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Evolution in Organisms and Landforms. Warm-up April 16.
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Warm-up April 16 • In your NB, on page ____, draw a timeline of your life. Please include at least 6 events. Make sure to include at least 2 events from before you were born. This could be a sibling or parent birthdate or anniversary of some kind. (Below is an example for me : ) 1865 1906 1945 1964 1983 1987 Civil Gma Mom Me HS College War Born Born Born Grad Grad Ends
Geologic Time Scale= timeline that organizes the events in Earth’s history
Geologic Time Scale • EON- the largest division of geologic time, divided by Cambrian boundary when the variety of life forms explodes (billions of years long) • ERA- a unit of geologic time that includes two or more periods (hundreds of millions years 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)
Cambrian Boundary/Explosion Divides eons (Phanerozoic and Precambrian) and is when the variety of life forms explodes. Most major animal groups appear for the first time in the fossil record some 545 million years ago on the geological time scale in a relatively short period of time known as the Cambrian explosion. Trilobite
Fossils • The imprints or remains of organisms that were once alive
Fossil Formation • Most in sedimentary rock • Form when layers of sediment build up over a dead organism 2. Over time, pressure causes layers to turn to rock • Parts of the organism that are buried in the sediment are preserved in the rock. **Turn to page 238 in Coach and copy pictures on page ____ of notebook.
Ways Fossils Form • Molds – acids eat away the skeleton or shell and leave an impression (mold) in the rock. • If the mold fills with minerals, it becomes a cast.
Ways Fossils Form • Tracks- Imprints left in mud- later hardens • Petrified- Minerals in plant cells crystallize
Fossils used to find dates of events • Absolute Age- tells the actual age of a rock or fossil or how long ago an event occurred. (ie: year you were born) • Radioactive dating- a means of 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. • Relative Age- when absolute age is not possible, relative age describes the age of an object or event in comparison to another object or event.
Using Fossils to date events • The Law of Superposition- states that in undisturbed sedimentary rock layers, older layers of rock lie beneath younger rock layers. • Copy the drawings on page 243 of Coach onto page _____ of your notebook. • Unconformity- missing a layer in the geologic column or rock bed (a gap in the rock record).
Fossils are Clues • Size, shape, growth patterns, and structures of extinct organisms. • Example- shape of tooth can show whether an animal ate plants, meat, or both. • Extinct- an organism is no longer found living on Earth. • Copy the picture on page 245 of Coach into your NB on page ______.
Half-Life? • So, what is a half-life?
Ice Cores • Ice Cores Layers form like rocks Each layer records the concentration of gases in the atmosphere during the time the ice formed.
Causes of Extinction • Extinction- the process through which a species disappears from Earth • Some occur naturally over time • Most often occurs following a sudden, drastic change in the environment • If organisms can’t adapt or find new location, they die
Natural causes- extinction • Some scientists estimate that 99.9% of all species that ever lived on Earth have become extinct. • Natural Events • Increase or decrease in temperature • Increase or decrease in rainfall • Volcanic eruption • Earthquake • Flooding or drought • Shifting land or sea • Change in food supply • New predator or disease
Mass extinctions • Occurs when large number of species die out in a fairly short period of time • Abundant fossils in the rocks suddenly disappear • Fossils of new species begin to appear in rock layers above (newer rock) • Dinosaurs- 65 million years ago=climate cooled and decrease in photosynthesis • Scientists disagree on what caused climate change
Climate change theories • Asteroid Theory- evidence found in the K-T Layer- rock layer formed between the Cretaceous and Tertiary periods. • Contains iridium- element found in meteorites • Asteroid produced thick clouds of soot? • Rocks hit by asteroid released chemicals that combined with H2O to produce acid clouds? • In either hypothesis, clouds would have blocked sunlight, causing Earth to cool and plants to die. Gradual Theory- volcanic activity- thick clouds of dust and soot.
Humans and extinction • Rate of extinctions are increasing due to human activities • Habitat destruction • Pollution • Overfishing • Over logging • Climate Change • Poaching or overhunting **Humans can help by changing their bad habits and behaviors
Evolutionary Theories and Processes • Evolution- process of change over time • Biological Evolution- theory proposed by Charles Darwin which stated that over time, new species developed from pre-existing species. • Based on his observations of the finch species living on the Galapagos Islands.
Darwin continued • Theory of evolution by natural selection • Most organisms produce more offspring than can survive • Organisms compete with each other for resources, like food and living space • Offspring all similar, but some will have traits that make them better able to survive.(survival of the fittest) • Adaptation- a trait that improves an organism’s chance for survival and reproduction. • Over time, adaptations that benefit the species will be found in more and more offspring of that species- could eventually become new species.
Geologic Evolution • German scientist, Alfred Wegener, observed that the continents looked like they all had fit together as one landmass that he called Pangaea. • Continental Drift- land gradually split apart and the continents moved to their present locations.
Geologic evolution contin. • Theory of Plate Tectonics- Earth’s lithosphere (land) is broken into large sections called tectonic plates that move and change position over time. • Plate boundary- where two plates meet • Movement of plates in relation to each other causes different landforms • Convergent boundaries- plates push together, causing mountains or islands • Divergent boundaries- plates pull apart, creating new seafloor and undersea mountains or on land, volcanoes. • Transform boundaries- plates slide past each other, many times causing earthquakes
Evidence of geologic evolution • Evidence provided by fossils of a reptile called Mesosaurus • Fossils found in South America and Africa • Therefore, when continental drift occurred, the Mesosaurus were carried to two different parts of the world.
Geologic evolution contin. • COLLIDING PLATES • Both plates ocean plates = one plate is pushed under the other (subduction) • A deep canyon or trench forms; over time forms a chain of volcanoes on ocean floor Continental plate + oceanic plate = oceanic plate is denser, so subducts Chains of volcanic mountains form at the edge of the continental plate (Mt. St. Helens is example in Washington) Both continental plates = they buckle and push upward, forming mountains, like the Himalayas ***See pictures in Coach on pages 259-260
Volcanoes and earthquakes • Sudden changes in Earth’s surface • Earthquakes • Pressure builds up between the plates • Compression- pressure builds as plates press against one another • Shearing- plates slide by one another • Tension- plates stretch and pull away from one another • FAULT- crack where movement occurs • Volcanoes- the movement of magma in and around a volcano can also trigger earthquakes.
Ring of fire • High volcano and earthquake activity • Volcanoes- greater than 75% in this area • Hawaii formed from volcanic activity
Geological changes contin. • Weathering- a process in which rocks are broken down into smaller pieces through the action of wind, water, roots and animals. • Mechanical- breaks rocks apart without changing their chemical composition (copy picture on page 263 of Coach) • Plant roots, burrowing animals exert pressure • Rock, sand, soil particles carried by wind or water • Chemical- changes the chemical composition of the rocks. (air, H2O, salts, and acids may react with minerals in rocks to form new substances, which can result in weakened rock)
Technology Evolution • Makes businesses and personal lives more efficient. • Smart Phone- video, audio, phone, weather, clock….unlimited • Copy machines • Laptops • E-readers • Drones • Internet
