Answers will vary. Sample answer: Before the formation of a mold and cast occurs, an organism dies and its hard body parts make an impression in soft sediment. Comparative anatomy.
The mix gets hot as it sets—do not touch it until it has hardened. Remove the shell fossil from the sand, and brush it off. Observe the structure of the fossil, and record your observations. Data and Observations Think About This 1. What effect did the shell have on the sand? Shaded letters will not be used. Crack the code by using the clues for hints.
Key concept builder lesson 3 absolute age dating you read the clues and fill in the blanks, complete the chart with the number that corresponds to each letter you have used. The Fossil Record 1. All the fossils ever discovered on Earth make up the.
Fossils help scientists figure out what species that no longer looked like when the organisms were alive. Fossil Formation 1. Most fossils are formed of the parts of an organism. Sometimes when the remains of an organism get buried in mud, wet sand, or other sediments under a body ofthe molecules that formed the remains get replaced by in the water. This type of fossil formation is called. Most mineralized fossils are formed of shell orbut wood can also become a mineralized fossil.
Sometimes organisms or parts of organisms make a n in sand or mud. The kind of fossil that forms as an impression in rock is called a n. If the impression gets filled with sediments that harden to rock, a n is the result.
Molds and casts show only features of organisms.
Unit 2 Lesson 3 Absolute Dating
The preserved evidence of the activity of an organism, such as its tracks, is called a n 6. In rare cases, the original preserved, such as fossil. Scientists cannot date most usually find the age of the 10 directly. Instead they around the fossils. In dating, scientists determine the relative order in which rock layers were deposited.
In a n rock formation, the older layers of rock are below the younger layers of rock. Relative-age dating has helped scientists figure out the order that have appeared on Earth. Absolute-age dating is more than relative-age dating and involves isotopes that decay to become stable isotopes over time. The time units. Neither eons nor eras are in length.
When scientists began developing the geologic time scale in the s, they did not have dating methods, so they marked time boundaries with.
Extinctions 1. When the last individual organism of a species dies, a n has occurred. A n extinction occurs when many species die off within a few million years haiti websites less.
The fossil record shows evidence of mass extinctions during the Phanerozoic eon. Extinctions can occur if the changes quickly; for example, as a result of a metorite impact. Extinctions can also occur if the environment changes ; for example, as a result of the formation of mountain ranges.
The fossil record contains clear evidence of the extinction of species over time as well as evidence of the appearance of many new The Environment and Change Over Time. Over long time periods free dating social network Earth, certain individuals within populations of organisms were able to survive better than others. Choose a species from the Species 3. Use information from the I.
Card to show what you think would be the progression of key concept builder lesson 3 absolute age dating in the species in frames 2—5. On chart paper, draw six squares in a row and number them 1—6, respectively.
Use colored pencils and markers to make a comic strip showing the ancestral and present-day forms of your species in frames 1 and 6.
Lesson 1 | Fossil Evidence of Evolution
In speech bubbles, explain how each change helped the species to survive. Analyze and Conclude 1. Infer why a scientist would identify a fossil from the species in the first frame of your cartoon as the ancestral form of the present-day species. Key Concept How would the fossils of the species at each stage provide evidence of biological change over time? Archean 2. Cenozoic 3. Hadean 4. Mesozoic 5.
Paleozoic 6. Phanerozoic 7. Precambrian 8. Use complete sentences. Unit 2 Lesson 3 Absolute Dating How can the absolute age of rock be determined? Radioactive isotopes, also called radioisotopes, are isotopes that are unstable and break down into other, stable isotopes by a process called radioactive decay.
As they break down, they release excess energy by emitting radiation in the form of alpha, beta and gamma rays. The radioactive isotope is called the parent key concept builder lesson 3 absolute age dating, and the stable isotope formed by its breakdown is called the daughter isotope. Half-life is the time needed for half of a sample of a radioactive element to undergo radioactive decay and form daughter isotopes.Absolute-Age Dating
Scientists study the amounts of parent and daughter isotopes to date samples. Finding the absolute age of a sample by determining the relative percentages of a radioactive parent isotope and a stable daughter isotope is called radiometric dating. Unit 2 Lesson 3 Absolute Dating What is the best rock for radiometric dating?
Igneous rocks are the best types of rock samples to use for radiometric dating. When igneous rocks form, minerals in them often contain only a parent isotope and none of the daughter isotope.
