* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 1 Course description Geology lab Outcomes
Survey
Document related concepts
Paleontology wikipedia , lookup
Global Energy and Water Cycle Experiment wikipedia , lookup
Large igneous province wikipedia , lookup
Schiehallion experiment wikipedia , lookup
Spherical Earth wikipedia , lookup
History of Earth wikipedia , lookup
History of geomagnetism wikipedia , lookup
Age of the Earth wikipedia , lookup
Geomorphology wikipedia , lookup
Transcript
Introduction to Geology Earth Science web page: www.centralia.edu www.centralia.edu/academics/earthscience/index.html Patrick Pringle Instructor, NSC 318f ppringle via centralia.edu 360360-736736-9391 x550 Websearch: Earth science Centralia Course description Geology lab PHYSICAL GEOLOGY (4) Explore earth materials, processes and structures within a plate tectonics framework: origin and structure of the earth, rocks and minerals, geologic time, fossils and evolution, earthquakes and volcanoes, ocean basins, formation of landscapes, special topics. Learn how to recognize earth materials, features, and structures. Identification of common rocks and minerals; topographic and geologic maps. Outcomes Geology studies active processes of the Earth Improved quantitative reasoning skills as they pertain to geology and solving geology problems Improved spatial reasoning skills as related to geologic processes and materials Develop critical thinking skills in geology Understanding of geologic time Understanding of the interconnectedness of Earth systems Understanding of the scientific method as it pertains to geology Ability to communicate geologic information Mount St. Helens, February 1983 1 Mount Rainier volcano, from the west Mount Hood volcano Tree buried by past lahar …and geology studies past history of the Earth Geologic processes can be hazardous and can profoundly influence humans. Geologists keep discovering new things! Our knowledge of Mount Rainier’s volcanic history has exploded in the past few decades. Geology has become interdisciplinary. These scientists are using the study of tree rings to estimate the age of a geologic landform. Bonneville landslide—dammed the Columbia River in the mid 1400s • Why Study Earth? --We are seeing revolutionary changes in our understanding of the Earth, the environment, and the universe! • Plate tectonics – the Earth’s machine: subduction, accreted terranes, etc-applications to geology of the planets… • Interconnected Earth systems – rock, water, ice, atmosphere, biosphere… • Geologic and environmental history Why study Earth? Chapter 1 topics: 1.1 What is geology? 1.2 Why study geology? 1.3 How do we know … how to study Earth? 1.4 What does the principle of uniformitarianism mean? 1.5 What is the theory of plate tectonics? 1.6 How does the concept of work apply to Earth? 2 Why study Earth? Why study Earth? Earth’ Earth’s surface is covered with soil that supports natural and agricultural plant diversity Earth materials are the source (either directly or indirectly) of all natural resources – Metals, plastics, timber, gemstones, building materials, etc. Why study Earth? Why study Earth? Landforms derived from Earth processes: And the #1 reason why we should study Earth: – Provide the base for regional ecosystems – Have aesthetic value to humans We all live on it! atmosphere Hydrosphere (and Lithosphere cryosphere) (geosphere) biosphere Fig 1.6mt What is geology? ge· ge·ol· ol·o·gy (Greek; geogeo- + -logi) The scientific study of the planet Earth, the materials of which it is made, the processes that act on those materials, the products formed, 1.1 What is geology? The classic divisions – Historical Geology – the study of physical, chemical, and biological processes used to interpret Earth’ Earth’s past development (ex: mountain building, climate change, and the evolution of organisms as preserved in fossils) – Physical Geology – (the subject of this text) and the history of the planet and its life forms since its origin (including human interactions) Glossary of Geology, 2005, Neuendorf, Mehl, Jackson (Eds.) 3 1.1 What is geology? 1.1 What is geology? And where is it practiced? The classic divisions – Historical Geology – Physical Geology – (the subject of this text) arose from study of landforms and how they came to be. Geologists study Earth from one extreme … Today, geology touches on many other sciences Fig 1.2a … to the other! 