Plate Tectonics ~ Plate Tectonics Theory ~ What Alfred Wegener didn't know... Plate Tectonics: Why do continents drift? Answer: Crustal Plates move due to Sea-Floor Spreading, and because of Convection Currents in the mantle. Advances in SONAR or SUBMARINE technology in the 1960's allowed scientists to understand what was happenig on the Ocean Floor. ~ Sea Floor Spreading ~ Click here: Harry Hammond Hess // SFS with Bill Nye Animation Above: How sonar works. Sound waves bounce off the ocean floor, and then back to the sonar recording device on the ship. Ocean Floor Map Question: Why is the Sea Floor spreading? Answer: Convection Currents in the Mantle are causing Oceanic Crust to separate. Above: Boy from Iceland Above: The Mid-Atlantic Ridge Above: The Global Mid-Oceanic Ridge System The Sea Floor is Diverging (spreading apart) at the Mid-Ocean Ridges: A Mid-Ocean Ridge System Click here: Labeling Sea Floor Spreading at Mid Ocean Ridges - Interactive Below: Subduction Zone Here's the deal... A. B. C. Pre-Plate Tectonics...
Fault creep along the Calaveras in Hollister, California Introduction Hollister, California is located South of the San Francisco Bay area. (Here is a regional map courtesy of Xerox PARC.) In the Bay area there are three major faults, from West to East the San Andreas, the Hayward, and the Calaveras; all are part of the San Andreas fault system. South of the Bay Area the Hayward and Calaveras merge into the San Andreas. What makes Hollister particularly interesting to geophysicists is that from San Juan Bautista (HERE) to just North of Parkfield (HERE) the faults in the San Andreas system are not ``stuck'': instead of moving only during major earthquakes, the usual pattern for faults, they continuously ``creep''. Here is a map showing the approximate active trace of the fault for the part of town covered in our tour. The creep rate apparently varies in an unpredictable way. Hollister has become rather ``yuppified'' over the last decade. Walking Tour Find ``Vista Park Hill'', just NorthWest of downtown. Rogers, T. Sylvester, A. Disclaimer
Daily Grammar Archive - Comprehensive Archive of Grammar Lessons This archive contains links to all of our free grammar lessons and quizzes. You can use this archive to study Daily Grammar at your own pace. Lessons 1-90 cover the eight parts of speech, which are verbs, nouns, pronouns, adjectives, adverbs, prepositions, conjunctions, and interjections. Lessons 91-300 cover the parts of the sentence, such as appositives, predicate nominatives, direct objects, prepositional phrases, clauses, and verbals. Lessons 301-440 cover the mechanics of grammar, which is also known as capitalization and punctuation. Our lessons have been organized by lesson number and by subject. Lessons 1, 2, 3, 4, 5 - Quiz Lessons 6, 7, 8, 9, 10 - Quiz Lessons 11, 12, 13, 14, 15 - Quiz Lessons 31, 32, 33, 34, 35 - Quiz Lessons 36, 37, 38, 39, 40 - Quiz Lessons 41, 42, 43, 44, 45 - Quiz Lessons 46, 47, 48, 49, 50 - Quiz Lessons 51, 52, 53, 54, 55 - Quiz Lessons 56, 57, 58, 59, 60 - Quiz Lessons 61, 62, 63, 64, 65 - Quiz Lessons 66, 67, 68, 69, 70 - Quiz
Earth Science World Image Bank The Earth Science World Image Bank is a service provided by the American Geosciences Institute (AGI). This Image Bank is designed to provide quality geoscience images to the public, educators, and the geoscience community. Click on one of the images below to browse that category or go to the Search Images page for an advanced search. The Image Bank now has over 6,000 images available to search, making it one of the largest sources of Earth Science imagery available on the web! IMPORTANT NOTE: The American Geosciences Institute has stopped issuing commercial permissions for images from the Earth Science World Image Bank.
