Earth Science Lab Start with a rock, or with magma, and change its conditions. Melt it, cool it, weather it, bury it or squeeze it, and see which real rock it becomes and where inside Earth each change happens.
New here? Granite formed deep underground. Press a process to change it: try Uplift and exposure, then Weathering and erosion. Dashed options can’t happen yet; press one to find out why.
Depths follow the scale on the left. Mountains and the volcano are drawn much taller than they really are.
Magma cools and hardens into igneous rock.
Mountain building lifts buried rock; erosion uncovers it.
Rain, ice and wind break rock down and carry it away.
Loose grains settle in layers where water or wind slows.
Buried layers are squeezed and glued into rock.
Carried deep, rock gets hot enough to melt into magma.
Igneous, intrusive
Coarse-grained: big interlocking crystals you can see.
Where it formed: cooling and crystallizing, slowly underground
Solid arrows: the loop in most textbooks. Dashed arrows: shortcuts. Orange arrows: your journey, with how many times you took each.
Earth doesn’t make new rock from nothing. It recycles the rock it has, very slowly. There are three families of rock, named for how they form:
Any rock can become any other kind, if conditions change. A granite can be uplifted, weathered into sand and mud, cemented into shale, squeezed into slate, and melted into magma again. That journey can take hundreds of millions of years.
Two energy sources keep rock moving. The Sun heats the air and water, which drives weather and the water cycle: rain, ice and wind break rock apart, and gravity carries the pieces downhill. Earth’s internal heat melts rock, bakes and squeezes it deep underground, and moves the plates that push rock down and lift mountains up.
Textbook diagrams often show a neat circle: igneous to sedimentary to metamorphic and back. Real rocks take shortcuts. Granite can be squeezed straight into gneiss. Sandstone can be lifted up and weathered into new sand. Basalt can melt again without ever becoming sediment. The builder’s rock cycle diagram draws every shortcut you take.
Every rock in the builder, with a drawing of its texture. Texture is the best clue to how a rock formed: crystal size tells you how fast it cooled, rounded grains tell you water carried them, and lined-up minerals tell you it was squeezed.
Magma that cools slowly, deep underground, has time to grow big crystals you can see. These rocks reach the surface only after uplift and erosion uncover them.
Coarse-grained: big interlocking crystals you can see.
Silica-rich magma cools slowly, deep underground. Slow cooling gives crystals thousands of years to grow large.
Kitchen countertops, and Mount Rushmore, which is carved in granite.
Coarse-grained: black and white crystals, like salt and pepper.
Andesitic magma cools slowly, deep underground, and grows large crystals.
Black-and-white speckled stone sold as “granite” for countertops is often diorite.
Coarse-grained: dark crystals you can see.
Basaltic magma cools slowly underground. The lower part of the ocean crust is gabbro.
Dark stone sold as “black granite” for countertops and gravestones.
Lava cools fast, so its crystals stay tiny, or there are none at all. Gas bubbles can leave holes.
Fine-grained: crystals too small to see, often with flow bands.
Silica-rich lava cools quickly at the surface, so its crystals stay tiny. It has the same minerals as granite.
The pink and pale lava flows and canyon walls of Yellowstone National Park.
Fine-grained gray rock, often with a few larger crystals.
Andesitic lava cools quickly at the surface. A few crystals that grew in the magma chamber stand out in it.
Named after the Andes Mountains, whose volcanoes erupt it.
Fine-grained: dark, with crystals too small to see.
Runny basaltic lava cools quickly at the surface. It is the most common volcanic rock on Earth, because the ocean crust is made of it.
Hawaii’s lava flows, the columns of the Giant’s Causeway, and the dark patches on the Moon.
Glassy: smooth and shiny, with no crystals at all.
Thick, silica-rich lava cools before crystals can grow, so it sets as natural glass.
Ancient people chipped it into razor-sharp arrowheads and blades.
Vesicular: pale and frothy, full of tiny gas holes.
In an explosive eruption, gas froths sticky lava like a shaken soda. It cools in seconds into a glassy foam.
Light enough to float on water; used in pumice stones and to make “stonewashed” jeans.
Vesicular: dark red or black, with many large gas holes.
Gas-rich basaltic lava is thrown out of a vent in fountains and cools full of bubbles.
The red or black “lava rock” in gardens and gas grills; cinder cones like Sunset Crater in Arizona.
Pieces of older rock, and shells, settle in layers. Buried and squeezed, the layers are glued into rock. Many sedimentary rocks hold fossils.
Rounded pebbles cemented together, like natural concrete.
Layers of river gravel are buried, squeezed and glued together by minerals left by water.
The tilted red rock layers of Red Rocks Amphitheatre near Denver.
Sand-sized grains cemented together; feels gritty.
Layers of sand are buried, squeezed and cemented. Slanting lines inside it can show where old dunes or ripples were.
The red cliffs of Zion and Arches National Parks, and many old buildings.
Very fine grains in thin layers; splits into flakes.
Layers of mud are buried and squeezed until the water is pressed out. It is the most common sedimentary rock.
