6 th Grade Science Formula C x 95

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6 th Grade Science

6 th Grade Science

 • Formula • °C x 9/5 + 32 = °F • (°F -

• Formula • °C x 9/5 + 32 = °F • (°F - 32) x 5/9 = °C • Examples • 1) Convert 37°C to Fahrenheit. • 37°C x 9/5 + 32 = 98. 6°F • OR • 37°C x 9 + 32 = 98. 6°F 5 • 2) Convert 98. 6°F to Celsius. • (98. 6°F - 32) x 5/9 = 37°C • OR • (98. 6°F - 32) x 5 = 37°C • 9 © Fall 2005, Pflugerville ISD, 8 th Grade

“The present is the key to the past. ” -James Hutton What Do You

“The present is the key to the past. ” -James Hutton What Do You Think? We study the past because if we don’t, we are doomed to repeat it. But how can studying the present help us understand earth’s history? What are some processes you can see today that also occurred millions of years ago? © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened • “The present is the key to the

Earth’s Story & Those Who Listened • “The present is the key to the past. ” James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD, 8 th Grade • Father of modern geology

Earth’s Story & Those Who Listened • Hutton knew that Hadrian’s wall was built

Earth’s Story & Those Who Listened • Hutton knew that Hadrian’s wall was built by the Romans in historical times Hadrian’s Wall, England © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened Hadrian’s Wall, England © Fall 2005, Pflugerville ISD,

Earth’s Story & Those Who Listened Hadrian’s Wall, England © Fall 2005, Pflugerville ISD, 8 th Grade • Only 1600 years old, the wall was already starting to weather and erode

Earth’s Story & Those Who Listened Arthur’s Seat Volcano, Edinburgh, Scotland © Fall 2005,

Earth’s Story & Those Who Listened Arthur’s Seat Volcano, Edinburgh, Scotland © Fall 2005, Pflugerville ISD, 8 th Grade • Hutton wondered how long it would take to erode a mountain

Earth’s Story & Those Who Listened Arthur’s Seat Volcano, Edinburgh, Scotland © Fall 2005,

Earth’s Story & Those Who Listened Arthur’s Seat Volcano, Edinburgh, Scotland © Fall 2005, Pflugerville ISD, 8 th Grade • Hutton decided that it would take millions of years, making the earth very ancient

Earth’s Story & Those Who Listened Arthur’s Seat Volcano, Edinburgh, Scotland © Fall 2005,

Earth’s Story & Those Who Listened Arthur’s Seat Volcano, Edinburgh, Scotland © Fall 2005, Pflugerville ISD, 8 th Grade • Hutton realized that erosion and deposition have been going on for a long time

Earth’s Story & Those Who Listened • In 1788, James Hutton • wrote: •

Earth’s Story & Those Who Listened • In 1788, James Hutton • wrote: • Theory of the Earth • (a collection of his notes) © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened In his book he described: • Uniformitarianism James

Earth’s Story & Those Who Listened In his book he described: • Uniformitarianism James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD, 8 th Grade • It is the idea that the same geologic processe shaping the Earth today have been at work throughout Earth’s history.

Earth’s Story & Those Who Listened James Hutton 1726 -1797 © Fall 2005, Pflugerville

Earth’s Story & Those Who Listened James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD, 8 th Grade • Hutton’s views of a billion-year-old earth clashed with most scientists’ belief in catastrophism

Earth’s Story & Those Who Listened • Most scientists supported catastrophism. I is the

Earth’s Story & Those Who Listened • Most scientists supported catastrophism. I is the idea that al geologic change happens quickly © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened • These scientists used huge floods, eruptions, and

Earth’s Story & Those Who Listened • These scientists used huge floods, eruptions, and other catastrophes to explain rapid geologic change © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened • Catastrophism was a guiding principle for decades.

