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Quickie Questions - Earth - Interior/Surface

Date Answered Questioner (age, location) Question Answer
May 4, 2011rin(romania)When uranium atoms split the neutrons clashing eachother release the energy to make the atomic bomb, but how come so much energy from such a small piece of uranium?This is a perfect example of Einstein's equation E = mc2. Although the excess mass m of the un-split uranium is small, the factor c is so large that the energy release E is also large. The physical reason is that uranium is less stable than what it splits into.
February 9, 2011AJ What is pyrite? Is there nickel in it?Pyrite is a mineral containing iron and sulfur (but no nickel). It has a shiny, golden appearance. It is known as "Fool's Gold" since it is sometimes mistaken for real gold.
February 5, 2010Valerie (Texas/ USA)What is the mass of the Asthenosphere and the Lithosphere?The mass of the lithosphere is 1.365 x1023 kg or 2.18 % of earth's mass. More information can be found here.
October 16, 2009cynthia (california)What is the crust made up such as iron or nickel?The oceanic crust is 5 km (3 mi) to 10 km (6 mi) thick and is composed primarily of basalt, diabase, and gabbro. The continental crust is typically from 30 km (20 mi) to 50 km (30 mi) thick, and is mostly composed of slightly less dense rocks than those of the oceanic crust. Some of these less dense rocks, such as granite, are common in the continental crust but rare or absent in the oceanic crust.
August 10, 2009Jordan (New York)How long does it take for sedimentary rock, that is already in the soil, to sink into the earth's interior?The transformation of one type of rock in other is continuos. The process by which rocks are made and destroyed is called the rock cycle. This cycle runs over millions of years, in what is called the Geologic Time. More information on this topic can be found in our web page Rock and the Rock Cycle.
February 26, 2009BRENDON (SAUDI ARABIA)HOW IS A VOLCANO FORMED?Volcanoes form when hot material from below rises and leaks into the crust. This hot material, called magma, comes either from a melt of subducted crustal material, and which is light and buoyant after melting, or it may come from deeper in the interior of a planet and is light and buoyant because it is *very* hot.
February 25, 2009kendra (New jersey/amarica)what would be the tottal percentage of all of the other elements found in the earths crust other then the top 8"From our web page Elements in the Earth’s Crust: Even though there are 92 elements that are naturally found, only eight of them are common in the rocks that make up the Earth’s outer layer, the crust. Together, these 8 elements make up more than 98% of the crust. The 8 most common elements in Earth’s crust (by mass): 46.6% Oxygen (O) 27.7% Silicon (Si) 8.1% Aluminum (Al) 5.0% Iron (Fe) 3.6% Calcium (Ca) 2.8% Sodium (Na) 2.6% Potassium (K) 2.1% Magnesium (Mg)
February 6, 2009Jeana (California)What is a large chunk of the earth's crust called?Tectonic plates are made the crust and upper mantle. The movement of material deep within the Earth may cause these plates to move slowly over the Earth’s surface.
January 30, 2009Bridget (massachusetts)how deep is the earths crust?Crust, the upper layer of the Earth, is not always the same. Crust under the oceans is only about 5 km thick while continental crust can be up to 65 km thick. Also, ocean crust is made of denser minerals than continental crust.
November 12, 2008Dori (CA)What are the main elements that are found in the inner and outer core? My project is due todayThe inner core is a solid metal core made up of nickel and iron (1200 km diameter). The outer core is a liquid molten core of nickel and iron.
November 6, 2008brandy (md)how far is the outer mantleEarth’s Shallow Mantle reaches up to 400 km of depth, followed by a Transition Region (400 to 650 km of depth) and the Lower Mantle (up to 2 700 km of depth).
September 11, 2008saudaa (South Africa)in which layers of the earth's crust do the elements that make up the crust exist?
its urgent!
The thin silicate rock material that make up the crust is evenly distributed along the crust.
September 4, 2008Jovanni (Philippines)How did you know about the core was in the middle of the earth. how did you know the core's components if you,scientist had never seen or went inside the earth.I will let a specialist to answer your question. Please, visite this page for an exhaustive answer to your question.
August 14, 2008anna (new york)how many volcanoes are there in the world?For volcanologists, "active" means that the volcano have the possibility of erupting again. The Smithsonian Institution uses this definition in their web page Global Volcanism Program, and lists about 1300 active volcanoes, but these figures do not include the large number of eruptions (and undescribed volcanoes) on the deep sea floor.
