Lots of TIME!!!
14 Fossil 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
15 Dating 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
16 Dating 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
17 Relative TimePuts events in a sequence without telling when they actually happenedDoes not reveal actual age but age in comparison to other events
18 Relative Dating The evidence is in the rocks Each layer represents a different place in timeEvery layer of rock is another part of the timeline
19 Uniformitarianism “the present is the key to the past” We can watch how things happen now to understand how they happened before.
20 UniformitarianismJames Hutton realized these processes did not happen quickly therefore the Earth must be very old.
21 UniformitarianismSiccar point in Scotland is where he made the observationsCame up with the idea of DEEP TIME
22 Principles of Relative Dating The Principle of SuperpositionThe Principle of Cross-Cutting RelationshipsEmbedded Fragments
23 The Principle of Superposition Draw This…Water321
24 The Principle of Superposition The OLDEST rock is on the bottom and the YOUNGEST is on the topRocks are deposited horizontally
25 The Principle of Cross-Cutting Relationships Draw This…Water4213
26 The Principle of Cross-Cutting Relationships An igneous intrusion is YOUNGER than the rock it intrudesA fault is YOUNGER than the rock it breaks