Earth’s Story & Those Who Listened • Catastrophism was a guiding principle for decades. • Only after the work of Charles Lyell did people consider uniformitarism. • 1830 -1833 Lyell published 3 volumes in: – Principles of Geology – In it, he stated that change happened gradually. © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened • Today, scientists think that sudden events are

Earth’s Story & Those Who Listened • Today, scientists think that sudden events are the cause of some changes in earth’s past © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story & Those Who Listened • But they agree that the earth is

Earth’s Story & Those Who Listened • But they agree that the earth is old, and that most change is gradual © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story and Those Who First Listened Today’s Scientists realize that neither of these

Earth’s Story and Those Who First Listened Today’s Scientists realize that neither of these principles: uniformitarianism nor catastrophism account for all geologic changes. Most change is gradual, but catastrophes have occurred throughout Earth’s history. © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story and Those Who First Listened paleontology-science involved with the study of past

Earth’s Story and Those Who First Listened paleontology-science involved with the study of past life paleontologist-a scientist who studies past life What data do they study? Fossils © Fall 2005, Pflugerville ISD, 8 th Grade

Earth’s Story and Those Who First Listened fossils-the remains of organisms preserved by geologic

Earth’s Story and Those Who First Listened fossils-the remains of organisms preserved by geologic processes Invertebrate paleontologist-studies animals without backbones Vertebrate Paleontologist-studies animals with backbones © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? What Do You Think? Suppose your friend piles his

Relative Dating: Which came first? What Do You Think? Suppose your friend piles his stuff on his floor and never cleans his room. Under the top layer of clothes, you find a pizza box. Under this is a bunch of CDs then some homework and under this is a ham sandwich. Arrange these four layers from oldest to youngest… © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? relative dating-determining whether an object or event is older

Relative Dating: Which came first? relative dating-determining whether an object or event is older or younger than other objects or events © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • The Principle of Superposition states that younger rocks

Relative Dating: Which came first? • The Principle of Superposition states that younger rocks lie over older rocks Grand Canyon © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • The Principle of Superposition is used to find

Relative Dating: Which came first? • The Principle of Superposition is used to find the relative ages of rock layers Grand Canyon © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD,

Relative Dating: Which came first? James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD, 8 th Grade • Geologists can use rock layers from many locations to create a geologic column

Relative Dating: Which came first? • The geologic column is an ideal sequence of

Relative Dating: Which came first? • The geologic column is an ideal sequence of rock layers that contains all known rock formations and fossils on Earth © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • The dike is the youngest feature, because the

Relative Dating: Which came first? • The dike is the youngest feature, because the other layers were cut by it © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? Look at page 66 Figure 3 Terms: fault-a break

Relative Dating: Which came first? Look at page 66 Figure 3 Terms: fault-a break in the Earth’s crust along which blocks of the crust slide relative to on another intrusion-molten rock from the Earth’s interior that squeezes into existing rock and cools © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? folding-occurs when rock layers bend and buckle from Earth’s

Relative Dating: Which came first? folding-occurs when rock layers bend and buckle from Earth’s internal forces tilting-occurs when internal forces in the Earth slant rock layers These features are younger than the rock layers because the rock layers had to be present before the features could cut across them. © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • The Law of Cross-Cutting Relationships can tell geologists

Relative Dating: Which came first? • The Law of Cross-Cutting Relationships can tell geologists the relative age of a fault or intrusion © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • Use your knowledge to order the layers, faults

Relative Dating: Which came first? • Use your knowledge to order the layers, faults and intrusions in the next slide from oldest to youngest © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • If rock layers are not horizontal, something must

Relative Dating: Which came first? • If rock layers are not horizontal, something must have disturbed them after they formed. © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • An unconformity is a surface that represents a

Relative Dating: Which came first? • An unconformity is a surface that represents a missing part of Hutton’s Unconformity the geologic column © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? • Most unconformities form by erosion and nondeposition. ©

Relative Dating: Which came first? • Most unconformities form by erosion and nondeposition. © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? Types of unconformities: 1. disconformities-are found where part of

Relative Dating: Which came first? Types of unconformities: 1. disconformities-are found where part of a sequence of parallel rock is missing. This is the most common type. © Fall 2005, Pflugerville ISD, 8 th Grade

Formation of an Unconformity • Sediment is eroded from a hil and deposited in

Formation of an Unconformity • Sediment is eroded from a hil and deposited in a valley 30 -15 Million Years Ago © Fall 2005, Pflugerville ISD, 8 th Grade

Formation of an Unconformity • The area is uplifted and exposed to erosion, then

Formation of an Unconformity • The area is uplifted and exposed to erosion, then the land surface is eroded away 15 -5 Million Years Ago © Fall 2005, Pflugerville ISD, 8 th Grade

Formation of an Unconformity • Deposition resumes • Can you spot the unconformity? 5