EarthScienceAnimations Animation: Earth's Atmosphere Lesson 19: Atmospheric Structure contains instruction on the troposphere, the tropopause, the jet stream, the stratosphere, ozone, the production of ozone, the destruction of ozone, chlorofluorocarbons, the stratopause, the mesosphere, the thermosphere, the ionosphere, the exosphere, and the Earth's atmosphere. To begin the animation, click here. You will need to download Macromedia Flash Player to view this lesson. Geysers erupt because they’re all bendy inside University of California at Berkeley volcanologist Michael Manga and student Esther Adelstein built a laboratory geyser to explain how geysers like Old Faithful work. (Roxanne Makasdjian and Phil Ebiner; additional footage by Eric King and Kristen Fauria/University of California at Berkeley) You'll definitely want to check out the video above, because it features a loop-de-loop lab apparatus designed to spew water into the air. But it's more than just a twist on one of those science fair volcano models: The UC Berkeley earth sciences professor who designed it says it demonstrates the basic mechanics of geysers like Old Faithful. Michael Manga and his colleagues report on their findings in the February issue of the Journal of Volcanology and Geothermal Research. Manga's model isn't quite so reliable. Threading temperature and pressure sensors down a geyser hole in the El Tatio region of Chile's Atacama desert. Read More: Did a massive volcanic eruption in India kill off the dinosaurs?
Astronomy Picture of the Day WHO'S ON FIRST? A RELATIVE DATING ACTIVITY MARSHA BARBER and DIANA SCHEIDLE BARTOS PALEONTOLOGY, AND in particular the study of dinosaurs, is an exciting topic to people of all ages. Although most attention in today's world focuses on dinosaurs and why they became extinct, the world of paleontology includes many other interesting organisms which tell us about Earth's past history. Teaching about Earth's history is a challenge for all teachers. In this activity, students begin a sequencing activity with familiar items — letters written on cards. Once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of Earth's history. The complete "Paleontology and Dinosaurs" module takes approximately four weeks to teach. WHO'S ON FIRST? INTRODUCTION Scientists have good evidence that the earth is very old, approximately four and one-half billion years old. Return to top Figure 2-A. WHO'S ON FIRST? Figure 2-B. Return to top Set A Set B
Rock Cycles cycles Rock Cycles Even rocks have a cycle. Rocks are continually circulating in the mantle just below the crust of the earth. They are sometimes thrust up into the crust due to convection currents. Imagine really thick jam slowly cooking in a big pot on a stove. Once on the surface of the earth, rocks cool down. Sample some of the following activities to learn more about rocks and their cycles. Places To Go People To See Things To Do Teacher Resources Bibliography Places To Go The following are places to go (some real and some virtual) to find out about rocks and their cycles. Ayers RockVisit famous Ayers Rock in Australia. Devils Tower National MonumentVisit Devil's Tower in Wyoming. Easter IslandStroll along the beaches of Easter Island. The Formation of the HimalayasVisit the Himalayas. The Geology of the Grand CanyonErosion is part of the cycle of how rocks erode from wind, water, glaciers, and shifts in temperature. Grand Canyon ExplorerVirtually visit the Grand Canyon. How Do Soils Form?
Floating Farms It is fairly straightforward to measure the area of most lakes. Certain satellite sensors, such as the Operational Land Imager (OLI) on Landsat 8, are particularly well suited to the chore because they collect information from several sections, or bands, of the electromagnetic spectrum that can be used to distinguish between water, land, and aquatic vegetation. However, determining the size of Inle Lake poses a special challenge. The second largest lake in Mynamar (Burma) has a unique agricultural system that makes the boundary between land and water remarkably fuzzy. The system, known locally as ye-chan, involves the cultivation of hundreds of hectares of floating “islands” that produce enough tomatoes and other vegetables to drive the region’s economy. Landsat 8 acquired an image (top) of the southern part of Inle Lake on January 25, 2015. According to one study, the area covered by floating gardens increased by 500 percent between 1992 and 2009.
Cat of the Day - Every day a new cat photo and story since 1998. Map of The World - Shaded Relief Faults in Xinjiang Just south of the Tien Shan mountains, in northwestern Xinjiang province, a remarkable series of ridges dominates the landscape. The highest hills rise up to 1,200 meters (3,900 feet) above the adjacent basins, and they are decorated with distinctive red, green, and cream-colored sedimentary rock layers. The colors reflect rocks that formed at different times and in different environments. The red layers near the top of the sequence are Devonian sandstones formed by ancient rivers. The green layers are Silurian sandstones formed in a moderately-deep ocean. The cream-colored layers are Cambrian-Ordovician limestone formed in a shallow ocean. The Operational Land Imager (OLI) on the Landsat 8 satellite captured this view of the Keping Shan thrust belt on July 30, 2013. This part of Xinjiang province has a rich and varied geologic history. When land masses collide, the pressure can create what geologists call “fold and thrust belts.” Another type of fault is visible as well. Instrument(s):
Dog of the Day - Every day a new dog photo and story since 1998.