The edges of these plates, where they move against each other, are sites of intense geologic activity, such as earthquakes, volcanoes, and mountain building. Plate tectonics is a relatively new theory and it wasn't until the 1960's that Geologists, with the help of ocean surveys, began to understand what goes on beneath our feet. Where is the Evidence for Plate Tectonics? It is hard to imagine that these great big solid slabs of rock could wander around the globe. Scientists needed a clue as to how the continents drifted. Click here for the Scotland story Picture the following in your mind: You have a nine piece jigsaw (now there's a challenge). What do you think will happen to the puzzle? Now let's think back to our plates being created at the mid-ocean ridges, it seems to be a good idea but if this is the only type of plate movement then the world would get bigger and bigger. The floor of the Easter Pacific is moving towards South America at a rate of 9 centimetres per year.
Plate TectonicsQuicktime versionAVI version Animated gifs Last 750 million years: [1.04 MB] [506 KB] [261 KB] Last 750 million years in reverse: [1.04 MB] [506 KB] From 750 mya to the beginning of the Paleozoic: [294 KB] [166 KB] From 750 mya to the beginning of the Mesozoic: [532 KB] [284 KB] [156 KB] From the beginning of the Mesozoic to Recent: [301 KB] [163 KB] [96 KB] All animations built from maps used with the permission of C.R. There are a number of excellent sites dealing with the modern theory of plate tectonics. The Paleomap project at the University of Texas at Arlington.Paleogeography Through Geologic Time by Ron Blakey at Northern Arizona University. Finally, it seems appropriate to mention the Alfred Wegener Institute, the German national research center for polar and marine research, carrying on Wegener's tradition of interdisciplinary earth science. Sources: S.
Plate TectonicsAsk GeoMan... What is plate tectonics? There are really only two processes: one that forms the physical earth, and another that beats up the surface and tears it apart through weathering and erosion. The formational process is called tectonics, and is manifested to those of us living on earth by earthquakes, volcanos, and mountain building in general. The earth is really just a sphere of liquid rock (magma) which has cooled to the solid state where exposed to the coldness of space. plates are moving towards each other, and the crust of the earth is shortened. GeoMan's RCC Continental Drift and Plate Tectonics section GeoMan's Grants Pass High School Geology Home Page GPHS class notes on Continental Drift GPHS class notes on Plate Tectonics: an overview GPHS class notes on Divergent Plate Boundaries GPHS class notes on Convergent Plate Boundaries AskGeoMan: Plate Boundary Summary Click here to ask GeoMan a question Return to Ask GeoMan's Index of Questions Return to GeoMan's Home Page
Earth Floor: Plate TectonicsConvergent Boundaries Places where plates crash or crunch together are called convergent boundaries. Plates only move a few centimeters each year, so collisions are very slow and last millions of years. Even though plate collisions take a long time, lots of interesting things happen. For example, in the drawing above, an oceanic plate has crashed into a continental plate. Are They Dangerous Places to Live? On the other hand, earthquakes and volcanoes occurring in areas where few people live harm no one. Back | NextInternational Tsunami Information CenterSolar-powered sea slug harnesses stolen plant genes - life - 24 November 2008Video: Watch a sea slug eat algae to nab some of its chloroplasts, and the genes that keep them functioning It's the ultimate form of solar power: eat a plant, become photosynthetic. Now researchers have found how one animal does just that. Elysia chlorotica is a lurid green sea slug, with a gelatinous leaf-shaped body, that lives along the Atlantic seaboard of the US. Mary Rumpho of the University of Maine, is an expert on E. chlorotica and has now discovered how the sea slug gets this ability: it photosynthesises with genes "stolen" from the algae it eats. She has known for some time that E. chlorotica acquires chloroplasts - the green cellular objects that allow plant cells to convert sunlight into energy - from the algae it eats, and stores them in the cells that line its gut. Young E. chlorotica fed with algae for two weeks, could survive for the rest of their year-long lives without eating, Rumpho found in earlier work. But a mystery remained. Gene 'theft' Human photosynthesis?
3. Journey Through EarthIn the style of Jules Verne’s book Journey to the Center of the Earth, take your students on a walk, using sidewalk chalk to mark the boundaries between the different ... SummaryIn the style of Jules Verne’s book Journey to the Center of the Earth, take your students on a walk, using sidewalk chalk to mark the boundaries between the different layers inside our planet. After you pass through each layer, tell your students about the layer of the Earth they just traveled through. This lesson was developed by Eric Muller of the Exploratorium Teachers’ Institute. Here you will find a student handout for taking notes during the walk, a teacher cheat sheet and some assessment ideas. Earth's Layers: Layers not drawn to scale. Time10 min introduction35-40 min walk GroupingWhole class Materials A copy of the Earth Journey Handout for each studentA copy of the Earth Journey Teacher Cheat Sheet for yourselfA piece of sidewalk chalk for each student Student PrerequisitesNone Getting Ready Going Further
Convergent boundaryDescriptions The nature of a convergent boundary depends on the type of plates that are colliding. Where a dense oceanic plate collides with a less-dense continental plate, the oceanic plate is typically thrust underneath because of the greater buoyancy of the continental lithosphere, forming a subduction zone. Where two continental plates collide the plates either buckle and compress or (in some cases) one plate delves called subduction, under the other. When two plates with oceanic crust converge, they typically create an island arc as one plate is subducted below the other. Not all plate boundaries are easily defined. Convergent margins A subduction zone is formed at a convergent plate boundary when one or both of the tectonic plates is composed of oceanic crust. An oceanic trench is found where the denser plate is subducted underneath the other plate. Some convergent margins have zones of active seafloor spreading behind the island arc, known as back-arc basins.
Rwanda’s rainforest renewal : National Parks, AfricaWhen choosing Rwanda as a holiday destination, many people are keen to see the country’s rare primates and learn about its dark past. But those who work in the tourism industry are keen to show visitors a new Rwanda. Not one that is dismissive of its history – but one that offers more than museums and gorillas. Related article: Experiences that make time stand still For the last seven years, the Rwanda Development Board (RDB) has been focusing on the rainforest 200km to the west of capital city Kigali in a bid to attract adventurous travellers. Created as a national park in 2004, Nyungwe is full of waterfall treks, colobus monkey spotting and canopy walkways – and thanks to the recently improved road infrastructure from Kigali – is easily accessible. “In the past people would often have stayed in Rwanda for just a few days, perhaps as part of a wider Africa trip,” said Manzi Kayihura, president of the Rwanda Tours and Travel Association.
The 3 basic rock typesAsk GeoMan... What are the 3 basic types of rocks? Just as any person can be put into one of two main categories of human being, all rocks can be put into one of three fundamentally different types of rocks. They are as follows: Igneous Rocks Igneous rocks are crystalline solids which form directly from the cooling of magma. Sedimentary Rocks In most places on the surface, the igneous rocks which make up the majority of the crust are covered by a thin veneer of loose sediment, and the rock which is made as layers of this debris get compacted and cemented together. Clastic: your basic sedimentary rock. Click here for more on sedimentary processes and rocks (RCC). Metamorphic Rocks The metamorphics get their name from "meta" (change) and "morph" (form). Click here to ask GeoMan a question Return to Ask GeoMan's Index of Questions Return to GeoMan's Home Page You are GeoManiac number since April 1, 1997