Formation of an Unconformity • Deposition resumes • Can you spot the unconformity? 5 Million Years Ago. Present © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? 2. nonconformities-are found where horizontal sedimentary rock layers lie

Relative Dating: Which came first? 2. nonconformities-are found where horizontal sedimentary rock layers lie on top of an eroded surface of older intrusive igneous or metamorphic rock © Fall 2005, Pflugerville ISD, 8 th Grade

Relative Dating: Which came first? 3. angular unconformities-are found between horizontal layers of sedimentary

Relative Dating: Which came first? 3. angular unconformities-are found between horizontal layers of sedimentary rock and layers of rock that have been tilted or folded. © Fall 2005, Pflugerville ISD, 8 th Grade

Section 3: Absolute Dating • Absolute dating-the process of establishing the age of an

Section 3: Absolute Dating • Absolute dating-the process of establishing the age of an object by determining the number of years it has existed © Fall 2005, Pflugerville ISD, 8 th Grade

How is this done? • element-a substance that cannot be separated or broken down

How is this done? • element-a substance that cannot be separated or broken down into simpler substances by chemical means • atom-the smallest unit of an element that maintains the properties of that element • isotope-atoms of the same element that have the same number of protons but a different number of neutrons © Fall 2005, Pflugerville ISD, 8 th Grade

An atom is made of protons, neutrons, and electrons. © Fall 2005, Pflugerville ISD,

An atom is made of protons, neutrons, and electrons. © Fall 2005, Pflugerville ISD, 8 th Grade

Rules • In a stable atom, protons and electrons are equal. © Fall 2005,

Rules • In a stable atom, protons and electrons are equal. © Fall 2005, Pflugerville ISD, 8 th Grade

Radioactive-this is what scientists call unstable isotopes Radioactive decay-a process where radioactive isotopes tend

Radioactive-this is what scientists call unstable isotopes Radioactive decay-a process where radioactive isotopes tend to break down into stable isotopes of the same or other elements © Fall 2005, Pflugerville ISD, 8 th Grade

Radioactive Decay Daughter Isotope Parent Isotope Unstable Isotope 6 protons, 8 neutrons © Fall

Radioactive Decay Daughter Isotope Parent Isotope Unstable Isotope 6 protons, 8 neutrons © Fall 2005, Pflugerville ISD, 8 th Grade Radioactive Decay When some unstable isotopes decay a neutron is converted into a proton. An electron is released Stable Isotope 7 protons, 7 neutrons

What does this show you? • Scientists can use it to determine an object’s

What does this show you? • Scientists can use it to determine an object’s age (like rocks or fossils) © Fall 2005, Pflugerville ISD, 8 th Grade

How is this done? • parent isotope-the unstable radioactive isotope • daughter isotope-the stable

How is this done? • parent isotope-the unstable radioactive isotope • daughter isotope-the stable isotope that is produced by the radioactive decay of the parent isotope © Fall 2005, Pflugerville ISD, 8 th Grade

How do Scientists Date Rock? • They compare the amount of parent material with

How do Scientists Date Rock? • They compare the amount of parent material with the amount of daughter material. The more daughter material, the older the rock is. • The rate of decay is constant. © Fall 2005, Pflugerville ISD, 8 th Grade

 • If you know the rate of decay for a radioactive element in

• If you know the rate of decay for a radioactive element in a rock, you can figure out the absolute age of the rock. • Radiometric dating-determining the absolute age of a sample based on the ratio of parent to daughter material © Fall 2005, Pflugerville ISD, 8 th Grade

 • half life-it is the time that it takes one half of a

• half life-it is the time that it takes one half of a radioactive sample to decay • Activity on page 70 © Fall 2005, Pflugerville ISD, 8 th Grade

Types of Radiometric Dating 1. Potassium-Argon Method Potassium-40 (parent) decays to argon (daughter) Mainly

Types of Radiometric Dating 1. Potassium-Argon Method Potassium-40 (parent) decays to argon (daughter) Mainly used on rocks older than 100, 000 years. © Fall 2005, Pflugerville ISD, 8 th Grade

2. Uranium-Lead Method Uranium-238 (parent) is a radioactive material that decays to lead (daughter).

2. Uranium-Lead Method Uranium-238 (parent) is a radioactive material that decays to lead (daughter). The older the rock, the more lead there will be. This can be used for rocks more than 10 million years old. It is not accurate for younger rocks. © Fall 2005, Pflugerville ISD, 8 th Grade

