Goal 5 EOG REVIEW

1. Goal 5 EOG REVIEW The learner will conduct investigations and utilize appropriate technologies and info systems to build an understanding of EVOLUTION in organisms and landforms.

2. Geologic Time • Earth is 4.7 billion years old. • Scientists know about earth’s history because they have studied the fossil record. We arrange this fossil record into a Geologic Timescale. • Geologic timescale: a timeline that organizes the events in Earth’s history. We divide this scale into eons, eras, periods and epochs.

3. Con’t • Eon: the largest group • Era: mass extinctions mark the boundaries between the eras; they are hundreds of millions year long • Period: blocks of time when a unique rock series was laid down; tens of millions of years long • Epoch: divisions of the most recent periods; several million years long

4. Websites for Geologic timescale • http://vulcan.wr.usgs.gov/Glossary/geo_time_scale.html • http://www.geo.ucalgary.ca/~macrae/timescale/timescale.html • Fossils: imprints or remains of organisms that were once alive. They provide evidence for the geologic timescale. • Fossils can be made from the teeth, bones or other hard parts of an organism.

5. Con’t • Fossils form in sedimentary rock. Layers of sediment build up over a dead organism. Over time, pressure causes these layers to turn to rock. The parts of the organism that are buried in the sediment are preserved within the rock.

6. Ways fossils form

7. Con’t

8. Con’t • The position of fossils within sedimentary rock layers has helped scientists to construct the geologic timescale. When layered sedimentary rock is not disturbed by other geologic events, the lowest rock layers are the oldest. Therefore, fossils at the top are from organisms that lived in more recent times.

9. Earth’s history: rocks, fossils, an ice cores • Determining the age of rocks • When studying rocks and fossils, scientists use techniques to determine their absolute or relative ages. • Absolute age: tells the actual age of a rock or fossil or how ago an event occurred, such as the year 1848 or 2500 years ago. • Radioactive dating: a means a measuring the age of a material by comparing the amount of a radioactive form of an element in a rock or fossil with the amount of its decay product.

10. Con’t • Relative age: describes the age of an object or event in comparison to another object or event. Tells you which event is earlier or later (does not give an exact age). • Law of superposition: states that in an undisturbed sedimentary rock layer, older rock layers lie beneath younger rock layers. Oldest sediments must be laid down before the younger ones can pile on top.

11. Con’t • Plate movements can disturb rock layers by folding or turning them. Sometimes a layer can be missing from one area of a rock bed (called an unconformity). Unconformities make it difficult to understand how Earth changed during a specific period of time because the information in them is missing.

12. Con’t • Fossils can be used to determine the geologic history or age of the rocks that contain them. Suppose two similar rocks in different locations contain the same kinds of fossils. The fossils suggest that the rocks were laid down in a similar place and time and later became separated. When the absolute age of a fossil is known, the fossil can be used to identify the approximate age of the rock layer in which it was found.

13. Con’t • Index fossils: is a fossil of an organism that existed for only a short period of time. Trilobites (most common index fossil) lived from 200 million years ago to 500 million years ago. Thus, a rock containing a trilobite must be between 200 million years and 500 million years old.

14. Con’t • Scientists study ice cores to understand how climate has changed on Earth. Ice cores form layers similar to rocks. Lower layers are older that higher layers. Each layer records the concentration of gases in at atmosphere during the time the ice formed.

15. Causes of extinction • The process through which a species disappears from Earth is called extinction. They occur naturally over time. Most often, extinctions occur following a sudden, drastic change in the environment. When sudden changes occur, populations living in the affected area may not be able to adapt quickly enough to survive the change. If the organisms are not able to adapt or find another area in which they can survive, they die.

16. Con’t • Scientists estimate that 99.9% of all species that ever lived on Earth have become extinct. • Mass extinction: occurs when large numbers of species die out in a fairly short period of time. We have had many of them. Each time 50% of all living species living at that time dies out. 65 million years ago the dinosaurs disappeared from Earth. Most scientists agree that cooling of Earth’s climate and a decrease in photosynthesis caused the extinction.

17. Dinosaur Extinction theories • Some scientists believe that the climate change that caused dinosaurs to go extinct resulted from a catastrophic event- the impact of a giant asteroid with Earth. They believe that after it struck wildfires may have produced thick clouds of soot in the atmosphere.

18. Theories con’t • Some scientists believe that the movement of the tectonic plates and an increase in volcanic activity on Earth caused global climate change. As volcanoes erupted, thick clouds of dust and soot entered the atmosphere. • After the mass extinction of the dinosaurs, a new age of mammals began. As old species disappear, more resources such as food and shelter become available.