May 28, 2008jessica (u.k)what is a earthquakeEarthquakes happen as large blocks of the Earth’s crust move suddenly past one another because of the force of plate tectonics. These blocks of the Earth’s crust meet at cracks called faults. Sometimes those pieces do not slide smoothly past one another. There can be friction along the fault – jagged edges that snag the blocks of rock. This makes it difficult for them to move past each other. Sometimes they get stuck together temporarily. When the pieces of rock overcome the snags, energy is released. The release of energy causes shaking at the ground surface. See our page Why Do Earthquakes Happen? for more information.
May 23, 2008menna (egypt)how we know about the rocks which inside the earth but iknow that we cannot go inside the earth if we do that we will dieThe rocks are permanently cycled through the Rock Cycle. However, to study the interior of our planet scientists should rely on indirect information, like the earthquake waves that travel through the earth, or the study of rocks from the interior of the planet that are brought to the surface by volcanic eruptions.
May 2, 2008wendy (Philippines)What are the different minerals found in the three layers of the earth?The core is composed mostly of iron (Fe) and about 10% sulphur (S). The mantle, which is composed of iron (Fe), magnesium (Mg), aluminum (Al), silicon (Si), and oxygen (O) silicate compounds. The crust is composed of the least dense calcium (Ca) and sodium (Na) aluminum-silicate minerals.
April 3, 2008Adriana (New mexico)what percent of the Earth is covered by mountains? please respond. i have a project due next weekThe water surface takes about 70 percent of earth's total surface area while the land only takes 30 percent. From this percentage, 20% corresponde to mountains.
April 2, 2008Adriana (New mexico)what percent of each contenent is covered by grassland?Please, visit our web page Grassland Ecosystem for information on this topic.
March 12, 2008Monica (NJ)What is Earth made up of ?The Earth's interior consists of rock and metal. It is made up of four main layers: 1) the inner core: a solid metal core made up of nickel and iron (1200 km diameter) 2) the outer core: a liquid molten core of nickel and iron 3) the mantle: dense and mostly solid silicate rock 4) the crust: thin silicate rock material
February 6, 2008Sylvia (Illinois/United States)How hot is the mantle inside Earth?The temperature of the mantle can reach up to 3700°C/6692°F.
January 10, 2008Brent (Rosebud)What are the surface conditions on Uranus compared to earth????The Giant planets do not have the same layered structure that the earthlike planets do. Their evolution was quite different than that of the earthlike planets, and they have much more gas and ice inside. Uranus's interior is primarily made of methane ice. In contrast, Earth's interior is divided into four layers, which is typical of rocky planets. Each layer has different characteristics and is made of different elements and minerals.
December 21, 2007tyreon (chicago, il)What are some exampales of landform ? name 3Landform is any feature of the surface having a distinct shape and origin. Landforms include major features such as continents, ocean basins, plains, plateaus, and mountain ranges, and minor features such as hills, valleys, slopes, drumlins, and dunes.
December 21, 2007Anissa (GA)What os the aproximate temperature of the amntle??????In the mantle, temperatures range between 500°C-900°C (932°F-1,652°F) at the upper boundary with the crust, to over 4,000°C (7,200°F) at the boundary with the core.
December 21, 2007brissa (CO)what animals live in the lithosphere?The lithosphere is the solid part of our planet. It has two parts, the crust and the upper mantle. The crust is Earth's outermost layer. Therefore, all living things habit there.
December 12, 2007Madalynn (oregon)what is the temperature of the asthenosphere and the lithosphereThe asthenosphere is at very hot temperatures of about 1600 C. The base of the lithosphere occurs where the temperature reaches about 600ºC.
December 10, 2007nikki (ga)what is an organic metamorphic rockAny rock can become a metamorphic rock; it only has to be moved into an environment in which the minerals become unstable. On the other hand, organic sedimentary rocks are formed from organic matter or organic activity. If an organic sedimentary rock suffers metamorphism, we have an organic metamorphic rock.
December 10, 2007fianna (America)what terms refers to features of Earth's surface , such as mountains and valleys?There are diffrent disciplines that study our planet: Geodesy: The science of determining the size and shape of the earth and the precise location of points on its surface. Geodetic: Referring to the determination of the size and shape of the earth and the precise location of points on its surface. Geology: The study of the planet earth -- the materials it is made of, the processes that act on those materials, the products formed, and the history of the planet and its life forms since its origin. Geomorphology: The study of the character and origin of landforms, such as mountains, valleys, etc. Geophysics: The study of the earth by physical methods. From these definitions, it is geomorphology the one closer to your question.
September 19, 2007meera (Qatar,doha)what is crust , core,mantle ?They are the layers of our planet interior. The Earth's interior consists of rock and metal. It is made up of four main layers: 1) the inner core: a solid metal core made up of nickel and iron (1200 km diameter) 2) the outer core: a liquid molten core of nickel and iron 3) the mantle: dense and mostly solid silicate rock 4) the crust: thin silicate rock material