3. Rubidium-Strontium Method Parent rubidium/Daughter Strontium Used to date rocks older than 10 million

3. Rubidium-Strontium Method Parent rubidium/Daughter Strontium Used to date rocks older than 10 million years. © Fall 2005, Pflugerville ISD, 8 th Grade

4. Carbon-14 Method Carbon is found in 3 forms: Carbon-12 & Carbon-13 (both stable)

4. Carbon-14 Method Carbon is found in 3 forms: Carbon-12 & Carbon-13 (both stable) and Carbon-14 (radioactive) All of these combine with oxygen to form carbon dioxide. This is taken in by plants. © Fall 2005, Pflugerville ISD, 8 th Grade

 • Once a plant dies, the amount of carbon 14 begins to decrease

• Once a plant dies, the amount of carbon 14 begins to decrease as the plant decays. The ratio of carbon-14 to carbon-12 decreases with time and can be used to determine dating for things that lived within the last 50, 000 years. © Fall 2005, Pflugerville ISD, 8 th Grade

Absolute Dating • When animals eat, they ingest radioactive Carbon-14 © Fall 2005, Pflugerville

Absolute Dating • When animals eat, they ingest radioactive Carbon-14 © Fall 2005, Pflugerville ISD, 8 th Grade

Absolute Dating © Fall 2005, Pflugerville ISD, 8 th Grade • Since C-14 has

Absolute Dating © Fall 2005, Pflugerville ISD, 8 th Grade • Since C-14 has a half-life of only 5730 years, other isotopes are used to date older rocks

Absolute Dating James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD, 8 th Grade

Absolute Dating James Hutton 1726 -1797 © Fall 2005, Pflugerville ISD, 8 th Grade • The oldest rocks on Earth have been dated to 4. 5 billion years, confirming Hutton’s beliefs

 • Interactive Time Scale • Start on Abraham Lincoln © Fall 2005, Pflugerville

• Interactive Time Scale • Start on Abraham Lincoln © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • A fossil is the remains or physical evidence of an

Looking at Fossils • A fossil is the remains or physical evidence of an organism preserved by geologic Saber-Tooth Cat processes Fossil © Fall 2005, Pflugerville ISD, 8 th Grade

What happens when something dies • It is either consumed by other organisms or

What happens when something dies • It is either consumed by other organisms or immediately begins decaying. • Being buried by sediment, slows down the decay. • Hard parts like bone and shells are more resistant to decaying, so more commonly preserved. © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • Fossilized tree sap is called amber Fossil Amber with Insect

Looking at Fossils • Fossilized tree sap is called amber Fossil Amber with Insect Inclusions © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • Animals caught in amber are perfectly preserved Fossil Amber with

Looking at Fossils • Animals caught in amber are perfectly preserved Fossil Amber with Insect Inclusions © Fall 2005, Pflugerville ISD, 8 th Grade

 • Petrifaction-a process in which minerals replace an organism’s tissues © Fall 2005,

• Petrifaction-a process in which minerals replace an organism’s tissues © Fall 2005, Pflugerville ISD, 8 th Grade

Types of Petrifaction • Permineralization-a process in which the pore space in an organism’s

Types of Petrifaction • Permineralization-a process in which the pore space in an organism’s hard tissue (like bone or wood) is filled up with minerals • Replacement-a process in which the organism’s tissues are completely replaced by minerals Ø An example, is petrified wood. © Fall 2005, Pflugerville ISD, 8 th Grade

Fossils in Asphalt © Fall 2005, Pflugerville ISD, 8 th Grade

Fossils in Asphalt © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • Fossils of mammoths, extinct for approximately 10, 000 years, have

Looking at Fossils • Fossils of mammoths, extinct for approximately 10, 000 years, have been found frozen in Arctic ice. Woolly Mammoth October 1999 Scientist removed a 20, 000 yr. old mammoth in Siberian tundra. © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • A trace fossil is naturally preserved evidence of animal activity.

