The Earth’s rocky outerlayer (the lithosphere) is broken up into around seventeen major pieces that we call tectonic plates.   These plates form a jigsaw pattern around the planet with their edges interacting to cause earthquakes, volcanoes, mountain ranges and deep ocean trenches.    But what makes up these jigsaw pieces?


The crustal plates are made up of the two types of crust – continental crust and oceanic crust with a small section of the underlying mantle.   This solid material is called the lithosphere.  We classify plates into three groups depending on their size – Major, Minor, and Micro plates.

Major Plates

These are plates that are greater than 20 million square kilometers.

  • Pacific Plate – 103,300,000 km2
  • North American Plate – 75,900,000 km2
  • Eurasian Plate – 67,800,000 km2
  • African Plate – 61,300,000 km2
  • Antarctic Plate – 60,900,000 km2
  • Indo-Australian Plate – 58,900,000 km2
  • South American Plate – 43,600,000 km2

By the way, lots of maps divide the Indo-Australian plate into two separate plates…but I have not seen any evidence that they are separate.   One day we will have evidence for one way or the other…but for now, the evidence does not show them being two plates.

Minor Plates

These are plates that are less than20 million square kilometers but greater than one million square kilometers.

  • Somali Plate – 16,700,000 km2
  • Nazca Plate – 15,600,000 km2
  • Philippine Sea Plate – 5,500,000 km2
  • Arabian Plate – 5,000,000 km2
  • Caribbean Plate – 3,300,000 km2
  • Cocos Plate – 2,900,000 km2
  • Caroline Plate – 1,700,000 km2
  • Scotia Plate – 1,600,000 km2
  • Burma Plate – 1,100,000 km2
  • New Hebrides Plate – 1,100,000 km2

Micro Plates

These are plates that are less than one million square kilometer in size.  Currently, around 56 have been identified, but this changes as new information is discussed by scientists studying the Earth’s plates.

crustal plates
Imagine a hard boiled egg with the shell cracked before you peel it.   You will find large pieces, smaller pieces and in some places lots of tiny pieces.  That is what the Earth’s crustal plates are like.

One major misconception is that a plate can only have ONE type of crust.  For example, a plate made up of just continental crust.    But this is not the case.  Most plates are made up of a combination of crustal types with oceanic crust welded onto continental crust.   So the boundaries between the types of crust are NOT necessarily the boundaries between plates.

Also, you have to remember that sea level does not govern where continental crust ends.  Continental crust can extend way out under the ocean.

One important difference between these two types of crust is their “buoyancy” dues to the density of the rocks. Because continental crust is made up of rocks of all types, including those rich in quartz, they are relatively less dense than the oceanic crust which is made up of silica-poor (ie no free quartz) basalt.   Becuase of the ‘buoyancy of continental crust, it has a survived many of the changes on the surface of our planet, and so here you find the very oldest rocks of the crust.

So now we have the jigsaw pieces.   Next, we need to think about how those pieces interact with each other.  But that’s another story….

For more of our blogs on Plate Tectonics see these posts:

What is the Lithosphere?

Traditionally, when we talk about the layers of our planet we talk about the inner core, outer core, mantle, and ...
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Introduction to Plate tectonics

Learn the basics of the theory of Plate Tectonics in less than 10 minutes!   Why do earthquakes and volcanoes ...
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Lava in Lihue – Role play activity

Description : A classroom role-play activity where students play the role of various town people when their town is being ...
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Rocks of Ages

Description : Student activity where they calculate the speed of a moving tectonic plate by using the ages of rocks ...
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Understanding Polar Reversals

Understanding polar reversals helps us to understand an important piece of evidence for Plate Tectonics. When molten rock cools, some ...
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Divergent Plate Boundaries

One of the most amazing places on the Earth's is where two massive tectonic plates are moving apart.  Almost 99% ...
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Evidence for Plate Tectonics

The evidence for Plate Tectonics is very conclusive.  It is a very well supported theory, and while scientific debate continues ...
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Boundaries – how the plates interact

The Earth's plates don't just sit there.  They move and interact at their boundaries - and that is what makes ...
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Plates – understanding the tectonic jigsaw pieces.

The Earth's rocky outerlayer (the lithosphere) is broken up into around seventeen major pieces that we call tectonic plates.   ...
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The Earth’s Crust – a simple way to view it.

The Earth's crust - that outermost rocky layer of our planet - can be daunting to understand.   To start ...
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Plates – understanding the tectonic jigsaw pieces.

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