If heat rises, why is the center of the Earth filled with hot lava?
142200
The density of it causes it to have more mass, making it have more gravity, meaning it attracts to itself more than anything else on earth pulling it to the center.\n\nMore mass = more gravity.\n\nGravity pulls two objects together. We don't see this because things we see it's too small to notice, but say the earth is attracted to the sun and that's what keeps us in orbit, a black hole is made up of material that is VERY dense and that's why it pulls everything in so strongly, so strong even light doesn't escape. \n\nSo the densest layer of a planet is in the center, and the least dense is on the outer, unless another scientific principle outwieghs that one in application.\n\nImagine a block of iron and a bag of dirt, which would you feel pulling toward the earth stronger?\nYou would percieve the block of iron going toward the surface of the earth stronger than a bag of dirt, but if you think about it it's also moving toward the center of the earth. So that's what happens, the metal is in the middle and the dirt is on the surface.
655694
It cools as it nears the atmosphere, and finally where we are it's cool enough for us to have evolved to ask the question.\n\nIn fact, the crust is maintained at a rather low temperature  - around 50 degrees F all the time - just 50 to 100 feet down or so. After that the temperature starts increasing. At between 18 and 1800 miles down, it's up at around 212 F (boiling point of water) due to pressure of that 18-1800 miles of rock (the range is wide because at some points in the ocean the mantle is closer to the crust). That's where mantle takes over.\n\nThe basic answer is that we're at least 1000 miles from the mantle. So when you say the mantle is "just" beneath the crust, you're talking about a pretty significant distance.
781652
[edit] Atmospheric convection\nIn the case of Earth's atmosphere, solar radiation heats the Earth's surface, and this heat is then transferred to the air by convection. When a layer of air receives enough heat from the Earth's surface, it expands, becomes less dense and is pushed upward by buoyancy. Colder, heavier air sinks under it and is then warmed, expands, and rises. The warm rising air cools as it reaches the higher, cooler regions of the atmosphere and becomes denser. Since it cannot sink through the rising air beneath it, it moves laterally and then begins to sink. When it reaches the surface again it is heated, and is drawn back into the original rising column.\nSo the answer is D
49283
The heat is radiated from the core of the Earth - from the heat buildup from when the Earth was forming - the conversion of gravitational energy to heat.  It is cooler now than when the planets were forming, but it's still pretty dang hot at the core, and that's the heat that warms up the asthenosphere.
168578
As far as I know, magma pressure under the earth bulids and builds and eventually it shoots out as lava.
210093
Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Because it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually some of the magma pushes through vents and fissures in the Earth's surface. A volcanic eruption occurs! Magma that has erupted is called lava. \n\nalso\n\nWhen rock inside the Earth becomes hot enough it melts.\nThis molten rock, or magma, is less dense than the surrounding\nsolid rock.  Just as an object that is less dense than\nwater will float on water, the relatively low density of\nthe magma causes it to rise to the surface of the Earth.\n \nIf the magma contains water and dissolved gasses, when\nthe magma reaches the surface the water and dissolved\ngasses will suddenly expand into steam and gas, causing\na violent eruption.  This is like shaking a coke\ncan and then popping the tab.
640247
The plates consist of an outer layer of the Earth, the lithosphere, which is cool enough to behave as a more or less rigid shell. Occasionally the hot asthenosphere of the Earth finds a weak place in the lithosphere to rise buoyantly as a plume, or hotspot. \n\nOnly lithosphere has the strength and the brittle behavior to fracture in an earthquake. \n\nThe map below locates earthquakes around the globe. They are not evenly distributed; the boundaries between the plates grind against each other, producing most earthquakes. So the lines of earthquakes help define the plates: \n\n\nIn cross section, the Earth releases its internal heat by convecting, or boiling much like a pot of pudding on the stove. Hot asthenospheric mantle rises to the surface and spreads laterally, transporting oceans and continents as on a slow conveyor belt. The speed of this motion is a few centimeters per year, about as fast as your fingernails grow. The new lithosphere, created at the ocean spreading centers, cools as it ages and eventually becomes dense enough to sink back into the mantle. The subducted crust releases water to form volcanic island chains above, and after a few hundred million years will be heated and recycled back to the spreading centers.
840305
The plate which is being subducted under the other plate carries down volatiles with it (carbon dioxide, water etc from in the clay and sediments and rocks and stuff) - and these volatiles allow melting to occur in the mantle at a lower temperature than it would ordinarily do. Some of this melt (magma) may then rise up through the overlying crust (so on the overriding plate, not the one which is being pushed under) and erupt out at the surface as lava... so forming volcanoes.