Looking at Fossils • A trace fossil is naturally preserved evidence of animal activity. Theropod Track © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils Theropod Track © Fall 2005, Pflugerville ISD, 8 th Grade •

Looking at Fossils Theropod Track © Fall 2005, Pflugerville ISD, 8 th Grade • This dinosaur track is located in Glen Rose, Texas, in Dinosaur Valley State Park

Types of Trace Fossils • Burrows-shelters made by animals • Coprolite-preserved animal dung ©

Types of Trace Fossils • Burrows-shelters made by animals • Coprolite-preserved animal dung © Fall 2005, Pflugerville ISD, 8 th Grade

Things you can Learn from Fossils: • how big it was, • how fast

Things you can Learn from Fossils: • how big it was, • how fast it was moving, • and whether they move in herds or not. © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • A mold is a cavity in rock where a plant

Looking at Fossils • A mold is a cavity in rock where a plant or animal was buried. Ammonite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • A cast is an object made when sediment fills a

Looking at Fossils • A cast is an object made when sediment fills a mold and becomes rock. Ammonite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils • Which of these is the mold and which is the

Looking at Fossils • Which of these is the mold and which is the cast? Ammonite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils Whale Bones © Fall 2005, Pflugerville ISD, 8 th Grade •

Looking at Fossils Whale Bones © Fall 2005, Pflugerville ISD, 8 th Grade • Most animals are not buried fast enough to form fossils

Looking at Fossils Whale Bones © Fall 2005, Pflugerville ISD, 8 th Grade •

Looking at Fossils Whale Bones © Fall 2005, Pflugerville ISD, 8 th Grade • These whale bones will be broken down before they can form fossils

Why is the fossil record incomplete? • Because most organisms never became fossils. •

Why is the fossil record incomplete? • Because most organisms never became fossils. • Also, many fossils have yet to be discovered. © Fall 2005, Pflugerville ISD, 8 th Grade

What does the fossil record reveal? • A history of environmental change For example:

What does the fossil record reveal? • A history of environmental change For example: – A marine fossil helps scientists reconstruct ancient coastlines and the depth of ancient seas. – It allows scientists to reconstruct past climates – They can determine how life has changed overtime. © Fall 2005, Pflugerville ISD, 8 th Grade

Fossils • Certain types of fossils only appear in certain layers of rock, so

Fossils • Certain types of fossils only appear in certain layers of rock, so by dating the rock layers above and below these fossils, scientists can determine the time span that the fossil formed. © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils Trilobite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade •

Looking at Fossils Trilobite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade • An index fossil is one found for a short time in rock layers around the world

Examples of an Index Fossil 1. Genus of Ammonites called Tropites • These were

Examples of an Index Fossil 1. Genus of Ammonites called Tropites • These were marine mollusk similar to a modern squid. It lived in a coiled shell. • They are believed to have lived 230 and 208 million years ago. © Fall 2005, Pflugerville ISD, 8 th Grade

2. Genus of Trilobites called Phacops • Their closest relative is the horseshoe crab

2. Genus of Trilobites called Phacops • Their closest relative is the horseshoe crab • They are believed to have lived 400 million years ago. © Fall 2005, Pflugerville ISD, 8 th Grade

Looking at Fossils Trilobite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade •

Looking at Fossils Trilobite Fossil © Fall 2005, Pflugerville ISD, 8 th Grade • The trilobite (Phacops) lived for a short time 400 million years ago.

Time Marches On Dinosaur Quarry Visitor Center Dinosaur National Monument , Utah • 1,

Time Marches On Dinosaur Quarry Visitor Center Dinosaur National Monument , Utah • 1, 500 bones excavated • Approximately 150 million yrs. old • This is 3%of the time Earth has existed.

 One of the best places to see the Earth’s history recorded in rock

One of the best places to see the Earth’s history recorded in rock layers is the: Grand Canyon

Colorado River The river has eroded countless layers of rock.

Colorado River The river has eroded countless layers of rock.

Time Marches On Humans First Arrived

Time Marches On Humans First Arrived

 • Green River Formation • These rocks are found in parts of Wyoming,

• Green River Formation • These rocks are found in parts of Wyoming, Utah, and Colorado. They are thousands of meters thick. • They were once a part of a system of ancient lakes. • Fossils of plants and animals are common and well preserved. © Fall 2005, Pflugerville ISD, 8 th Grade

Time Marches On • The Geologic Time Scale divides Earth’s history into intervals of

Time Marches On • The Geologic Time Scale divides Earth’s history into intervals of time. © Fall 2005, Pflugerville ISD, 8 th Grade

Divisions of Time • eon-largest divisions of geologic time There are 4 eons: 1.

