Marble Deformation

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En provenance du cours de American Museum of Natural History

The Dynamic Earth: A Course for Educators

95 notes

American Museum of Natural History

The Dynamic Earth: A Course for Educators

95 notes

The AMNH course The Dynamic Earth: A Course for Educators provides students with an overview of the origin and evolution of the Earth. Informed by the recently released Next Generation Science Standards, this course examines geological time scales, radiometric dating, and how scientists “read the rocks.” We will explore dramatic changes in the Earth over the last 4 billion years, including how the evolution of life on Earth has affected its atmosphere. In addition to looking at geology on a global scale, participants will take to their own backyards to explore and share their local geologic history. Course participants will bring their understanding of the dynamic Earth - along with content resources, discussion questions, and assignments - into their own teaching.

À partir de la leçon

Plate Tectonics: Mountain Building

You will learn how convection causes solid rock to flow in the Earth’s mantle and how the movement of the Earth’s tectonic plates forms mountains. You will also learn how to identify and address common student misconceptions about plate tectonics.

The Structure of Mountain Belts: The Swiss Alps12:29

Ductility of Rocks1:16

Marble Deformation2:35

Scientists at Work: Mountain Building5:38

Rencontrer les enseignants

Edmond Mathez, Ph.D.
Curator and Professor
Department of Earth and Planetary Sciences
Ro Kinzler, Ph.D.
Senior Director
Science Education

I'm in the Hall Planet Earth, and I'm standing in front

of a series of marble cylinders that illustrate how rocks deform.

This is Carrera marble, the same white marble that Michelangelo

used to create David, and it's still being mined in Italy.

And all of these cylinders.

started out just like this one, to which nothing has happened.

But in these other cylinders,

we compressed them at, under different conditions to illustrate how rocks deform.

An important property of rocks is

that they their, their deformation is different.

The manner in which they deform.

is different, depending on the conditions of deformation.

In our everyday experience, we realize that rocks can

break, they behave brittlely, but there are other conditions

in which rocks actually flow, like putty,

like plastic, and that transition from brittle.

To what's known as ductile deformation are illustrated by these cylinders.

So, all of these cylinders began life like this

cylinder on the left and nothing has happened to this.

But all of these other cylinders. Were deformed under

a compressive stress at 400 degrees centigrade, so in other words,

very high temperature, and at progressively higher confining pressures.

These particular cylinders you can clearly see

fractured, and in fact, so did these two,

but the fractures in these two cylinders are

much smaller and they're more difficult to see.

In contrast,

these cylinders did not fracture yet you can see they're both shorter.

These cylinders experience what's known as ductile deformation.

The deformation is accomplished by the change in the

shapes of the grains that actually make up these cylinders.

So this is a microscopic process.

This is a macroscopic. Process.

This illustrates the very important property again

that rocks flow.

That's a very, very important property because it

really determines the nature of the planet for example.

The mantle of the Earth is largely solid, but it flows.

It's the reason that we have plate tectonics.

So it's a consequence of the fact that rocks

can behave ductily under conditions of high temperature and pressure.

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