Rootless cone

High school (ages 12+)
Environment & Earth

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/rootless-cone

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the formation mechanism?Phreatic or phreatomagmatic explosions driven by steam expansion
2. What is the subsurface heat source?Interaction of groundwater with shallow magma or hot rocks
3. How do rootless cones form?When underground water gets hot enough, it turns into steam. The steam expands quickly, pushes out the soil and rocks, and builds a cone around the vent.
4. Why don't rootless cones have roots?Rootless cones aren't connected to magma below the ground. They are made only by the steam that comes from hot water, so they don't need a magma "root" to form.

Phreatic Explosion: An explosive eruption caused by the rapid heating and expansion of groundwater.
Phreatomagmatic: An eruption involving the interaction of magma and water.
Lithology: The physical characteristics of a rock, such as its color, texture, and grain size.
Geothermal Gradient: The rate at which temperature increases with depth within the Earth.