July 20, 2007Elizabeth (New zealand)How deep onto the earth is the core I already know that it's 4150C* but someone said that no one knew the answer?Earth has a diameter of 12,756 km (7,972 mi). The Earth's interior consists of rock and metal. It is made up of four main layers: 1) the inner core: a solid metal core made up of nickel and iron (1200 km diameter) 2) the outer core: a liquid molten core of nickel and iron 3) the mantle: dense and mostly solid silicate rock 4) the crust: thin silicate rock material From the values of the diameters of our planet and of the core, it is at about 6000 km deep.
July 18, 2007karl (scotland)what liquid surounds the solid core of our earthThe Earth's interior consists of rock and metal. It is made up of four main layers: 1) the inner core: a solid metal core made up of nickel and iron (1200 km diameter) 2) the outer core: a liquid molten core of nickel and iron 3) the mantle: dense and mostly solid silicate rock 4) the crust: thin silicate rock material.
July 3, 2007slyvia (malaysia)15% of what is on the earth's surface?Grasslands/savannas are one of the Earth's major ecosystems. The estimates of the amount of the Earth's land surface covered by them vary considerably, but almost all scientists consider a minimum of 15%.
May 11, 2007Shazia (Canada)Since energy is not created or destroyed, what is the source of energy of the Earth's core? If the source of the energy was trapped by gravity during the formation of Earth; isn't this source a limited supply and will this source of energy run out one day? When if runs out what will happen?The internal heat energy of our planet, which drives plate-tectonic motion, earthquakes and volcanic eruptions among others, was much greater in the early stages of the Earth having accumulated rapidly by heat conversion. The three main processes responsible associated with the accumulation were (1) extraterrestrial impacts, (2) gravitational contraction of the Earth's interior, and (3) the radioactive decay of unstable isotopes. All were most intense during the beginnings of the Earth's history. For a description of the processes, visit The Earth's Furnace.
May 10, 2007Jemima (Georgia)How do plates form valcanoes?The Earth's surface is formed by a number of shifting plates. These plates move relative to one another above a hotter zone. Most of the world's active volcanoes are located along the boundaries between shifting plates, from where plasma from below could escape.
May 5, 2007Jessica (Hong Kong)What are the main elements/minerals that make up the earth's core? (With percentages please.)The Earth's interior consists of rock and metal. It is made up of four main layers: 1) the inner core: a solid metal core made up of nickel and iron (1200 km diameter) 2) the outer core: a liquid molten core of nickel and iron 3) the mantle: dense and mostly solid silicate rock 4) the crust: thin silicate rock material. More information in our web page Surface and Interior of Earth and the links therein.
April 19, 2007Sarah (Pa)what is erosion and how does it happen?Erosion is the displacement of solids (soil, mud, rock and other particles) by ocean currents, wind, water, or ice by downward or down-slope movement in response to gravity. Starting with our page Step 1: Breaking Rocks Apart you will be able to follow the different processes that transforms rocks in to sediments.
April 13, 2007joy (california)what is dolomite uses and colorsDolomite color is often pink or pinkish and can be colorless, white, yellow, gray or even brown or black when iron is present in the crystal. It is used in some cements and as a source of magnesium. Fore more in depth information, visit the web page DOLOMITE.
April 13, 2007Melissa (Albany, New York)How is sedimentary rocks formed?Sedimentary rocks are formed at the surface of the Earth (including the bottom of the sea, rivers, lakes, etc.) from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material)
April 7, 2007Kayla (West Liberty)Why is the crust important, or what is its there for?While the crust is very thin in comparison to the other three layers (only about 8 km, 3-5 miles thick under the oceans and about 32 km, 25 miles thick under the continents, it is the layer where we lived!
April 7, 2007sara (Ill usa)why is the earth's crust important?While the crust is very thin in comparison to the other three layers (only about 8 km, 3-5 miles thick under the oceans and about 32 km, 25 miles thick under the continents, it is the layer where we lived!
March 30, 2007C Blue ( Tx)How plates move to cause continents to drift?Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again. More information at our web page How do plates move?.
March 26, 2007melevesi (vaini, tonga)why is lava red?The color of lava depends of its temperature. Initially, when it is between 1000-1150 oC is bright orange. The it cools to 800-1000 oC, and is bright red, then to dark red (650-800 oC), and to brownish red (500-650 oC).