Divisions of Time • eon-largest divisions of geologic time There are 4 eons: 1. 2. 3. 4. Hadean eon Archean eon Proterozoic eon Phanerozoic eon-it is divided into 3 eras © Fall 2005, Pflugerville ISD, 8 th Grade

Divisions of Time • era-the second largest division of geologic time that includes two

Divisions of Time • era-the second largest division of geologic time that includes two or more periods -3 eras are divided in to periods • periods-the third largest division of geologic time into which eras are divided -periods are divided into epochs • epochs-the fourth largest division of geologic time that is a subdivision of a period © Fall 2005, Pflugerville ISD, 8 th Grade

Time Marches On • Since most fossils are from the Phanerozoic Eon, this is

Time Marches On • Since most fossils are from the Phanerozoic Eon, this is the eon that is given the most attention. © Fall 2005, Pflugerville ISD, 8 th Grade

Time Marches On • The Phanerozoic is actually the shortest of the four eons.

Time Marches On • The Phanerozoic is actually the shortest of the four eons. © Fall 2005, Pflugerville ISD, 8 th Grade

Time Marches On Paleozoic Era 543 -248 mya © Fall 2005, Pflugerville ISD, 8

Time Marches On Paleozoic Era 543 -248 mya © Fall 2005, Pflugerville ISD, 8 th Grade • In the Paleozoic Era, life in the oceans, as well as all major plant groups and insects, flourished.

 • The Paleozoic era came to an end with the largest mass extinction

• The Paleozoic era came to an end with the largest mass extinction in Earth’s history. • Some scientists believe that the oceans were the cause of extinction. • It killed nearly 90% of all species. © Fall 2005, Pflugerville ISD, 8 th Grade

 • extinction-the death of every member of a species © Fall 2005, Pflugerville

• extinction-the death of every member of a species © Fall 2005, Pflugerville ISD, 8 th Grade

Time Marches On Mesozoic Era 248 -65 mya © Fall 2005, Pflugerville ISD, 8

Time Marches On Mesozoic Era 248 -65 mya © Fall 2005, Pflugerville ISD, 8 th Grade • With a mass extinction at the end of the Paleozoic, the remaining reptiles thrived

Time Marches On Mesozoic Era 248 -65 mya © Fall 2005, Pflugerville ISD, 8

Time Marches On Mesozoic Era 248 -65 mya © Fall 2005, Pflugerville ISD, 8 th Grade • Known as the Age of Reptiles, birds and small mammals appeared late in the Mesozoic

Time Marches On Cenozoic Era 65 mya- Present © Fall 2005, Pflugerville ISD, 8

Time Marches On Cenozoic Era 65 mya- Present © Fall 2005, Pflugerville ISD, 8 th Grade • Mammals flourished after a mass extinction killed the dinosaurs

Mesozoic Era • 15 -20% of all species became extinct. • Why? Global climate

Mesozoic Era • 15 -20% of all species became extinct. • Why? Global climate change is possible. © Fall 2005, Pflugerville ISD, 8 th Grade

Time Marches On • The Cenozoic is known as the Age of Mammals Cenozoic

Time Marches On • The Cenozoic is known as the Age of Mammals Cenozoic Era 65 mya- Present © Fall 2005, Pflugerville ISD, 8 th Grade

Let’s Review! - 1 - What did James Hutton mean by the comment, “The

Let’s Review! - 1 - What did James Hutton mean by the comment, “The present is the key to the past”? © Fall 2005, Pflugerville ISD, 8 th Grade

Let’s Review! - 2 - How can you tell the age of rocks and

Let’s Review! - 2 - How can you tell the age of rocks and fossils? © Fall 2005, Pflugerville ISD, 8 th Grade

Let’s Review! - 3 - How is a fossil created? Describe how a geologist

Let’s Review! - 3 - How is a fossil created? Describe how a geologist would use an index fossil… © Fall 2005, Pflugerville ISD, 8 th Grade

Let’s Review! - 4 - What type of event ended both the Paleozoic and

Let’s Review! - 4 - What type of event ended both the Paleozoic and Mesozoic Eras? What geologic time period was occurring 200 million years ago? © Fall 2005, Pflugerville ISD, 8 th Grade

Pre-AP Extensions © Fall 2005, Pflugerville ISD, 8 th Grade

Pre-AP Extensions © Fall 2005, Pflugerville ISD, 8 th Grade