This makes the isotope percentages easier to interpret and helps dating to be more accurate. Scientists use many different isotopes for radiometric dating. The type of isotope used depends on the type of material being dated. The half-life of the isotope used is also very important.
Unit 2 Lesson 3 Absolute Dating What are some radiometric dating methods? Radiocarbon dating is a method used for dating wood, bones, shells, and other organic remains. All living things have a constant ratio of radioactive carbon to carbon Once a plant or an animal dies, no more carbon is taken in.
The ratio between the isotopes changes because carbon undergoes radioactive decay. The half-life of carbon is 5, years. The number of half-lives of carbon that have passed gives the absolute age.
Sample answer: First, carbonization may occur when a dead organism is compressed over time. Next, the pressure drives off the organisms liquids and gases. As a result, all that remains is the carbon outline of the organism.
Sample answer: Before the formation of a mold key concept builder lesson 3 absolute age dating cast occurs, an organism dies and its hard body parts make an impression in soft sediment. As the sediment hardens, so does the impression, forming a mold. Then, sediments can later fill in the mold. Over time, these sediments might harden into a cast. Language Arts Support page 16 Sample answer: When an environmental change occurs, extinctions can take place.
After changes, such as volcanic eruptions, individuals of a species might not be able to obtain the resources they need to. Answers continued survive. Then, if all organisms of a species die, the species becomes extinct.
Some environmental changes, such as meteorite impacts, occur rapidly. Other environmental changes, such as the movement of tectonic plates or changes in sea level, find friends gradually.
As a result, rapid and gradual changes in the environment can lead to extinction. School to Home page 18 1. Students drawings should show a fossil in each of the following rock layers: B, C, E, and G. The term younger should be written at the top of the arrow. The term older should be written at the bottom of the arrow. The fossil in rock layer B is older; b. The fossils in rock layers E and G are younger. The youngest fossil is the one in rock layer G. This activity represents relative-age dating.
Rock layers B, C, E, and G are most likely sedimentary rock because most fossils are found in sedimentary rock. If rock layers Key concept builder lesson 3 absolute age dating, D, and F are igneous rock, absolute-age dating could be carried out.
Absolute-age dating, which can determine a more precise age for fossils, is best performed using igneous rocks. Key Concept Builder page 19 Accept information that appears in rows 15 presented in any order. For completed table, see page T Key Concept Builder page 20 1. Best app in india Concept Builder page 22 1.
The absence of fossils suggests some type of event that caused a mass extinction of organisms. A mass extinction can occur within a few million years or less. Extinctions take place when environments change quickly; gradual changes take place when environments slowly change. There have been five major extinction events in Earths history. Enrichment page 23 1. Possible answer: The Principle of Original Horizontality applies. When the strata were formed, they were horizontal.
An upheaval caused by volcanic, earthquake, or tectonic activity caused the horizontal layers to tip up on the left side and down on the right sloping down from left to right. One particular layer remains visible as a relatively unbroken stratum, but it is horizontally deformed. Look for scenarios that include deformations of Earths crust by volcanic, earthquake, or tectonic forces causing strata to tip or fold.
Students should indicate that if the samples are taken from the same depths, it does not mean that the fossils came from the same layer of sediment. Students should have a copy of the geologic time scale for reference that provides information on the appearance of life-forms in the fossil record.
Below is the list of key concept builder lesson 3 absolute age dating from the oldest at the bottom to the youngest at the top.Radiometric or Absolute Rock Dating
All fossils are found within the five periods listed, though those within each layer are assumed to be of the same relative age. All names of organisms are fictional. Look for drawings small holidays for singles have the information in the correct order and that are associated with the correct period of geologic time.
Students may be creative in the drawing of the rock strata, but they should not be assessed on creativity. The order can be quickly determined for most of the fossils by analyzing their names.
For example, hint key concept builder lesson 3 absolute age dating should indicate to students that Crawlitus fishensis might be an early fish and, therefore, could not be in the fossil record before the Ordovician Period.
Students may take a hint for drawing the fossils from their names. Lesson Quiz B page 28 Matching 1. D Short Answer 8.
Relative age dating is less precise than absolute-age dating. Relative-age find friends from all around the world uses the relative order in which rock layers were deposited to determine the relative order in which fossils, and the organisms they represent, appeared on Earth over time. Absolute-age dating uses radioactive decay to find the age of igneous rock layers, and then estimates the age of fossils embedded in sedimentary layers between them.