Ground up to make bricks; the Burgess Shale in Canada holds famous fossils.
Pale rock of calcite, often with fossil shells.
Layers of shells, coral and lime mud are buried and cemented.
Used to make cement; the White Cliffs of Dover are chalk, a kind of limestone.
Heat and pressure change a rock’s minerals and texture while it stays solid. Squeezing from one direction lines minerals up into layers or bands (foliation).
Foliated: dull and smooth; splits into flat sheets.
Shale is squeezed and warmed. Its tiny flat minerals line up, so it splits cleanly along one direction.
Roof tiles, old school chalkboards and the beds of pool tables.
Foliated: shiny, silky and often wavy.
Slate is heated a little more. Its mica crystals grow just big enough to give it a silky shine.
Found in old mountain belts such as the Appalachians.
Foliated: sparkly flakes of mica you can see, sometimes with garnets.
Hotter still, the mica grows into flakes you can see, and new minerals such as garnet can form.
Manhattan Schist is the bedrock that holds up New York City’s skyscrapers.
Banded: light and dark stripes of minerals.
At high grade, minerals separate into light and dark bands. Shale, schist or granite can all become gneiss.
Some of Earth’s oldest known rocks, the Acasta Gneiss in Canada, are about 4 billion years old.
Non-foliated: interlocking calcite crystals, often white.
Heat and pressure make the calcite in limestone grow into larger crystals that lock together. Fossils disappear.
Michelangelo’s statue David and the Taj Mahal are made of marble.
Non-foliated: quartz grains fused together; very hard.
Heat and pressure fuse the quartz grains of sandstone. It breaks across the grains, not around them.
Hard stone for countertops and the gravel under railroad tracks.
Foliated: green and flaky.
Basalt, gabbro or andesite is squeezed and warmed with water. Green minerals such as chlorite grow and line up.
Found in “greenstone belts”, some of the oldest rocks on Earth.
Dark and heavy, with lined-up black crystals.
Basalt, gabbro or andesite is heated to medium or high grade. Long black hornblende crystals grow, often lined up.
Polished as dark building stone and countertops.
Every process needs its own conditions. Weathering happens only at the surface, where rain, ice and wind can reach the rock. Metamorphism and melting happen deep underground, where it is hot and the rock above presses down hard. All of these values are rough ranges.
| Process | Where | Depth | Temperature | Pressure | Time | Energy |
|---|---|---|---|---|---|---|
| Cooling slowly, underground | Underground, in a chamber of magma | About 2–14 km down | About 650–1,200 °C magma, depending on its make-up | About 520–3,700 times the air pressure at sea level | Thousands to millions of years, so big crystals have time to grow | Heat flows out of the magma into the cooler rock around it |
| Cooling quickly, as lava | At the surface, as a lava flow | At the surface | Lava at about 650–1,200 °C cools to air temperature | Air pressure at the surface | Hours to a few years: too fast for big crystals | Heat escapes from the lava into the air, water and ground |
| Uplift and exposure | Brought up to the surface, as mountains rise and erosion strips away the rock above | At the surface | Cools as it rises, ending at surface temperatures | Air pressure at the surface | About 8 million years to rise 8 km at 1 mm per year | Earth’s internal heat drives the plate motions that build mountains; erosion, driven by the Sun, uncovers the rock |
| Weathering and erosion | At the surface | At the surface | Surface temperatures, like the weather | Air pressure at the surface | Years to millions of years | Sunlight drives the weather and the water cycle; gravity pulls water, ice and grains downhill |
| Deposition | Rivers, beaches, lakes and the sea floor | At the surface | Surface temperatures, like the weather | Air pressure at the surface | Years to thousands of years for each layer | Gravity: grains settle when the water or wind carrying them slows down |
| Compaction and cementation | Buried under younger layers | About 1–5 km down | About 25–125 °C | About 260–1,300 times the air pressure at sea level | Thousands to millions of years | Gravity: the weight of the layers above squeezes the grains, and minerals in the water glue them |
| Heat and pressure, very low grade | Deep under a mountain range | About 8–12 km down | About 200–300 °C (very low grade) | About 2,100–3,100 times the air pressure at sea level | Millions of years | Earth’s internal heat, plus squeezing as plates push together |
| Heat and pressure, low grade | Deep under a mountain range | About 12–16 km down | About 300–400 °C (low grade) | About 3,100–4,200 times the air pressure at sea level | Millions of years | Earth’s internal heat, plus squeezing as plates push together |
| Heat and pressure, medium grade | Deep under a mountain range | About 16–24 km down | About 400–600 °C (medium grade) | About 4,200–6,300 times the air pressure at sea level | Millions of years | Earth’s internal heat, plus squeezing as plates push together |
| Heat and pressure, high grade | Deep under a mountain range | About 24–32 km down | About 600–800 °C (high grade) | About 6,300–8,400 times the air pressure at sea level | Millions of years | Earth’s internal heat, plus squeezing as plates push together |
| Melting silica-rich (felsic) rock | Deep in the crust | About 26–32 km down | About 650–800 °C for silica-rich (felsic) rock | About 6,800–8,400 times the air pressure at sea level | Thousands to millions of years | Earth’s internal heat |
| Melting medium silica (intermediate) rock | Near the bottom of the crust | About 32–40 km down | About 800–1,000 °C for medium silica (intermediate) rock | About 8,400–10,000 times the air pressure at sea level | Thousands to millions of years | Earth’s internal heat |
| Melting silica-poor (mafic) rock | In the upper mantle, below the crust | About 40–48 km down | About 1,000–1,200 °C for silica-poor (mafic) rock | About 10,000–13,000 times the air pressure at sea level | Thousands to millions of years | Earth’s internal heat |
Depths for heat and pressure and for melting assume the crust gets about 25 °C hotter for every kilometer down. Real places can be much hotter or cooler, for example near magma or where a cold plate sinks.