March 20, 2007Nichole (Maryland, US)My 5 year old son is learning about volcano's in school. He would like to know "How do volcano's stay hot?". Is this something that you can help me answer? I hope so. I have searched the net and found nothing that directly answers this question for him. Thank you from the mom of a very inquisitive child!Volcanoes form when hot material from below rises and leaks into the crust. This hot material, called magma, comes either from a melt of subducted crustal material, which is light and buoyant after melting, or it may come from deeper in the interior of a planet and is light and buoyant because it is very hot. More information in our page Volcano Formation and the links therein.
March 20, 2007Mariah (Michigan/USA)What is the difference between a nonfoliated rock and a floiated rock and how are they formed?Foliated rocks are identified by their rock cleavage. When they break, form uniform thin pieces. They are metamorphic rocks, formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. For more information about rocks, visit our page Rock Cycle .
February 25, 2007celina (philippines)what are the topics to be discussed in lithosphere?The tectonic plates are made up of Earth’s crust and the upper part of the mantle layer underneath. Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep. MOre information in our web page The Earth's Crust, Lithosphere and Asthenosphere .
February 24, 2007Shaheen (Kenya)i need to explain to a 7 year old child what earth Lithosphere is so please give me a brief discription. thnksThe plates that fit like puzzle pieces around the Earth are made of Earth’s crust and the upper part of the mantle layer. Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep.
February 24, 2007julianna (Alabama)what causes the Earth's mantle to flow?The intense heat in the Earth’s core causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again. These convection currents causes the mantle to flow. MOre information at our web page How do plates move?.
February 22, 2007Paul What is the Great Global Rift?The Great Global Rift is formed by the deep canyons that split the network of underwater mountain ranges known as the global mid-ocean ridge. Hot magma emerging from underneath the sea floor, seeps into the canyons, filling them with lava, and, as the lava cools, pushes the ocean crust away form the ridge creating new sea floor that moves away from the ridge on both sides. For more information, visit our page Plate Tectonics.
January 23, 2007Justin (Tennessee)What facts are there about the Earth's surface?There are many different types of features on Earth’s surface due to the complexity of our planet. The surface is unique from the other planets because it is the only one which has liquid water in such large quantities. Water forms some features of Earth's surface such as rivers, oceans, beaches and lakes. Other surface features, such as mountains, earthquakes and volcanoes, are formed when large pieces of the Earth’s outer layer move slowly by plate tectonics. More information about our planet interior and surface can be found at our web page Earth.
January 23, 2007Rebecca (England)what temperature is the earths crustCrust is the upper layer of the Earth, and it is not always the same. Crust under the oceans is only about 5 km thick while continental crust can be up to 65 km thick. Also, ocean crust is made of denser minerals than continental crust. The temperatures of the crust vary from air temperature on top to about 1600 degrees Fahrenheit (870 degrees Celcius) in the deepest parts of the crust.
January 21, 2007Jenny (WA , United States)How do Plate Tectonics move?Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle called the asthenosphere. The asthenosphere is solid even though it is at very hot temperatures of about 1600 C due to the high pressures from above. However, at this temperature, minerals are almost ready to melt and they become ductile and can be pushed and deformed like silly putty in response to the warmth of the Earth. These rocks actually flow, moving in response to the stresses placed upon them by the churning motions of the deep interior of the Earth. The flowing asthenosphere carries the lithosphere of the Earth, including the continents, on its back. For more information, please visit our page The Earth's Crust, Lithosphere and Asthenosphere.
January 21, 2007vanessa (Yuma/Az.)Can you please give me about 4 charactoristics for each layer?(Crust, Asthenosphere, Lesthosphere,Upper Mantle, Lower Mantle, OuterCore and the InnerCore)Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle called the asthenosphere. The asthenosphere is solid even though it is at very hot temperatures of about 1600 C due to the high pressures from above. However, at this temperature, minerals are almost ready to melt and they become ductile and can be pushed and deformed like silly putty in response to the warmth of the Earth. These rocks actually flow, moving in response to the stresses placed upon them by the churning motions of the deep interior of the Earth. The flowing asthenosphere carries the lithosphere of the Earth, including the continents, on its back. For more information, please visit our page The Earth's Crust, Lithosphere and Asthenosphere.
January 14, 2007brooklyn (us california)what is a spreading centerFrom the Ocean Institute-Science Glossary:

Spreading Center: Where two or more tectonic plates move away from each other, exposing hot magma to the surface. The magma hardens and becomes basaltic crust.
December 13, 2006Sammie (Texas)Can you give me some facts and examples on metamorphic rocks?The rocks are classified in three groups: Igneous rocks: formed from the cooling and solidification of magma. Sedimentary rocks: formed at the surface of the Earth from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material) Metamorphic rocks: formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. Example of metamorphic rocks are schist and gneiss rocks.
December 9, 2006Julissa (united states of America)Is the lithoshere and athenoshere part of the crust or mantle?Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle called the asthenosphere. The asthenosphere is solid even though it is at very hot temperatures of about 1600 C due to the high pressures from above. However, at this temperature, minerals are almost ready to melt and they become ductile and can be pushed and deformed like silly putty in response to the warmth of the Earth. These rocks actually flow, moving in response to the stresses placed upon them by the churning motions of the deep interior of the Earth. The flowing asthenosphere carries the lithosphere of the Earth, including the continents, on its back. For more information, please visit our page The Earth's Crust, Lithosphere and Asthenosphere
December 6, 2006Leona (Ohio/USA)what does the earth and its inner cores look like?The Earth's interior consists of rock and metal. It is made up of four main layers: 1) the inner core: a solid metal core made up of nickel and iron (1200 km diameter) 2) the outer core: a liquid molten core of nickel and iron 3) the mantle: dense and mostly solid silicate rock 4) the crust: thin silicate rock material For more information visit our page Earth's Interior
November 27, 2006Taylor (Wisconsin)What is a metomorphic rock?
I need a definition
Metamorphic rocks are formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed.
November 12, 2006Araine (Canada)Can you tell me about Rock Cycle and Types of rock? Or if you want explain it to me. PLz.The rocks are classified in three groups: Igneous rocks: formed from the cooling and solidification of magma. Sedimentary rocks: formed at the surface of the Earth from the accumulation of sediments (fragments of rocks, minerals, or animal or plant material) Metamorphic rocks: formed within the Earth's crust when other rocks are subjected to pressures or heat so intense that they are completely changed. Almost all of the rock that we have on Earth today is made of the same materials as the rocks that dinosaurs and other ancient life forms walked, crawled or swam over. While the stuff that rocks are made from has stayed the same, the rocks themselves, have not. Over time rocks are recycled into other rocks. Moving tectonic plates are responsible for destroying and forming many different types of rocks. For more information about Rock and the Rock Cycle visit this page.
October 23, 2006Zac (W.A.)how do volcanoes form?Volcanoes form when hot material from below, called magma and gathered in a magma chamber, rises and leaks into the crust. For more interesting information about volcanoes, visit our webpage Volcano Formation
September 9, 2004Alex(Tennessee/USA)Why do they not just call magma and lava the same thing?Scientists like to be very specific especially when naming things. You're right in thinking magma and lava are the same stuff - it's a matter of where that stuff is found. Molten rock below the surface of the Earth that rises in volcanic vents is known as magma, but after it erupts from a volcano it is called lava.
December 2, 2003Brian(Pennsylvania, USA)Is pyrite an igneous, metamorphic or sedimentary rock? Thank you for your response.That's a hard one, but the answer is actually none of the above! Pyrite is actually a mineral - nonsilicate mineral to be more exact.
December 2, 2003Andrea (ARIZONA/UNITED STATES)WHAT'S CATENA?CATENA is a science journal about Geoecology. Geoecologists study different ecosystems and look at change within the ecosystem. That change can be movement of soil or water. Please note that articles in journals like CATENA are written by scientists for the science community (and may not be light reading for most of us!).
August 5, 2002Chloe (Phillipines)What are possible Coastal Changes and what happens if there is movement on the Earth's Crust?Coastlines can change in many different ways but it usually takes a long time. For instance a coast that is made of sandy beaches can change as ocean currents move the little sand grains to other places.