Answers will vary but should contain the idea that environmental change, whether it occurs suddenly or gradually, can have the effect of causing the extinction of species. Skill Practice pages 5. Answers will vary depending on the presentation form chosen. Encourage groups to use their own ideas, if feasible. Have student groups present their products to the class for discussion. Class members can offer constructive criticism, vote, or otherwise judge whether evidence exists that changes in common items over time have had an affect on their safety and efficiency.
Lesson Quiz A page 27 Multiple Choice 1. B Matching Set 1 3. The graph of measurements provides evidence that the length from the elbow to the tip of the middle finger varies within the class.
Content Vocabulary page 31 1. Camouflage is an adaptation that enables individuals of a species to blend in with their environments. Mimicry is another adaptation, whereby one species resembles another. Both adaptations help species avoid being eaten. The term scientist is a general term.
Scientists study and work with many different aspects of science. The term naturalist identifies a specific type of scientist. Naturalists study plants and animals through observation. A variation is a slight difference in the appearance of individual members of a species.
A particular variation might become. Answers continued more common through natural selection and lead to an adaptation, or a characteristic, of a species that enables the species to survive in its environment. Natural selection explains how populations change as their environments change. The process of selective breeding is similar to natural selection, but with important differences. Changes caused by selective breeding are due to human choice, while changes caused by natural selection are due to environmental changes.
If a person suspects something, the person thinks something is possible. If a person is convinced of something, the person has become certain of it as a result of argument or other support. MiniLab page 34 1. Answers will vary but should include descriptions of how the moths that were discovered did not blend into their background environment as well as the moths that were better camouflaged. Camouflage enables an organism to blend in with its environment.
This can help it avoid predators or surprise prey. Content Practice B page 36 1. School to Home page 37 a. Reproduction is the process of producing offspring.
Reproduction enables organisms to pass their characteristics on to offspring; b. A variation is a slight difference in the appearance of a member of a species. Beneficial variations make it easier for individuals to compete in an environment; c. Competition occurs when individuals in a population must share the same limited resources. Through competition, individuals with beneficial variations get more food and other resources than individuals without them; d.
Selection occurs. Natural selection results in helpful variations becoming more common within a population, eventually becoming adaptations. Key Concept Builder page 38 1. HMS Beagle 4. Galpagos Islands 5. South America 6. Key Concept Builder page 39 1. The characteristics are inherited by the offspring. They occur naturally in populations as a result of random mutations, or changes in genes.
Helpful variations that help organisms survive are key concept builder lesson 3 absolute age dating throughout the population as the organisms reproduce. Through natural selection, tortoises, finches, and other diverse species became matched to their food sources.
Answers continued 6. Key Concept Builder page 41 1. Camouflage is an adaptation that enables species to blend in with their environments. Students drawings will vary and might include an insect or bird blending into its environment.
Mimicry is the resemblance of one species to another species. Students drawings will vary and might include two similar types of butterflies or a caterpillar that looks like a snake.
Sample answer: This change is not caused by natural selection because each animal cannot naturally adapt to its environment for survival. However, characteristics are being selected for appearance or other reasons. A species that is unable to adapt to environmental changes will become extinct. Students answers might include a volcano or flood as an example of a quick environmental change.
Artificial selection is changes in a species that are the result of selective breeding. Sample answer: Artificial selection supports Darwins theory because it shows that those with certain characteristics reproduce and survive. Enrichment page 42 1. The goats that were raised to sell to the sailors and the rats from the ships are invasive and exotic species.
Others key concept builder lesson 3 absolute age dating the vermin from ships, such as insects, and some students might key concept builder lesson 3 absolute age dating humans as invasive. These are reasonable answers. Goats are grazers, much like the giant tortoises, but they are agile and able to reach food above and below the tortoises range. Goats outcompete tortoises and other slow grazers. Rats forage seeds and reproduce. Look for answers that show some insight into how Darwin thought about this very new theory and how it had to have time to grow and develop.
He may have used most of that time working out the kinks. He also did not want to encounter the criticism of the clergy and, therefore, he postponed the publication of this work for years.
Although it is true that Darwin spent years trekking around South America and that he made some profound observations while he was there, the five weeks in the Galpagos revealed to him some of the most unusual examples of animal species he had ever seen. This visit is what caused Darwin to examine the reasons that some species could be so similar and yet so different.
