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Presentation on theme: "WHAT’S IN THE ROCKS!"— Presentation transcript:


2 Bell Ringer If you were to put the following events in to a time sequence of first to last, how would you do it? What else would you add? Go to school Wake up Eat lunch Put clothes on

3 State Performance Indicators
SPI Compare fossils found in sedimentary rock to determine their relative age TOC: Geologic History Notes

4 Objectives Describe the process of relative dating to determine the age of rocks Apply geologic principles by using fossils to date sedimentary rocks Compare and Contrast different types of fossils in sedimentary rock to determine their relative age

5 Sedimentary Rock Sedimentary rocks cover 75% of the Earth’s land area.
Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock. Fossils are found in sedimentary layers.

6 Plastiglomerate Example of a sedimentary rock
Now researchers have discovered an unexpected way that some plastic waste is persisting: as a new type of stone. Fossils are found in sedimentary layers. Researchers have collected samples of plastiglomerate rock material from the polluted Kamilo Beach in Hawaii

7 Relative Dating Scientists use different methods to determine the age of objects in sedimentary rocks. One method, Relative dating, examines a fossil’s position within rock layers to estimate its age. One way to measure geologic event: Relative dating (fossils, structure, cross-cutting relationships): how old a rock is compared to surrounding rocks Absolute dating (isotopic, tree rings, etc): actual number of years since the rock was formed

8 The bottom layers of rock are usually the oldest, and the top layers are usually the youngest.
Scientists can use the order of rock layers to determine the relative age of objects within the layers. The geologic processes that occurring today have been occurring since Earth formed.

9 Discuss with elbow partner which layer is the oldest in this rock column and which is the youngest. Identify the type of rock in the oldest and youngest layers. Which is the biggest fossil in the rock column? Is the fossil young or old relative to the other fossils in the rock column?

10 The Geologic Column To make relative dating easier, geologists combine data from all of the known rock sequences around the world.

11 From this information, geologists created the geologic column — an ideal sequence of rock layers that contains all of the known fossils and rock formations on Earth, arranging layers from oldest to youngest.


13 Palaeontology Palaeontology is the science involved with the study of past life. Scientists who study past life are called palaeontologists. Palaeontologists collect data by studying fossils.

14 Dinos ‘quickly’ shrunk into birds
Bet you didn’t know! lert! Dinos ‘quickly’ shrunk into birds Paleontologists researched a new analysis of bones, feathers and teeth from 120 dinosaur species suggest a string of adaptive changes and shrinkages that led to birds!

15 A fish out of water! Future Fossil News Alert
weird but true ! Weird but true! A fish out of water! Future Fossil News Alert Recently, this fish, a Senegal bichirs can walk – and breathe on land!

16 Section 2 Looking at Fossils

17 The remains or physical evidence of an organism preserved by geologic processes is called a Fossil.

18 Fossils in rocks happen when organisms die, the fleshy parts decompose and are buried quickly in sedimentary rocks. The hard parts are left to become fossils.

19 Fossils in Amber occurs when insects get stuck in tree sap that hardens quickly.

20 Petrification is the process in which minerals replace an organisms tissues.
One form of petrification is called permineralization, which is the process in which minerals filling pore spaces of an organism’s tissues.

21 Frozen fossils occur when animals are frozen in ice and die
Frozen fossils occur when animals are frozen in ice and die. We find them 1000s of years later when it thaws. Fossils in Asphalt occurs when animals are preserved in thick, sticky pools of asphalt. Asphalt wells up and forms thick, sticky pools at Earth's surface. Example, Los Angeles

22 Trace fossils are any naturally preserved evidence of an animal’s activity.
Three types: Track- footprint Burrows- shelters made by animals Coprolites- preserved animal dung

23 Discuss with your elbow partner discuss analyze why are tracks and coprolites considered trace fossils? Burrow They are evidence of animal activity rather than fossilized organisms. Coprolite

24 Some fossils do not contain any original material of the original organism. Molds form when sediments cover the organism, such as shell, and the hard part is alter removed by weathering or erosion.

25 A cast is an object that is created when sediment fills a mold and becomes rock.
Compare and contrast a mold and a cast.

26 History of Changing Organisms
Scientists study the relationships between fossils to interpret how life has changed over time. Since the fossil record is incomplete, palaeontologists look for similarities between fossils over time to try to track change.

27 Using Fossils to Date Rocks
Scientists have found that particular types of fossils appear only in certain layers of rock.

28 By dating rock layers above and below these fossils, scientists can determine the time span in which the organism lived. If the organism lived for a relatively short period of time, its fossils would show up in limited layers.

29 Index fossils are fossils of organisms that lived for a relatively short, well defined geologic timespan. To be index fossils, these must be found throughout the world in rock layers. Think critically-- Evaluate why are the best index fossils widespread? Explain how scientist might be able to determine the relative age of a layer of sediment if they find a fossilized trilobite in the layer. List ways in which fossils can form. Trilobites

30 Using Fossils to Interpret the Past
Fossils can reveal changes in the environment. Scientists have found marine fossils on mountaintops (e.g. Yoho National Park) The presence of these fossils means that rocks were once below the surface of an ocean. Middle TN, specifically Murfreesboro, was once covered by a shallow sea. Marine fossils found in the limestone tell scientists that.

31 FINDASAURUS ACTIVITY Scenario: A paleontologist from Tennessee went on vacation to Montana where he discovered dinosaur bones in a particular layer of rock. He wondered if the same layer existed in Tennessee so he could find bones closer to home. If that particular rock appears on Earth’s surface, continuously, all the way from Montana to Tennessee he would be able to walk along the layer to follow it. That would be easy, but unfortunately, the easy way never seems to work. Erosion would make it impossible to follow the layer all the way from Montana to Tennessee. One of the most reliable ways to locate fossils is with other fossils. Index fossils can be used to track a layer from Montana to Tennessee, or from Montana to France. Relative dating places events in sequence within the rock layers while the process of determining if layers in different places are the same is called correlation.   1.There are two stacks of rock layers, one in Montana and one in France. Your job is to determine: Which layers in Montana correlate with layers in France by matching the letters. Which layer in France contains the same dinosaur fossil as layer “d” in Montana.   2.Draw the fossils in the layers shown on the chart. For example, index fossil #2 should be drawn only in layers c and i. Make your best effort at reproducing the drawing.   3.Using colored pencils connect the borders of the rock layers in Montana with those in France. 2-minute journal reflection using accountable talk ( I hypothesize that ...) on which layer is correct and what you learned today.


33 Exit Ticket

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