Hampden-Wilbraham Regional District

TASA: The Wonders of Rocks and Minerals
The Rock Cycle Script

 The rock cycle is one way of seeing how all rocks are interrelated. Note: Through out this section you can review the rock cycle by clicking on the small icon in the upper right corner.

The rock cycle shows how the the basic rock types form….

…and illustrates how geologic processes change one rock type into another.

Igneous rocks form when molten (melted) material called magma cools and solidifies.

This process, called crystallization, may occur either at the Earth’s surface… (Basalt) (Click replay to review crystallization.)

… or beneath the Earth’s surface. (Granite) (Click replay to review crystallization.)

When igneous rocks are exposed at the surface, they will undergo weathering, a process which slowly breaks up rock. (Click replay to review weathering by freezing, thawing, refreezing and rethawing.)

The rock fragments are picked up and carried away by running water…

…glaciers…

… wind ...

 …or waves, while breaking the fragments into smaller and smaller pieces.

Eventually these particles and dissolved materials, called sediment, are deposited.

Next, these sediments are converted to rock, either by compaction….(Click replay to review compaction.)

… or by cementation as percolating water coats the sediment with mineral matter, and gradually cements the particles together. (Click replay to review cementation.)

The result is sedimentary rocks such as shale, sandstone, and conglomerate.

If sedimentary rock is buried deep within the Earth, it will be subjected to great pressures and heat. (Click replay to review result of pressure on sedimentary rock..)

Rocks subjected to great pressures and high temperatures change to metamorphic rocks. (Click replay to review formation of metamorphic rock.)

When metamorphic rock is subjected to still greater heat and/or pressure changes, it may melt to create magma. (Click replay to magma formed from metamorphic rock.)

When magma cools and solidifies, it forms igneous rock.

As we have seen, rocks are transformed from one type to another in an unending cycle we call the rock cycle.

Although rocks may seen to be unchanging masses….

…the rock cycle shows they are not. The changes, however, take time-great amounts of time.

Which of the following is not a major class of rocks? Choose: sedimentary, igneous, plutonic or metamorphic.

___________ rocks form from cooling magma. Choose: sedimentary, igneous or metamorphic

The gradual breakup of rock at the Earth’s surface is called _________ .
Choose crystallization, weathering, magma, or thawing.

Where are metamorphic rocks normally formed? Choose: on the surface of the Earth, under water, within the Earth or everywhere

These events can generate a frothy mass of glass fibers called pumice, which sometimes floats in water. Click replay to see float.