These questions helped him develop the foundation dating advice for men blog of biology, which is the theory of evolution by means of natural selection. Challenge page 43 1. One likely reason is that the background color changed from grassland color to the deeper green of food crops.
This gave the darker gray-colored variation a survival advantage. They were most likely better camouflaged from predators than the straw-colored variant in a field of green. Possible Answer: The dominant color variation in the lizard population was not changed deliberately by humans to promote the gray color.
Selective breeding is a technique that is used to emphasize and propagate specific traits or characteristics. In the case of the lizards, the color change was defensive and not purposeful. Lesson Quiz A page 44 True or False 1. F; selective breeding or artificial selection 3. F; Mimicry Multiple Choice 4.
Lesson Quiz B page 45 Short Answer 1. A naturalist studies plants and animals by observing them in their natural habitat. A mouth-shaped adaptation is the special mouth shape that a species has developed to obtain food and to survive. Students drawings might include the mouth shape of a pelican. Neither animal has a natural predator on the Galpagos Islands.
They outcompete the local animals for food and space. Answers continued 2. Answers will vary but should contain key concept builder lesson 3 absolute age dating idea that artificial selection demonstrates that the breeding of individuals with certain characteristics can cause a species to change over time. Camouflage and mimicry are similar because both are a type of structural adaptation that helps organisms avoid being eaten by predators. However, camouflage is an adaptation that enables a species to blend in with its environment, are drake and rihanna dating 2019 mimicry is an adaptation that causes one fairly harmless species to resemble another that predators avoid.
Answers will vary but should contain the idea that mutations are the cause of variation in populations. Natural selection is the process that causes species to change when their environments change. Completion 6. The spoons are similar in that each has a handle. Key concept builder lesson 3 absolute age dating are different at the part of the spoon that picks up food. It might be a plain stick, a long wooden slat hollowed out on one end, or a seashell attached to a stick.
Sample answer: A ladle is structured with a long handle and deep bowl for dipping out of a large container. A spoon with slots allows liquid to drain from food being key concept builder lesson 3 absolute age dating from a pot. A serving spoon is large enough to move serving-size amounts of food from a large serving dish to an individual plate.
These spoons are related because they have handles connected to the functional part. Content Vocabulary page 48 1. Comparative anatomy. MiniLab page 51 1. A dog and a turtle are more closely related than a dog and a silkworm. The dog and the turtle have more amino acids in common. The fewer the number of differences there are, the more closely related an organism is to a human. Content Practice A page 52 1. Content Practice B page 53 1. School to Home page 54 1. Although the structures are often used differently, their placement and structure point to a common ancestor.
For example, humans, cats, and birds have forelimbs with a similar structure, indicating that at some point they had the same ancestor with forelimbs. In an ancestral species, the structure was used for a specific purpose.
However, that purpose no longer exists. For example, a whale ancestor had pelvic bones that supported primitive rear legs. Because the animal spent most of its life in the water, whales evolved in a way that gradually eliminated the rear legs and the whale ancestors ability to walk on land. However, a primitive set of pelvic bones still exists in the whales skeleton, although they no longer have a function.
It indicates that there is a close evolutionary relationship between fish and other vertebrates. Genes of two living species can be compared. The more similar they are, the more closely the two species are related. Answers continued 5. The regular, predictable rate at which some stretches of DNA mutate can be used to measure the degree to which two species are related and how recently in the past the two species shared a common ancestor. Key Concept Builder page 55 1. Sample answer: information about homologous structures and analogous structures 6.
Sample answer: information on pharyngeal pouches 8. Sample answer: an understanding that gene mutations result in variations. Key Concept Builder page 56 Sample answers: 1. Examples include forelimbs of humans, cats, and birds. The similarity of the structures indicates a common ancestor. Pharyngeal pouches are a type of pouch shared by all vertebrate embryos.
The similarity in structure suggests an evolutionary relationship. Vestigial structures have lost their original function but indicate a common ancestor with other animals. The similarity in gene codes and proteins suggests a strong evolutionary relationship among all organisms. Stretches of DNA mutate at predictable rates, indicating when past species diverged from common ancestors. Key Concept Builder page 57 1. Key Concept Builder page 58 Sample answers: 1.
Some scientists think new species evolve slowly as small variations are gradually selected. Other scientists think change occurs rapidly with long periods of time between variations. Scientists think that DNA mutates, resulting in new species rising from a common ancestor. Diversity results when genes reorganize in simple ways and give rise key concept builder lesson 3 absolute age dating social anxiety dating website changes in organisms.
