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“Biological Organization” How living things are organized Core Knowledge www.coreknowledge.org “History of Earth & Life Forms” In your notes, write and answer the following question. • Why is it important to know about the history of the Earth, including how it was formed? Types of Rocks • Review from 4th Grade • 3 Types – Sedimentary – Igneous – Metamorphic http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Rocks/Rocks8.html Sedimentary Rocks Sedimentary rocks made of rock fragments (sediments) or by chemical reactions. The classification of sediments is shown below. http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks6.html Clastic rocks–made of cemented sediments—are classified by their grain sizes. http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks9.html Non-clastic rocks form by chemical precipitation (settling out from a solution.) Limestone is made from calcite, chert from quartz, and halite is rock salt. http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks10.html Biologic sedimentary rocks come from the remains of organic matter. • The most important of these is coal. Anthracite coal results from the greatest pressure and releases the most energy when burned. Other varieties are bituminous and lignite. “Petrified” (permineralized) wood is another organic rock. http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks11.html More about sedimentary rocks • Shale is the most common sedimentary rock • Sedimentary rocks cover about threequarters of the land surface • For more about sedimentary rocks: http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks1.html IGNEOUS ROCKS • Form by solidification (crystallization) of melted minerals Types of Igneous Rocks • Extrusive: Lave hardens to form rocks with tiny crystals and glassy textures. • Intrusive: Beneath the surface, magma hardens to form rocks with easily visible crystal texture. Granite • Light-colored, coarsegrained, no pattern • Mostly quartz, feldspar, mica, and hornblende • Often used for buildings and monuments http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Rocks/Rocks10.html Basalt • Dark-colored, finegrained, extrusive • Formed where lava erupted onto surface • Most widespread igneous rocks • Found locally in the Palisades along west shore of Hudson River, Connecticut River valley http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Slideshow/Igrocks/Igrock2.html Gabbro • Dark-colored, coarsegrained intrusive • Similar composition to basalt—plagioclase feldspar with some pyroxene and olivine http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Slideshow/Igrocks/Igrock8.html Obsidian • Natural volcanic glass • Forms when lava cools very quickly • Usually dark, but small pieces may be clear • Fractures along curved (conchoidal) surface • Used as spear and arrow points, knives http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Slideshow/Igrocks/Igrock7.html Pumice and other igneous rocks • Light colored, frothy (many air spaces) • Same minerals as in granite, but finer in grain size For more about igneous rocks: http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Igrocks/Igro cks1.html Metamorphic Rocks • Formed by heat and pressure changing existing rocks “Foliated” rocks contain much mica and other rocks that produce layering or banding Gneisses and schists are common in New York City and Westchester. http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Metrocks/Metrocks5.htm l Non-foliated metamorphic rocks include marble, which comes from limestone, and quartzite, which comes from sandstone http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Metrocks/Metrocks12.html The Rock Cycle Here is another version of the Rock Cycle http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Metrocks/Metrocks2.html What is geology? • The study of the solid Earth and the processes by which it is shaped and changed. • Geology provides primary evidence for plate tectonics, the history of life, evolution, and past climates. How old is the Earth? • The age of the earth is about 4.6 billion years, based on geologic evidence and radioactive dating. Geologic Time • Geologic time: the time of the physical formation and development of the earth Geologic Time Periods • EON - Longest Two or more geological eras form an Eon, which is the largest division of geologic time, lasting many hundreds of millions of years. ERA Two or more geological periods comprise an era, which is hundreds of millions of years in duration. PERIOD The period is the basic unit of geological time in which a single type of rock system is formed, lasting tens of millions of years. AGE - Shortest An age is a unit of geological time which is distinguished by some feature (like an Ice Age). Important Events of Each Era 1. Precambrian 2. Paleozoic 3. Mesozoic 4. Cenozoic Precambrian Era 4600 to 570 MYA • That time span previous to the Paleozoic that comprises approximately 90% of earth history • earliest forms of life, such as bacteria and blue-green algae; later in the period, invertebrates such as jellyfish Paleozoic Era 544 million to about 230 MYA • Pangaea • invertebrate life, such as trilobites • followed by amphibians, and the beginning of reptiles • simple plants, such as mosses and ferns Pangea • A hypothetical supercontinent that included all the landmasses of the earth before the Triassic Period. Plate Tectonics • from the Latin word tectonicus "pertaining to building“ • is a scientific theory that describes the large scale motions of Earth's lithosphere, which is made of tectonic plates. Mesozoic Era 248 to 65 MYA • Pangaea separates into continents • “Age of Reptiles”; dinosaurs • flowering plants • small mammals and birds Cenozoic Era 65 MYA to the present • Continents move into their current positions • Ice Age & mammoths • Gradual development of mammals, birds and other animals recognizable today • Human civilization Paleontology • a science dealing with the life of past geological periods as known from fossil remains Principle of Uniformitarianism • the process that occurred in the past times produced the same results as similar processes do today Principle of Superposition • younger rocks are deposited on top of older rocks How can scientists estimate the age of Earth? Relative Dating • A method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock Radioactive Dating • Calculating the age of a substance by analyzing the decay of radioactive isotopes. • In other words…scientists measure the amount of particles that have been released by the nucleus of an atom over time. Radioactive Dating Radioactive Decay 1. Naturally-occurring radioactive materials break down into other materials at known rates. This is known as radioactive decay. 2. If a substance is radioactive it is unstable and has lost or gained electrons. 3. Each radioactive isotope has its own unique half-life. A half-life is the time it takes for half of the parent radioactive element to decay to a daughter product. Elements as clocks? • Many radioactive elements can be used as geologic clocks. Each radioactive element decays at its own nearly constant rate. Once this rate is known, geologists can estimate the length of time over which decay has been occurring by measuring the amount of radioactive parent element and the amount of stable daughter elements. Radioactive Dating • The most common form of radioactive dating is carbon dating. How long has there been life on the planet? • Using radioactive dating, scientists have determined that life has been on planet Earth for 2- 3 billion years! The oldest known fossils Stromatolites are the Earth’s oldest known fossils, dating back to over 3 million years. Stromatolites are fossilized layers of sedimentary rock and blue-green algae. Fossils • Fossils are a record of the Earth’s history and past life forms. Types of Fossils • • • • • There are four main types of fossils 1. Mold Fossils 2. Cast Fossils 3. Trace Fossils 4. True Form Fossils Mold Fossils • a fossilized impression made in the substrate. A mold fossil makes a negative image of the organism Cast Fossils • formed when a mold is filled in Trace Fossils • Trace Fossils are also called ichnofossils • Trace fossils may be impressions made on the substrate by an organism: for example, burrows, borings urolites (erosion caused by evacuation of liquid wastes), & footprints. True Form Fossils • True form fossils are the fossilized remains of real animal parts or the actual animal. These fossils can be from animals or plants trapped in ice, tar or amber Extinction • The end of an organism’s existence. • Hundreds of creatures that once lived on the planet are now extinct, including dinosaurs, mammoths, dodo birds, and even modern animals, like the passenger pigeon. Dinosaur Extinction • Dinosaurs became extinct about 65 million years ago. • There are a few theories about dino extinction, but scientists may never know for certain. • Theories include: asteroid impact, climate change, volcanic eruptions, & disease carrying insects The Future of Geology • Yellowstone National Park’s Supervolcano • Yellowstone, like Hawaii, is believed to lie on top of an area called a hotspot where hot, molten rock rises towards the surface. • It is not a matter of if, but when, this supereruption will happen!