Visualizing Environmental Science

(Marvins-Underground-K-12) #1
Plate Tectonics and the Rock Cycle 301

PROCESS DIAGRAM


Magma Sedimentary
rock

Metamorphic
rock

Cooling and
solidification
Weathering
and erosion,
transport and
deposition,
Heating,pressure, and compaction
and chemical
action

Heating
and melting Heating,
pressure, and
chemical action

Basalt columns are a
type of igneous rock
formed by the cooling
of magma.

Quartzite is a
metamorphic rock
derived from
sandstone.

Sandstone is a type
of sedimentary rock.

Lava is magma that
reaches the surface
through a volcanic vent.

1

2

3

4


Igneous
rock

David Edwards/NG Image Collection

Raul Touzon/NG Image Collection

Taylor S. Kennedy/NG Image Collection

© Phil Degginger / Alamy

Rocks do not remain in their original
form forever. This highly simplified
diagram shows how rock cycles from
one form to another.

/…iÊÀœVŽÊVÞViÊUʈ}ÕÀiÊ£Ó°{
✓✓THE PLANNER

What happens to an
igneous rock as it moves slowly through
the rock cycle?

Think Critically

best prepared of all nations when it comes to earthquake
disasters. Japan lies on a seismically active junction of sev-
eral tectonic plates. (See Chapter 17 for a discussion of
damage to Japan’s nuclear power plants from the quake.)

The Rock Cycle
Rocks, which are aggregates of one or more minerals, fall
into three categories, based on how they formed: igneous,
sedimentary, and metamorphic.
Igneous rocks form when magma
rises from the mantle and cools.
Sedimentary rocks form when
small fragments of weathered,
eroded rocks (or marine organ-
isms) are deposited, compacted, and cemented together.
Metamorphic rocks form when intense heat and pressure
alter igneous, sedimentary, or other meta morphic rocks.

Earth’s internal structure and the basic geologic pro-
cesses that we have presented in this chapter result in a
rock cycle, in which rock moves from one physi cal state or
location to another (ˆ}ÕÀiÊ£Ó°{). The rock cycle is similar
to the other cycles of matter, such as the carbon and hydro-
logic cycles (see Chapter 5). However, rocks are formed
and move through the environment over geologic time,
much more slowly than the elements of the other cycles.


  1. What are tectonic plates and plate boundaries?
    Where do earthquakes and volcanoes usually
    occur? Why?

  2. What are the three types of rock? How are the
    three types of rock interconnected in the rock
    cycle?


minerals Elements
or compounds of
elements that occur
naturally in Earth’s
crust.
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