There is movement on the Earth's crust all the time! The Earth's crust is divided into many large plates and the plates are always moving. They move so slowly we can't usually feel them move unless they crash into each other or slide by each other. That's when earthquakes happen!

July 2, 2002Jody (New Zealand)Why do mountains look blue?The mountains may look blue if they are rocky and the rocks are somewhat blue in color, but they may look blue because they are far in the distance. The mountains look blue when they are far away because of the our atmosphere.

Sunlight bounces off air particles and bits of dust floating in the air. Sunlight is made up of all colors. When they are all together, all the colors appear white, but when they hit air particles, they separate into the different colors, scattering in all directions. Blue light scatters more than red orange, and yellow light, so more blue light reaches our eyes than other colors. This means that to look at something that is very far away, like a mountain range, we need to look through a large amount of air particles and blue scattered light that sit front of it.

August 6, 2001Kim (New Jersey, USA)If we believe that the Moon formed from the Earth, how do we explain the existence of Armalcolite, which is not found on Earth?Actually, armalcolite has been found on Earth in several locations, including Smoky Butte, Montana, Greenland, Ukraine, and in South African diamond mines.

Of course, the theories on how the Moon formed are just that - theories!

August 3, 2001Emma (England)How big would the circumference of the world increase if you laid a row of bricks 4 inches thick all the way around?Circumference is simply the diameter multiplied by pi (3.14, roughly). Laying bricks 4 inches thick all the way around the Earth would increase the Earth's diameter by 8 inches, so the circumference would increase by 8 times pi, which is around 25 inches.
August 3, 2001Melissa (Missouri, USA)What is the driest and hottest place on Earth?The place with that distinction is the Sahara desert. Parts of that area have been known to get to over 130 degrees Fahrenheit, and the world record for temperature (in the shade!) is 137 deg F, set in Libya. Hot!!!
July 11, 2001Emma ( Alabama, USA)What are sedimentary rocks?Sedimentary rocks are those formed from sediments. The term "sediments" is the general name for fragmented rock particles of different sizes. Sediments can be composed of clay, silt, sand, or gravel. When many layers of sediment are deposited (for example, at the bottom of a lake), the bottom layers turn slowly to rock. The rock formed is sedimentary rock. The grains that compose a sedimentary rock can usually be seen with the naked eye. Sandstone and gympsum are types of sedimentary rocks. I've always found this Rock Hounds page fun!
June 15, 2001Jenny (England)In which metal is the Earth's core rich in?The inner core (solid part) of the Earth is made of a Iron-Nickel alloy. The density here is 1017 lb/cubic foot (13,000 kg/m^3) or about 13 times the density of water. The outer core of the Earth (liquid part) is made of an Iron-Sulfur mixture. The density here is 950-770 lb/cubic foot (12200-9900 kg/m^3).
February 5, 2001WK (Singapore)How are deserts formed?Here's a page on desert ecosystems.
October 30, 2000Rachael (England)What is the approximate temperature of the center of the earth?The temperature of the core of the Earth increases rapidly up to 9,000 degrees Fahrenheit.
September 26, 2000Maurice (Texas, USA)From space, Earth looks blue and white. Why?The blue color is the ocean, and the white color is cloud cover! You can also see other colors like brown and green that make up the solid Earth.
June 19, 2000Sukhi (Canada )Why is the earth still considered an 'active' planet?

The Earth is an active planet because it is still forming. Volcanic eruptions and material spewing up from the ocean floor is proof that the Earth is still very busy underneath the surface. As long as this process continues, the Earth will be considered active.

June 8, 2000Andrew (Minnesota, USA)How hot is molten lava as it erupts from a volcano?

Lava temperatures can differ from volcano to volcano. Temperatures have been measured as high as 2000 degrees Fahrenheit. Ouch, that's hot!

May 15, 2000Kate (Australia)How do Glaciers shape the Earth's surface?

Many years ago, glaciers traveled around the globe. They dug into the Earth as they floated around and created holes that later became lakes!

Glaciers also moved sand and other materials around. In certain areas of Michigan, you can find soils that were brought there by glaciers.

May 2, 2000Shameema (Singapore)Which is the shallowest sea in the world?The Sea of Azov is the shallowest sea in the world. Its deepest depth is 46 feet.
April 20, 2000Brendan (New Jersey, USA)What are the eight elements that make up approximately 98% of the Earth's crust?The most abundant elements in the Earth's crust are: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Magnesium and Potassium.
April 20, 2000-- (USA)Why is the outer core of the Earth a liquid and the inner core a solid?

Both the inner and outer core are very hot, reaching temperatures near 7,000 degrees Celcius. So why is the outer core liquid and the inner core solid?

The difference is in pressure. The outer core only has the mantle, crust and atmosphere pressing down on it. That pressure is low enough for the hot temperatures to be dominant. In other words, the outer core stays a liquid.

However, the inner core has all the weight the outer core experiences, plus the added weight of the liquid outer core! The pressure is so great, that the inner core can't melt!

April 11, 2000Steve (Oklahoma, USA)if I were to dig a straight line from where I live, Tulsa, Oklahoma, straight through the core of the Earth, where would I be?Looks to me like you would be right smack in the middle of the Indian Ocean.
March 20, 2000Jennifer (Ohio)What is the most abundant element in the Earth's crust?Aluminum (Al) is the third most abundant element in the earth's crust, after oxygen and silicon...which makes it the most abundant metal in the earth's crust. It is usually found as an aluminosilicate in soils.
March 2, 2000Michael How did scientists decide what the Earth's structure is?Scientists have determined the structure of the Earth through many methods. Different qualities of the Earth, such as the fact that it has a magnetic field, have been used to figure out some of its composition.

