<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation
You are viewing an older version of this Concept. Go to the latest version.

Igneous Rock Classification

Igneous rocks are grouped based on silica content and whether the rock is extrusive or intrusive.

Atoms Practice
Practice Igneous Rock Classification
Practice Now
Rock Stars

Rock Stars


License: CC BY-NC 3.0

All rocks have an interesting geological history. Only a few rocks are important in human history. People have been kissing the Blarney Stone for centuries.

Famous Rocks

  • Plymouth Rock was a traveler, like the Pilgrims. It is a glacial erratic.
  • Some sources say that the Blarney Stone is a bluestone, but that’s not a rock type. The British call a rock of any origin that has been brought in from elsewhere a bluestone.
  • Ayer’s Rock rises above the flat Australian Outback. The rock is a sacred site to the native people. Ayer’s Rock is a World Heritage Site.

Explore More/Show What You Know/Can You Apply It?

With the links below, learn more about a few famous rocks. Then answer the following questions.

  1. What type of rock is Plymouth Rock? How do rocks of that type form?
  2. What is the geologic history of Plymouth Rock? Why does the rock break fairly easily?
  3. What type of rock is the Blarney Stone? Which of the major rock types is that?
  4. What is the legend of the Blarney Stone?
  5. Why is Ayer’s Rock famous? What’s the geological history of the rock?

Image Attributions

  1. [1]^ License: CC BY-NC 3.0


Please wait...
Please wait...

Original text