157169
Convection basically means heat rising.  Geologically speaking, along ocean ridges where tecto0nic plates intersect and the mantle has access to fissures in the tectonic plates magma will continually pour out of the fissures.  The best known of these is the mid Atlantic ridge that runs from the bottom of SouthAmerica to Iceland.  Magma continually spews from this fissure separating the tectonic plates.  The spewing magma forms new ocean floor.  Samples of iron rich minerals taken from the ridge indicate that since the earth's origin there have been pole reversals relatively often (in geologic time).  \n\nThe Pacific rim (part of the circle of fire) is also an example of renewal of ocean floor.  In the pacific rim, the Hawaiian Islands were formed from uprising magma.
703439
the core of the planet is said to be liquid under pressure, hence volcanoes.  the earth isn't hit with enough meteors etc to much influence the mass of the planet, but as the sea-floor dictates, can change in size.  an example is the two of the main plates, I believe in the area of the pacific rim.  these two plates are moving apart, at times exposing the hot core which pushes its mass into the cracks and cementing the 'spread' of the two plates. \nif the other plates of the planet move likewise, then yes, the world could increase in volume, and give rise to a bigger earth, in lieu of magma escaping from our depths, or by areas of the earth becoming less in depth to the core, like an icecube in a glass of water. \nsci fi of years gone by have mentioned the core in relation to volcanoes.  the implication was that the volcano activity was putting extreme pressure on our core, which if not filled by natural forces, would create a partly filled container under pressure.  the natural result was thought at the time was that the earth would explode or implode.
461222
its not just that "heat rises", but that things with lower densities rise above things with higher densities. ice floats in water, helium floats in air, etc.  heat is not an object that can rises, but it is an attribute of particles that affects their density. just like hot air rises, when a flame burns, it produces hot gases that rise. these gases are hot enough to produce light, so we see the light rising with the gases. by the time they have risen above the flame, they are no longer hot enough to give off light, so the flame doesn't go up forever.
58575
These features you're noting, like rivers and oceans, are on the Earth's surface on a layer called the crust.  Lava is molten rock that exists UNDER the crust in a second layer known as the mantel.  The water doesn't 'cool down' the lava because it is seperated by a thick layer of rock.
914286
The ring of fire is caused by plate tectonics.  \n\nIf you look at lava such as the slow moving lava in Hawaii you will see patches of cooled surface.  Some edges grow as lava rises whilst others slide under.\n\nThis is what happens with tectonic plates.  Spreading ridges in the middle of the ocean are where lava is slowly creeping up pushing the continents apart.  Iceland is a place where a spreading ridge has come to the surface causing volcanoes and clearly showing the rift opening.\n\nThis is balanced by subduction zones where the plate slides beneath another.  This causes mountains to be formed and volcanoes to form and erupt.\n\nAnother effect is that as plates slide past each other they can stick and then release suddenly causing earthquakes.\n\nWhilst all this appears dramatic and can be devastating to people living in these areas it is good for the earth and it's population.  The planet stays alive and warm.  Volcanic soils are some of the richest and explain why so many choose to live so dangerously close to volcanoes.\n\nThe process has dramatically changed the earths continents and oceans and been a fundamental part of evolution.
716790
Exactly the same thing as on Earth:  Differential heating caused by the Sun's rays falling on different latitudes of the planet.  This causes the warmer parts of the atmosphere to rise.  Denser atmosphere "blows" in to fill the lower pressure areas (think wind).  If the atmosphere contains materials that can condense(water, vapor, methane, ammonia, etc.) and the temperatures are in the correct range for the atmospheric contents then "weather" occurs.
86122
I was taught in school that it is due to radioactive decay of elements in the core.  That is pure bullcrap.  If it were true, every time a volcano exploded, there would be radioactive toxins spread out across the world.  Others say gravity pushing on the substances create heat and liquification of earth.  This may be somewhat true.  If you put a piece of solid ice in a chamber and put extreme pressure on it, it turns to liquid.  There must be some other source of internal heat generation though.  I have never found a satisfactory answer to date.  I really don't think anyone knows, just like gravity is still a big mystery.
71801
It depends on the volcano.\n\nIf magma - molten rock - is erupted it forms new formations when it cools. On the big island of Hawaii, the volcanic eruptions have added a lot of new land to the island.\n\nIf it is a pyroclastic flow - fast, hot gasses and volcanic debris -  like the one that destroyed Pompeii or Mt. St. Helens, there may not be any new land created and the existing land will be radically altered.\n\nIn general, when a land based volcano erupts, the lava and stone and ash build up around the eruption site into a cone shape.\n\nUndersea volcanos spweing lava also build up, but not in a cone shape. Once the hot rock hits water it starts to cool into large pillow-shaped forms.
79965
Well.. the density of lava is about 2.6 grams per cubic centimeter,\nBetter yet,\nmagma is swollen by heat, becoming lower in density, and rises through the cooler, higher-density material. A volcano is formed and lava flows across the planet's surface.