The main clue for scientists has been the behavior of seismic waves, waves caused by Earthquakes. Two types of seismic waves that travel through the Earth are P waves and S waves. S waves cannot pass through a liquid, and P waves can but are refracted when moving between liquids and solids. So, scientists use this information and knowledge that S waves can only be observed on the same side of the Earth as an Earthquake occured on, and P waves can make it to the far side, but there is a predictably sized dohnut shaped area called a shadow zone, where no P waves can be measured.

What this tells scientists is that there is an outer core which is liquid (blocking S waves), and a solid inner core determined by differences in where P waves are refracted.

March 2, 2000Leighann (MI, USA)How many square miles of the Earth's surface is land in proportion to water?The world ocean has an area of about 139,400,000 sq mi (361,000,000 sq km). This is about 71% of the Earth's surface, pretty substantial.
November 29, 1999Justin (Arizona, USA)what is the lowest point on earth that is on dry land?The lowest point on Earth is on the shore of the Dead Sea in Asia--1,339 ft. below sea level. The highest point is also in Asia--Mt. Everest, at 29,028 ft. above sea level.
November 17, 1999Micaela (Oregon, USA)Why (or what causes/caused) the Earth to be layered? Is it just the difference in density?Actually, yes! When the Earth was forming it was very hot. Most of the contents was liquid. Something that is more dense than another will separate and make a layer below the less dense material.You can see this by pouring oil into a cup with water!

Iron and Nickel were the densest, so they sank to the middle to form the core. Lighter elements, like Magnesium, are in the mantle. Finally, the least dense materials stayed on top!

May 25, 1999Carmen (Australia)What are sedimentary rocks used for?Sedimentary rocks can be used for a number of things. Sedimentary rocks form layers or stratifications. Each layer is layed down during a certain time period, so sedimentary rocks can be used to tell the geological record of an area. Scientist can tell when an organism lived through which layers its fossils are in. It's almost like looking back in time, pretty neat. Sedimentary rocks can also be quite beautiful. Take a look at this picture .
May 13, 1999Andrew(Pennsylvania,USA)Why does freely draining water spin in one direction above the equator and the opposite direction below the equator?This is one of those questions that seems simple, but scientists still can't totally agree. Some believe that the rotation of the Earth forces the water in a certain direction. However, it takes time for the force to actually work. We all know it only takes a few minutes for the water to go down the drain, so it doesn't make sense that the rotation causes it. Instead, many scientists believe that tubs, sinks and the rest are all made to force the water that way. Everyone expects the water to go in a certain direction, so companies make their products work that way!
May 6, 1999Tim (Michigan, USA)If the earth contains liquid rock in the form of lava, what contains this molten rock? Why doesn't it melt whatever is containing it? How can there be such vast temperature differences between the earth surface and its core? Why doesn't diffusion operate to equal out the temperatures?The Earth is made of rock, which is granite and basalt, and molten metals such as iron and nickel. Although the inner core can reach temperatures up to 7000 F, this heat has to travel 7000 miles just to make it to the rock! By then, the temperatures are cool enough so as to not melt the rock. The temperature difference is caused by the slow heat transfer from the core to the surface. Also, heat is radiated away into the atmosphere at a quicker rate, keeping the temperatures lower.
May 1, 1999Aaron (New York, USA)Where did earth's water come from?It used to be thought that the Earth's water came from sources on the Earth such as volcanic eruptions. Some water does come from volcanic eruptions, but it is now thought that most of the Earth's water came from comets which hit the Earth. Sin ce comets are made of ice, it is probable that a number of them melted and brought water to the Earth.
April 20, 1999Danielle Why is there a bigger temperature change on clear nights then on cloudy night?Clouds act like insulation. After the sun has heated the Earth during the day, the clouds trap the heat near the Earth. On clear nights, the heat is able to dissipate faster.
April 12, 1999Kreg (Canada)Why are deserts so hot during the day and so cold at night?Deserts are very bare. This means that there is nothing to protect it from the sun, so it gets very hot in the day. During the night, there is nothing to hold the warm air near the ground, so the desert cools off very quickly.
March 31, 1999Matt (Alabama, USA)What is the difference between an anticline and a syncline? Also, what is the difference between a plateau and a plain?Anticlines are where layers of stratified rock bend away from each other. Synclines are troughs where the layers dip toward each other from either side. A plain is a large area of flat land. Plateaus are large flat areas which drop off sharply on at least one side.
March 29, 1999Kristy (Missouri, USA)What are the 4 layers of earth called on our planet?The interior layers are the inner core, outer core, mantle, and crust.
February 18, 1999Jason, Ben, and Brodie A long time ago in the age of the dinosaurs, were all the lands interlocking?Yes, during the Mesozoic era. This continent was called Pangaea.
January 8, 1999Mr. RobinsonHow long would it take the Earth to freeze over if it were not for the sun's radiation? And what temperature would it reach (if it didn't reach 0 Kelvin)? Let's say it happened in June and the noonday temperature was 77F when the sunlight stopped - the sun didn't explode just suddenly was not there to give any more heat.It would take about a month for the heat stored in the surface of the Earth to dissipate. Since the interior of the Earth is so hot, and the temperature of the universe so cold (2.7 K), the surface temperature would probably drop to around 200 K and remain there for billions of years, maintained by the energy from the interior of the earth.
November 16, 1998Martin (Texas, USA)What mountain range crosses more lines of latitude than any other?The range which makes up the Rocky Mountains extends from Upper North America to the bottom of South America...although it does not keep the sam name the whole way!
September 3, 1998Rosa (Pennsylvania, USA)What is the Earth made of?This page should do the trick!
August 26, 1998Karl (New Zealand)Why does the earth's core stay hot?When the universe first was formed, the earth was a molten ball. Gradually it has cooled. This formed the crust of the earth, which solidified as the earth cooled. The inside of the earth is still very hot because the earth loses heat very slowly. It will take many years for the core of the earth to cool completely.
June 11, 1998Lew Brian (Phillipines)What is the meaning of tectonic plates?A tectonic plate is one of the pieces that make up the Earth's rigid shell, or lithosphere. The Earth's shell is made up of about nine large pieces (plates) and about a dozen smaller plates. The study of the plates an d how they move is called plate tectonics.