The theory of evolution by natural selection says that new species evolved from changes that occurred gradually as variations increased an organisms chances of survival. Enrichment page 59 1. Students answers will vary but should show logical reasoning and be supported by facts.
Students might choose some of the following criteria as a basis for classifying an animal as a free indian gay chat room having wings, having a bone structure suitable for flight, being warm-blooded, or other traits common to birds.
Students answers will vary but should show logical reasoning. Possible answer: The fact that Microraptor was about the size of a crow, had bones similar in structure to bird bones, and had feathers and toes like birds means that it probably was an ancestor to modern birds.
In addition, the fact that it had many dinosaurlike traits, key concept builder lesson 3 absolute age dating, such as the tail and teeth, means that it probably was a dinosaur. Therefore, birds and dinosaurs are closely related. The fact that the Microraptor had feathers even though it could not fly indicates that the feathers served another purpose than flight.
If the feathers were for insulation, then Microraptor, and at least some dinosaurs, were warm-blooded. Finally, the fact that Microraptor had toes that could have grasped tree branches means that birds probably learned to fly from trees down. Challenge page 60 Brochures should include information about why the structures are classified as homologous, analogous, or vestigial. Homologous: your nose, a pigs snout, and an elephants trunk These structures have a different appearance.
All are used for breathing, but each has other functions as well. For example, key concept builder lesson 3 absolute age dating, the elephants trunk can be used to grasp and manipulate objects. They are homologous because they arise from the same structure in a common ancestor. Examples include bird wings and fly wings. The difference in structure of these body parts indicates the organisms are not closely related. Answers continued Analogous: butterfly wing, airplane wing, bat wing All three structures have the same functionflight.
But each one arises separately from different origins, and one of them isnt a living organism. Nevertheless, they are analogous. Vestigial: cormorant wing, human tailbone, whale pelvic bone These structures are vestigial because they no longer have any function in the modern animal. Each of the structures can be traced to the form of an ancestor, however. For example, the pelvic bones in a whale indicate that the whale was once a fourlegged land dweller.
Lesson Quiz A page 61 Matching Set 1 1. B Matching Set 2 4. D Multiple Choice 7. Completion 1. Comparative anatomy 3. Embryology Short Answer 7. Answers will vary but should include the fact that some scientists think change in species occurs at a slow, steady rate, but other scientists think change occurs in rapid bursts.
Answers will vary but should contain the ideas that species formation is difficult to study because the fossil record is incomplete and that species formation does not occur in time intervals that humans can easily observe. Labs A and B pages 63, 66 9. Descriptions may include different types of variations, such as spiky skin or foot modification for faster running.
Extension Answers will vary. The events were presented in a different order, so the organisms might look completely different.PROBLEMS WITH FIND MY FRIENDS APP
The procedure given below is just one possibility of many. If you have student perform the labs they design, make sure proper safety precautions are included before allowing them to proceed. Sample procedure: Ask a Question How have different people contributed to our live links dating services of evolution today?
Form a Hypothesis Student hypotheses will vary, but the following is an example: If the ideas came key concept builder lesson 3 absolute age dating different thinkers over a period of time, then the ideas built on one another to form and support a well-founded theory because more evidence supported past ideas. Test Your Hypothesis Testing procedures will vary, but the following is an example: Have students research the contributions of the individuals listed, noting important dates and their ideas on an index card.
Have students arrange the index cards into a time line of the history of evolutionary thought. On the back of each card, have students write a statement inferring how that individuals contribution relates to the ideas in the Inquiry Lab Model Adaptations in an Organism. Have students share their inferences as a class. Analyze and Conclude Students should present an analysis of their data and some conclusion.
Chapter Key Concepts Builder page 70 Students should present visually appealing and informative reports. Connections should be made between trilobites and other arthropods.
Students should share that trilobites were marine arthropods that flourished in shallow salt water, but became extinct about mya when almost all marine animals became extinct. Students should report on environmental changes that may have resulted in the mass extinction of marine life some mya.
Chapter Test A page 72 Interpreting a Diagram 9. Chapter Test A page 73 Short Answer Fossils can be dated by relative-age dating. Scientists can find the relative order in which species appeared on Earth by determining the order of the rock layers in which they are embedded.
