s

Question 1

geologic time scale

Question 2

weathering

Answer 2

. Weathering is
the process by which rock materials are broken down by the action of physical and
chemical processes.

Question 3

sediment

Answer 3

Fragments of weathered rock,
called sediment, are an important part of soil

Question 4

physical weathering

Answer 4

Physical weathering is the mechanical breakdown of rocks into smaller pieces. Physical
weathering involves only physical changes.

Answer 5

. Erosion is the process by which wind, water, ice, or
gravity transport weathered materials from one location to another

Question 6

chemical weathering

Answer 6

Chemical weathering is the breakdown and decomposition of rocks as a result of
chemical reactions and processes. Unlike physical weathering, chemical weathering
changes the composition of rocks through a chemical process. It weakens or dissolves
rock over time. Agents of chemical weathering include air, water, and plants.

Answer 7

Deposition occurs
when the eroded materials are dropped, or laid down.

Answer 8

Acid precipitation is rain or other
precipitation that is more acidic than
normal. Acid precipitation reacts with
certain types of rocks, weakening them
and making them more susceptible to
physical weathering

Answer 9

Iron-containing rocks can react with
oxygen and water in a process called
oxidation. Oxidation can give the
rocks a reddish color, similar to rust. In
fact, the same process causes rust to
form on bicycles left out in the

Answer 10

Plants such as lichens and mosses
produce weak acids. When the
plants grow on rocks, the acids
slowly, but steadily, wear down
the rocks.

Answer 11

A mineral is a naturally occurring and usually inorganic solid. It has a definite chemical
composition and an orderly internal structure. A mineral’s properties depend on the
kinds of atoms or molecules that make up the mineral.

Answer 12

Cooling magma below ground and cooling lava
above ground both form igneous rocks.

Answer 13

When sediments are compacted or are cemented together by new
minerals, sedimentary rock forms.

Answer 14

The processes on Earth that form rock take such a long time that it is hard to
imagine that they happen continuously. All rock that is on and inside Earth was
magma at some point in the past.

Answer 15

lava
above ground both form igneous rocks

Answer 16

. Magma
cools below ground

Answer 17

When large changes of temperature, pressure,
or both cause the texture and mineral content
of existing rock to change over millions of years,
metamorphic rock forms