19. Evolution Theories and Processes • Evolution: a process of change over time. • Charles Darwin developed the most accepted theory of biological evolution in the 19th century. • He proposed that over time, new species developed from pre-existing species. • He described natural selection. Natural selection: most organisms produce more offspring than can survive, organisms compete with each other for resources, some offspring will have traits that make the better able to survive, and beneficial adaptations will be found in more and more individuals in the population.

20. Con’t • Adaptation: a trait that improves an organism’s chance for survival and reproduction. • Geological evolution: how Earth’s surface has changed over time. • In 1912 Wegener observed that the continents on Earth appeared to fit together like a big jigsaw puzzle. This led Wegener to propose that all the continents had once been part of a single landmass that he called Pangaea.

21. Con’t • He believed that the landmass had gradually split apart and the continents moved to their present locations through a process called continental drift. • Theory of plate tectonics: states the Earth’s lithosphere (land) is broken into large sections called tectonic plates that move and change position over time. • The place where two plates meet is called a plate boundary. The movement of tectonic plates relative to each other causes different landforms to form near plate boundaries.

22. Con’t • Convergent plate boundaries: push together; causes land to rise to form mountains • Divergent plate boundaries: pull apart; create new seafloor and undersea mountains called mid-ocean ridges • Transform plate boundaries: slide past each other; causes earthquakes

23. Technological Evolution • Technology evolves in response to societal or business needs. Wartime spurred the invention of the computer. Once people prepared letters on typewriters in the workplace.

24. Evidence of Geologic Evolution • Plate tectonics has moved the continents, changed to distribution of living things, and created landforms such as mountains and islands. • As the continents moved they changed the shape of Earth’s surface. We find evidence for continental drift in the fossil record. Mesosaurus is a reptile that lived 250 million years ago. Scientists have discovered fossils of Mesosaurus in South America and Africa. So it had to have lived when these two continents were connected.

25. Con’t • Earth’s surface is also changed gradually through weathering. Weathering: a process in which rocks are broken down into smaller pieces through the action of wind, water, roots and animals. • Two kinds of weathering: mechanical and chemical • Mechanical: breaks rocks apart without changing their chemical composition. Ex. Water seeping into cracks • Chemical: changes the chemical composition of the rocks. Ex: air, water, salts, and acids react with minerals in rocks forming new substances.

26. Monitoring Earth from Space • Energy from the Sun travels as electromagnetic, or EM waves. • EM waves: a wave that transfers energy through a field. All the waves make up the electromagnetic spectrum. • Each type of EM wave transmits a different amount of energy. This causes them to interacts with objects on Earth in different ways.

27. Con’t • Each type of matter on Earth reflects and absorbs different wavelengths of energy in unique ways. Thus, each type of matter has its own signature, called a reflectance curve. Scientists use the reflectance curve to monitor areas on Earth. The satellites orbiting Earth detect wavelengths of energy on Earth and study them (called spectral analysis.) Scientists can use spectral analysis for studying forests, soils, and water.

28. Using Maps and Remote Sensing • Earth’s surface has many different natural features- from the highest mountains on land to the deepest trenches beneath the sea. These features change over time. Changes on Earth’s surface are also created by human activity. For example, cities and suburbs grow over time, new industrial areas may replace shorelines, forests may be cleared or new forests planted.

29. Con’t • Topography: the study of Earth’s natural and artificial features by surveying and mapping. Earth’s features can be shown on a topographical map. • A topographic map is a two-dimensional model of Earth’s surface. The most important function of a topographic map is to show elevation. Lines on a topographic map that connect areas with the same elevation are called contour lines.

30. Con’t • Topographic maps are created from photographs taken from high above. Through a process called ground truthing, scientists then visit the area that has been mapped to confirm that their maps match what was seen in the photograph and the actual terrain of the area.

31. Con’t • Satellite photographs are a type of remote sensing: a way to collect info about an area without visiting the area. Remote sensing allows scientists to keep track of changes on Earth’s surface. By studying satellite images of an area over time, scientists can monitor land use in that area.

32. Con’t • Remote sensing can monitor urban sprawl. Urban sprawl: the spreading out of city features, such as neighborhoods and shopping districts. Studying urban sprawl can help city planners to predict or manage the future growth of a city. • Remote sensing can also help forest and wildlife professionals manage resources. It can show patterns of logging, how forests grow back over time, and to identify areas of forest that might be a good habitat for certain types of wildlife.