Absolute-age dating uses radioactive decay to determine the age of layers of igneous rock above and below the fossils, allowing scientists to estimate the age of the fossils embedded in sedimentary layers in between.
During radioactive decay, A. An absolute age of a mammoth bone could be determined using A. Radiometric methods provide accurate ages for A. Radiometric dating methods indicate that Earth is about A. Not all terms are used. Describe three objects that could be dated using the radioactive isotope carbon Explain how radiometric dating can be flirt 4 free online to date some rocks and not others.
Remember that geologists can correlate rock layers in different ways. In this lab, use index fossils to correlate and find the ages of the layers, key concept builder lesson 3 absolute age dating. Carefully examine the three rock columns on this page. Each rock layer can be labeled with a letter and a number.
For example, the second layer down in column A is layer A Look at the fossil key on the next page. It shows the time range during which each organism or group of organisms lived on Earth. Use the key to correlate the layers using only the fossils—not the types of rock. You might want to correlate by drawing lines to connect the layers. Analyze and Conclude 3. Differentiate Which fossils in the key seem to be index fossils?
Explain your choices. Match Correlate layer A-2 to one layer in each of the other two columns. Approximately how old are these layers? How do you know? Infer What is the age of layer B-4? Hint: It lies between two index fossils. Infer How old is the fault in column C?
Compare and Contrast How is correlating rocks using fossils different from correlating rocks using types of rock? The Big Idea How can fossils be used to figure out the relative ages of rocks? Communicate Your Results Choose a partner. One of you is a reporter and one is a geologist. Conduct an interview about what kinds of fossils are best used to date rocks. Recall that geologists can correlate rock layers in different ways. In this lab, use index fossils to correlate and date the layers.
Each rock layer can be identified with a letter and a number. Correlate the layers using only the fossils—not the types of rock. Before you begin, look at the fossil key on the next page. It shows the time intervals during which each organism or group of organisms lived on Earth. Refer to the key as you correlate. Lab Tips You might want to copy the rock layers in your Science Journal and correlate them by drawing lines connecting the layers.
Differentiate Which fossils in the key appear to be index fossils? Explain your choices 4. Infer What is the approximate age of layer B-4? Compare and Contrast How does correlating rocks using fossils differ from correlating rocks using types of rock?
The Big Idea How can fossils be flirt smileys whatsapp to determine the relative ages of rocks?
Extension Choose one of the three rock formations you correlated. Based on your results, provide a range of dates for each of the layers within it. You have learned that rock types and index fossils are important tools for scientists to use when they need to determine the relative ages of rock layers.
In this lab, you will determine a way to identify ten events that have been important in your life. Then you will correlate your events with those of a partner.
Use your understanding of the key concept builder lesson 3 absolute age dating of relative age and the Principle of Superposition to form a hypothesis of how you will correlate your events with those of your partner. How are these procedures similar to the tasks of a geologist?
Please note that you must complete Lab B before beginning Lab C. Have your teacher approve your design and safety procedures before beginning your experiment. Here is what you need to do to complete this activity: As a group, list the important concepts from this chapter. Which item is NOT a fossil? Which object would most likely become a fossil? Which meet guys in london is a trace fossil?
What is a relative age? What is a half-life? Which object could be accurately dated using carbon? Earth itself B. Each term is used only once 8.
Interpret Which one is older—rock A or rock B? Identify Rock A is an igneous rock. The thin, black bed above it is coal, a sedimentary rock.
What type of unconformity exists at point D? Sequence Feature G is a fault. Did the fault occur before or after rock layer F was deposited? Compare Which one is older—rock C or rock B? Contrast fossil molds and fossil casts.
List three characteristics of index fossils. Concept Application Directions: Answer the question or respond to each statement on the lines provided. Describe how the fossils formed. Also explain how this part of Earth has changed over time.CHOOSING A GOOD USERNAME FOR DATING
Infer three things that can be learned about ancient organisms by studying similarlooking modern organisms. Consider what you know about trilobites and horseshoe crabs as you write your answer. Evaluate Suppose you are in a river valley. Which two geologic principles could you use to determine whether the rock beds on either side of the valley are the same?
Petrified wood is an example of a A. Which object has the best chance of becoming fossilized? A break, or gap, in the rock record is evidence of 4. Fossilized bird footprints are excellent fossils. Sedimentary rocks are often dated using 6. Matching rock layers in different parts of the same state is an example of 9. According toprocesses that are occurring today are similar to processes that occurred in the past.