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Studying the Past Fossils, Relative Time and Absolute Time.

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Presentation on theme: "Studying the Past Fossils, Relative Time and Absolute Time."— Presentation transcript:

1 Studying the Past Fossils, Relative Time and Absolute Time

2 Paleontology The study of the forms of life existing in prehistoric or geologic times, as represented by the fossils of plants, animals, and other organisms. The study of the forms of life existing in prehistoric or geologic times, as represented by the fossils of plants, animals, and other organisms.

3 What do you know about fossils?

4 Fossils Fossilis is Latin for dug up Fossilis is Latin for dug up Fossils are the remains, molds or traces of organisms that died a long time ago Fossils are the remains, molds or traces of organisms that died a long time ago Fossils are usually found in sedimentary rock like sandstone, limestone or shale Fossils are usually found in sedimentary rock like sandstone, limestone or shale

5 Fossils Fossils provide evidence that different organisms lived long ago Fossils provide evidence that different organisms lived long ago Fossil organisms many times do not exist on Earth anymore Fossil organisms many times do not exist on Earth anymore They have gone extinct or they have evolved They have gone extinct or they have evolved

6 Fossils As we go through the different types of fossils look for what each type of fossil needs to form. As 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 Original Remains Replaced Remains Replaced Remains Molds and Casts Molds and Casts Trace Fossils Trace Fossils Carbonaceous Films Carbonaceous Films

8 Original Remains Very rare Very rare Most animals decay or decompose Most animals decay or decompose Examples Examples Frozen woolly mammoths Frozen woolly mammoths Insects incased in resin (amber) Insects incased in resin (amber)

9 Replaced Remains Actual remains are replaced with minerals Actual remains are replaced with minerals Many hard parts fossilize this way Many hard parts fossilize this way Teeth Bones Shells

10 Molds and Casts A replaced remain fossil may dissolve leaving behind a mold A replaced remain fossil may dissolve leaving behind a mold Later minerals may fill in the mold creating a cast of the original organism Later minerals may fill in the mold creating a cast of the original organism Click picture to see cast and mold formation

11 Trace Fossils No actual part of the organism is left No actual part of the organism is left Give information about the location of different organisms Give information about the location of different organisms Traces like Traces like Impressions Impressions Bite Marks Bite Marks Burrows Burrows Feces Feces Tracks Tracks Coprolites Coprolites

12 Carbonaceous Films An imprint or thin film is left behind An imprint or thin film is left behind Not the actual organism Not the actual organism Tissue undergo chemical changes Tissue undergo chemical changes

13 What do fossils need to form? Sediment Sediment Compaction Compaction Water Water Minerals Minerals Organism Organism TIME!!! Lots of TIME!!! TIME!!! Lots of TIME!!!

14 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 Dating Relative Dating Example: Example: On the way home I stopped for gas On the way home I stopped for gas First, I ate dinner First, I ate dinner I drove home I drove home Then I went to the store Then I went to the store Absolute Dating Absolute Dating Example I drove home at 5:35 I stopped for gas at 5:25 I ate dinner at 5:00 I went to the store at 5:15

16 Dating Past Geologic Events What is the difference between these two dating methods? What is the difference between these two dating methods? Relative Time has no actual times but can be put in order Relative Time has no actual times but can be put in order Absolute Time gives actual times Absolute Time gives actual times

17 Relative Time Puts events in a sequence without telling when they actually happened Puts events in a sequence without telling when they actually happened Does not reveal actual age but age in comparison to other events Does not reveal actual age but age in comparison to other events

18 Relative Dating The evidence is in the rocks The evidence is in the rocks Each layer represents a different place in time Each layer represents a different place in time Every layer of rock is another part of the timeline Every layer of rock is another part of the timeline

19 Uniformitarianism the present is the key to the pastthe present is the key to the past We can watch how things happen now to understand how they happened before. We can watch how things happen now to understand how they happened before.

20 Uniformitarianism James Hutton realized these processes did not happen quickly therefore the Earth must be very old. James Hutton realized these processes did not happen quickly therefore the Earth must be very old.

21 Uniformitarianism Siccar point in Scotland is where he made the observations Siccar point in Scotland is where he made the observations Came up with the idea of DEEP TIME Came up with the idea of DEEP TIME

22 Principles of Relative Dating Principles of Relative Dating The Principle of Superposition The Principle of Superposition The Principle of Cross-Cutting Relationships The Principle of Cross-Cutting Relationships Embedded Fragments Embedded Fragments

23 The Principle of Superposition Draw This… Draw This… Water

24 The Principle of Superposition The OLDEST rock is on the bottom and the YOUNGEST is on the top The OLDEST rock is on the bottom and the YOUNGEST is on the top Rocks are deposited horizontally Rocks are deposited horizontally

25 The Principle of Cross-Cutting Relationships Draw This… Draw This… Water 4

26 The Principle of Cross-Cutting Relationships An igneous intrusion is YOUNGER than the rock it intrudes An igneous intrusion is YOUNGER than the rock it intrudes A fault is YOUNGER than the rock it breaks A fault is YOUNGER than the rock it breaks

27 The Principle of Embedded Fragments Water 4

28 Rocks that are embedded in other rocks are OLDER than the rock they are found. Rocks that are embedded in other rocks are OLDER than the rock they are found.

29 Unconformity Gaps in time Gaps in time Surfaces have been eroded away Surfaces have been eroded away New rock has been laid on top New rock has been laid on top

30 Unconformity

31 Putting in all together Rock layer correlation Rock layer correlation Matching rock in one area to rocks in another Matching rock in one area to rocks in another Match characteristics Match characteristics Match index fossils Match index fossils Using fossils to tell what type of environment existed Using fossils to tell what type of environment existed

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33 Index Fossils Fossils that can be used to identify a certain rock layer Fossils that can be used to identify a certain rock layer Fossils that lived within a certain time can give the rock a relative age. See page 653 Fossils that lived within a certain time can give the rock a relative age. See page 653

34 Fossils Fossils can also give clues to the type of environment existed. Fossils can also give clues to the type of environment existed. Is there a lot of coral? Is there a lot of coral? Are there a lot of amphibians? Are there a lot of amphibians? Are there a lot of deep sea animals? Are there a lot of deep sea animals?

35 Relative Time Use the present to determine past processes Use the present to determine past processes No actual time is given No actual time is given Fossils can be used to indicate a general time Fossils can be used to indicate a general time 3 Principles 3 Principles

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