1.1 What is geology? 2.237 mph 2237 mph 1.1 What is geology? The interior of our Earth is layered. How have we detected and measured these layers?? Fig 1.4 Processes are events that occur over time. This figure shows the different rates of Earth processes. Fig 1.3 One way to diagram the layers is by composition, and another way is by strength of the layers. Why study Earth? Earth is host of the water used for: power, irrigation, consumption, recreation Geologic investigations produce maps and diagrams of Earth’s geologic materials. 4 Why study Earth? 1.2 Why study geology? Geologists map the risks of geologic hazards Earth interacts with humanity – Earthquakes – Volcanoes – Landslides – Floods Assessing the risks of hazards helps to make cities safer, like San Francisco. Fig 1.5 Orting Buried tree in Orting Hazard zones for lahars, lava flows, and pyroclastic flows from Mount Rainier Hoblitt, R. P.; Walder, J. S.; Driedger, C. L.; Scott, K. M.; Pringle, P. T.; Vallance, J. W., 1998, Volcano hazards from Mount Rainier, Washington, revised 1998: U.S. Geological Survey Open-File Report 98-428, 11 p., 2 plates. [Accessed Feb. 11, 2002 at http://vulcan.wr.usgs.gov/Volcano es/Rainier/Hazards/] We can use geologic info to reduce risk to humans! Electron Mudflow ~A.D. 15021502-3 Climate change—What might be the effects on glaciers, fluvial and glacio-fluvial processes, erosion and aggradation patterns and rates, etc? Geologic processes are an intrinsic part of past climate changes 1.3 How do we know … How to study Earth? The Scientific Method (in brief) – Ask questions (based on observations and/or data) – Collect information (data) – Review and analyze data (your own and others’ others’) – State problems – Formulate a hypothesis – Test hypothesis for predictability and repeatability – If tests refute … modify or make new hypothesis – Publish results (refereed scientific journals) Science is a process, not just a bunch of facts! 5 1.3 How do we know … How to study Earth? How do geologists do science? – The scientific method is not a recipe – Different questions/scenarios require modification of the method Field work – long the “standard” standard” of geology Seasonal processes Instrumental/laboratory work Computer simulations Geology is unique because of the scale and nature of its “natural laboratory”! 1.3 How do we know … How to study Earth? The scientific method integrates inquiry, explanation, and testability in understanding natural phenomena. Geologists use laboratory studies less often than some scientists due to the rates and scales of some Earth processes. 1.4 Uniformitarianism The evidence seems to support the premise 1.3 How do we know … How to study Earth? The “Big Picture” Picture” – Theories and Laws of Nature Principles (aka “Laws” Laws”) – universally applicable generalizations that do not necessarily offer explanation Theories – widely accepted explanations of natural phenomena that explain all relevant data e.g. Theory of Plate Tectonics, Theory of Evolution by natural selection, Quantum theory etc Theory – An explanatory system of propositions, general principles or laws, inferred from the phenomena and linking known facts and observations; held to be true until contradicted or amended by new facts or observations (from the Glossary of Geology, 2005) 1.4 Uniformitarianism What is it? What does it mean? – Uniformity of natural processes as old as the Greek philosophers Means that the current processes on Earth obey the same basic physical laws they did “then” then” allowing us to backback-calculate some prior condition. – James Hutton and Charles Lyell (Principles of Geology v1– v1–3, 1830– 1830–35) formalized concept. 