lesson 22: the rock cycle

Question 1

information about the rock cycle

Answer 1

A useful way to illustrate how the three main types of rock are related to one another and how changes to rocks happen in a recurring sequence is the rock cycle. It can be presented in a diagram like the one below. The concept of the rock cycle is attributed to James Hutton (1726–1797), the 18th-century founder of modern geology. The main idea is that rocks are continually changing from one type to another and back again, as forces inside the earth bring them closer to the surface (where they are weathered, eroded, and compacted) and forces on the earth sink them back down (where they are heated, pressed, and melted). So the elements that make up rocks are never created or destroyed — instead, they are constantly being recycled. The rock cycle helps us to see that the earth is like a giant rock recycling machine!

Question 2

metamorphic rock + melting =

Answer 2

magma

Question 3

magma + cooling

Answer 3

igneous rock

Question 4

igneous rock + melting =

Answer 4

magma

Question 5

igneous + heat and pressure =

Answer 5

metamorphic

Question 6

igneous +weathering and erosion =

Answer 6

sediment

Question 7

metamorphic + weathering and erosion

Answer 7

sediment

Question 8

sedimentary + weathering and erosion =

Answer 8

sediment

Question 9

sedimentary + weathering and erosion =

Answer 9

sediment

Question 10

sediment + compacting and cementing =

Answer 10

sedimentary

Question 11

sedimentary +heat and pressure

Answer 11

metamorphic

Question 12

woah! you know so much about the rock cycle

Answer 12

Rocks get moved around as a result of plate tectonics and erosion. Even when the
rocks stay in one place; they may be subjected to changes in heat and/or pressure.
Furthermore, rocks that form in a particular environment (say deep within Earth) are
naturally unstable when they are become exposed to the conditions in a drastically
different environment (say at Earth’s surface). The result? Rocks sometime change
from one type of rock to another; for example from igneous to sedimentary to
metamorphic to igneous to metamorphic…. The rocks get recycled, so to speak. The
scientific term for this process is the rock cycle It is not so much that individual rocks change (poof!) as that vast areas of rocks may be
slowly transformed. The atoms that make up the rocks get used again and again.
Nothing is lost, except some heat from inside Earth which radiates away from Earth into
space.

Question 13

sedimentary rock could:

Answer 13

• Breakdown be transported and redeposited, then be formed into sedimentary rock again.
• Be exposed to heat and pressure underground and change into metamorphic rock.
• Melt underground and become magma, then cool to form an igneous rock.

Question 14

igneous rock could

Answer 14

• Remelt underground to form magma, then become igneous rock once more.
• Weather, erode, be deposited, and buried; become compacted and cemented to form sedimentary rock.
• Be exposed to heat and pressure underground and change into metamorphic rock.

Question 15

metamorphic rock could

Answer 15

• Be altered a second time by heat and pressure and become a different type of metamorphic rock.
• Weather and erode on Earth’s surface; then, as sediments, go through the processes of becoming sedimentary rock.
• Melt deep underground from extreme heat and pressure, become magma, and cool to form igneous rock.