Gneiss is a high-grade metamorphic rock. It forms at about 600–800 °C. How deep is that, how hard is the rock squeezed, and how long does it take to come back up?
How deep? In much of the crust the temperature rises about 25 °C for every kilometer down. To reach 700 °C:
depth = 700 °C ÷ 25 °C per km = 28 km
How squeezed? Each kilometer of rock above presses down with about 260 times the air pressure at sea level. So 28 km of rock presses with about 28 × 260 ≈ 7,300 times the air pressure we feel.
How long to come back up? Mountains rise, and erosion wears the rock above away, at roughly 1 mm per year. One millimeter a year for a million years is 1,000,000 mm, which is 1 km. So:
time = 28 km ÷ 1 km per million years = 28 million years
In a human lifetime of about 80 years, the gneiss would rise only 8 cm. That is why gneiss reaches the surface only where mountains have been rising and wearing away for tens of millions of years.
Try it in the builder: start from shale, choose Heat and pressure, high grade, then Uplift and exposure, and read the depth and time in the Conditions panel.
Real rocks don’t come in neat boxes. Each name in the builder stands for a range of rocks that blend into each other, and many real rocks are left out, such as hornfels (rock baked by nearby magma), migmatite, metaconglomerate, dacite, coal and rock salt. Conditions in Earth change smoothly, but the builder turns them into steps with rough ranges: the grades of heat and pressure, the melting temperatures, and depths worked out from a steady rise of about 25 °C per kilometer, when real places can be much hotter or cooler. Each click stands for thousands to millions of years, and uplift always uses 1 mm per year.
The model tracks only what a rock is roughly made of. It treats melting as if the whole rock melts into magma of the same make-up, but real rocks usually melt only partly, and the first melt is richer in silica; magmas also mix and change. Any sediment can settle in any of the four places, even though real sediment is a mix from many rocks. In the real Earth, fresh basaltic magma keeps rising from the mantle and adds new material to the cycle; in the builder, you can start from it. The cross-section is a diagram, not a real place: depths follow the scale, but mountains and the volcano are drawn many times too tall.
A one-page printable worksheet for grades 6–10, about 15 minutes: students follow a granite through six processes in the builder, record each rock, where it forms and how hot it gets, and answer six questions about energy, depth and shortcuts.
Share the builder with your class in one click. Students need no accounts or logins.
Share to Google ClassroomThe rock cycle is the slow recycling of Earth’s rock. Rock melts into magma, which cools into igneous rock. Weathering breaks rock into sediment, which is buried and cemented into sedimentary rock. Heat and pressure change rock into metamorphic rock. Any rock can be changed again, so the same material is used over and over, across millions of years.
Igneous rock forms when magma or lava cools, like granite and basalt. Sedimentary rock forms from layers of sediment or shells that are buried and cemented, like sandstone and limestone. Metamorphic rock forms when heat and pressure change a rock without melting it, like slate and marble.
Two sources of energy. Energy from the Sun drives the weather and the water cycle, so rain, ice and wind break rock down and move it; gravity pulls the pieces downhill. Earth’s internal heat melts rock, drives metamorphism, and moves the plates that build mountains and carry rock deep underground.
Usually millions of years. Weathering can take thousands of years, a buried rock may take millions of years to change, and uplift is slow: at about 1 mm per year, a rock 28 km down needs about 28 million years to reach the surface. Some steps are fast, though: lava can cool into rock in hours.
No. There is no fixed loop. Igneous rock can be squeezed straight into metamorphic rock or melted again; sedimentary rock can be uplifted and weathered into new sediment; metamorphic rock can be weathered, changed again or melted. Try it in the builder: the rock cycle diagram counts every shortcut you take.
They are the same molten rock. It is called magma while it is underground and lava once it erupts at the surface. Magma that cools underground makes coarse-grained rocks like granite; lava cools fast and makes fine-grained or glassy rocks like basalt and obsidian.
Yes. It is free with no sign-up and runs on school Chromebooks. Use the printable activity to follow a rock through six processes, then let students try Challenge mode: two build-a-rock puzzles and six questions about textures, foliation and energy. Teachers can find the answer key on the For teachers page.