1.4 Uniformitarianism A modern earthquake mirrors events past that built mountains like those in the distance. At left - an active Atlantic beach in South Carolina with ripple marks. At right fossilized ripples of a beach millions of years past based on age estimates from radiometric dating. Fig 1.8 top Fig 1.8 bottom Fig 1.9 6 1.4 Uniformitarianism 1.5 What is the Theory of Plate Tectonics? Current perspectives – Not taken literally Early conditions likely differed (temperature, chemistry) Conditions affect rates of processes Early Earth processes likely occurred at different rates than today, although the same physical principles limited them… them… – Is Uniformitarianism predictive? Sort of … Sure: in the future, mountains will wear down and oceans will open and close cause they have before... However, it is less likely that we can predict where and when an earthquake will occur. 1.5 What is the Theory of Plate Tectonics? A “new” new” theory (c. 1960s) The solid lithosphere of Earth is composed of a number of plates. Over time these plates move (processes described later in book) Some plates grow while others shrink, maintaining a balance of forces and area across Earth’ Earth’s surface. 1.5 What is the Theory of Plate Tectonics? Divergent boundary – – – – – contain both continental Others are mainly oceanic crust New crust Crust becoming wider Shallow earthquakes Extrusive volcanism MidMid-ocean ridge system Some plates and oceanic crust Fig 1.10 1.5 What is the Theory of Plate Tectonics? Convergent boundary – – – – – Subducting zone Plate is consumed Deep earthquakes Volcanic chain above Ocean trenches Fig 1.11b Fig 1.11a 1.5 What is the Theory of Plate Tectonics? Transform boundary – – – – Shearing zone Lots of earthquakes Little/no volcanism E.g., California (San Andreas system) Fig 1.11c 7 1.5 What is the Theory of Plate Tectonics? 1.5 What is the Theory of Plate Tectonics? Hot spots – Fixed (sort of) spot of rising mantle plume – Plate moves across – Builds island chain in passing Island chain from hot spots Measurements of plate motions using gps and other geodetic techniques supports the amount of uplift and movement through geologic time measured via radiometric age estimates for rocks. Fig 1.12 1.5 What is the Theory of Plate Tectonics? The theory of plate tectonics = Earth’ Earth’s lithosphere is divided into a number of plates. These plates move, either towards or away from one another, or past each other… other… The interaction of plates along their contact boundaries accounts for the distribution of earthquakes, volcanoes, and mountain belts— belts— and provides a basis for examining most Earth processes and products. 1.6 How does … work apply to Earth? Work requires energy Energy on Earth takes various forms – Stored deep ocean trenches earthquakes volcanoes Fig 1.10 The best evidence for plate tectonics is that it explains so many observations. 1.6 How does … work apply to Earth? Earth is full of active processes – Water flowing in streams – Plate motion – MountainMountain-building … for example These processes involve movement of Earth materials. Thus, by definition, Earth processes are forms of work. 1.6 How does … work apply to Earth? Three modes of heat transfer Only convection causes motion Position Form (e.g., stress, petroleum) – Transformed Motion Heat Fig 1.13 Fig 1.14 8 1.6 How does … work apply to Earth? Sunlight heats the ground. 1.6 How does … work apply to Earth? Within Earth’ Earth’s crust – Cold dense rock sinks in subduction zones. Warmer, molten matter inside rises and convection occurs. – Again, transferring heat and moving mass. – Causes air to rise – Cooler air replaces the rising warm air – Convection occurs, transferring heat and moving mass. Fig 1.15c Fig 1.15b 1.6 How does … work apply to Earth? Potential energy of landscapes ConvectionConvection-driven processes create “high spots” spots” (mountains) Mountains are high relative to the rest of the landscape. This is is potential energy. Water flowing down the mountain, or dislodged rocks or particles, realize this potential as motion. This gradual flattening, erosion, is a powerful force explored (along with others) in Part IV. 1.6 How does … work apply to Earth? Movement of mass within and on Earth’ Earth’s surface is evidence of work. Work requires energy. On Earth, sunlight and internal heat from radioactive decay are the most prevalent sources of energy. Heat is transferred by radiation, conduction, and convection— convection—the last of which is most important in Earth processes. Potential energy is a form of stored energy based on physical position with respect to gravity. When mass falls, flows, or goes downhill, this energy is realized. 9