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Liquid Rock

Short answer: Lava is molten rock erupted at the surface; underground, the same material is called magma.

Most magma forms in the upper mantle, and a key way rock melts there is decompression: as hot mantle rises, the pressure on it drops and it partly melts, which is why mid-ocean ridges and hotspots such as Iceland and Hawaii are so volcanic. Erupted lava typically ranges from about 700 to 1,200 °C (1,300 to 2,200 °F). Runny basaltic lava can travel quickly, while silica-rich lava is thick and slow. As it cools, lava can crack into hexagonal basalt columns or build up islands. The footage is drone video of lava fountaining and flowing in Iceland.

VideoWrite-up1 sources
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What should you know about Liquid Rock?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Lava typically ranges from 700 to 1,200 °C.

    DD-298-F01 · Write-up · Exhibit C (Temperature)

  2. Rising mantle rock melts as pressure drops.

    DD-298-F02 · Write-up · Exhibit B (Decompression melting)

Video transcript: Liquid Rock: Lava Can Flow at 1,200 °C

DID YOU KNOW? Lava is molten rock expelled by a volcano during an eruption. It originates from the Earth's mantle where intense heat and pressure cause rock to melt. When lava reaches the surface it can flow at varying speeds depending on its composition and temperature. The temperature of lava typically ranges between 700 to 1,200 degrees Celsius or 1,300 to 2,200 degrees Fahrenheit. The flow and cooling of lava can create various geological formations such as basalt columns and volcanic islands. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 27.0s Reel ·

Video coming soonLiquid Rock · Instagram Reel
Liquid Rock: Lava Can Flow at 1,200 °C Instagram Reel · · 27.0s

The write-up

Lava can flow at 1,200 °C. Most mantle melting happens when pressure drops, not when it rises.

  1. Exhibit A

    Magma at the surface

    Lava is molten rock erupted at the surface.

  2. Exhibit B

    Decompression melting

    Rising mantle rock partly melts as pressure drops.

  3. Exhibit C

    Temperature

    Lava typically ranges from about 700 to 1,200 °C.

  4. Exhibit D

    Runny or thick

    Basaltic lava flows easily; silica-rich lava is thick and slow.

  5. Exhibit E

    Cooling shapes

    Cooling lava can form basalt columns and islands.

Questions people ask about Liquid Rock

What's lava called underground?

It becomes lava when it erupts.

Source: Write-up · Exhibit A (Magma at the surface) · Wikipedia: Lava

What triggers decompression melting?

Rising mantle rock partly melts.

Source: Write-up · Exhibit B (Decompression melting) · Wikipedia: Lava

What's lava's typical temperature range?

That's 1,300 to 2,200 °F.

Source: Write-up · Exhibit C (Temperature) · Wikipedia: Lava

Which lava flows most easily?

It has less silica.

Source: Write-up · Exhibit D (Runny or thick) · Wikipedia: Lava

What can cooling lava form?

It cracks into columns.

Source: Write-up · Exhibit E (Cooling shapes) · Wikipedia: Lava

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What's lava called underground?

    1. Magma
    2. Basalt
    3. Obsidian
    4. Corium
    Show the answer

    Answer: A. Magma It becomes lava when it erupts. Source: Write-up · Exhibit A (Magma at the surface) · Wikipedia: Lava

  2. What triggers decompression melting?

    1. A drop in pressure
    2. A rise in pressure
    3. Cold water
    4. Sunlight
    Show the answer

    Answer: A. A drop in pressure Rising mantle rock partly melts. Source: Write-up · Exhibit B (Decompression melting) · Wikipedia: Lava

  3. What's lava's typical temperature range?

    1. 700 to 1,200 °C
    2. 100 to 200 °C
    3. 3,000 to 5,000 °C
    4. 50 to 80 °C
    Show the answer

    Answer: A. 700 to 1,200 °C That's 1,300 to 2,200 °F. Source: Write-up · Exhibit C (Temperature) · Wikipedia: Lava

  4. Which lava flows most easily?

    1. Basaltic
    2. Silica-rich
    3. Frozen
    4. Granitic
    Show the answer

    Answer: A. Basaltic It has less silica. Source: Write-up · Exhibit D (Runny or thick) · Wikipedia: Lava

  5. What can cooling lava form?

    1. Basalt columns
    2. Coral reefs
    3. Limestone caves
    4. Glaciers
    Show the answer

    Answer: A. Basalt columns It cracks into columns. Source: Write-up · Exhibit E (Cooling shapes) · Wikipedia: Lava

Cite this case file

Easterling, Marcus. "Liquid Rock." The Detail Department (DetailEnjoyer), case file DD-298, last updated Aug 14, 2024. https://detailenjoyer.com/case/liquid-rock/

Permalink: https://detailenjoyer.com/case/liquid-rock/ · Last updated

Markdown version

Cite a single fact by its ID, for example DD-298-F01 → https://detailenjoyer.com/case/liquid-rock/#DD-298-F01