Just a side note...most of the time, we think of plate tectonics being connected with the Earth (because that's where we first noticed it!). But scientists will talk about the possibility of other planets experiencing plate tectonics. They are simply discussing whether that planet's surface moves in a similar way to the surface of the Earth.

May 27, 1998David (Florida, USA) I am told that draining water turns in opposite directions on opposite sides of the equator. If this is true, what is the cause? Do cyclonic storms turn in different directions in different parts of the earth?Yes, this is true. In the Northern Hemisphere, water would swirl counterclockwise; in the Southern Hemisphere, the water would run out clockwise. This is due to the coriolis effect. The coriolis effect is when the Earth's rotation has effect on any moving body of air or water. BUT! For this experiment to work, some extreme measures must be taken. The sink used (or bathtub, etc.) must be symmetrical and of smooth surface. The water must also be left to drain for almost three hours for the Coriolis effect to be seen. You see, forces issued on the water such as those during washing are much stronger than the Coriolis force itself.

Since the coriolis effect affects winds too, cyc lonic storms do turn different directions in the different hemispheres.

May 12, 1998Randy (California, USA) How fast does lava burst out of a volcano?Lava usually flows from volcanos at about 10 km per hour, but it has been known to go as fast as 60 km/hr.
April 13, 1998Martin (Sweden) How can I distinguish between landforms fomrmed by eroisional processes and landforms formed by depositional processes?Erosional landforms usually have steep sides and slice previous layers. For example, the Grand Canyon's sides are composed of many layers of deposited layers, and the river cut through them to form the canyon. Depositional landforms usually are located at the bottom of lakes and oceans. They are generally flat, because they are formed by material washed away by gravity which then settles in flat areas.
April 8, 1998Kevin (Illinois, U.S.A.) Is volcanic ash considered to be a soil sample?Soil is the natural growth medium for land plants. So, since plants grow in volcanic ash, it can be considered a soil.
March 24, 1998Lisa (Michigan, USA) Do mountains have any effect on the rotation of the earth on its axis? As far as 'balancing it out'.Mountains have little or no effect on the rotation of the Earth. Compared to the diameter of the Earth, mountains are no more than a roughness on the surface. If you look at a textured globe, you can see and feel that the mountains are no more than small bumps compared to the Earth.
February 6, 1998Meltem (Istanbul, Turkey)I read from a magazine that mountains can prevent earthquakes. Is this true? What would happen if there were no mountains on earth?As far as I know, mountains cannot prevent earthquakes because earthquakes are generated deep within the Earth. The bottom line is that earthquakes facilite heat escaping from the Earth, so there i s no way that mountains can prevent that process from happening. If there were no mountains, earthquuakes would still happen. Perhaps what the magazine article was trying to say was slightly different that saying that mountains prevent earthquakes.
December 30, 1997Christopher (New Jersey, USA)How did the Appalachian Mountains get round ?The Appalachian Mountains were rounded by the process of erosion. Over time, wind and rain have worn away the sharp points and edges of the mountains. Soon we will have a geology section on the site which will explain more about how that happens.

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