Study Guide Notes: Chapter 4 Unit Test
OVERVIEW:
Lesson 1: Rocks and the Rock Cycle (begins on p. 110)
Geologists use texture and the composition of grains to classify types of rocks.
Vocabulary:
Rock – is a natural, solid mixture of minerals or grains.
Grain – the fragments that make up rock.
Texture – describes the size & arrangement of minerals or grains in a rock.
Rock Types: (Igneous, Sedimentary, Metamorphic)
Igneous Rocks – are rocks that form from cooling and crystalizing magma and lava.
Magma – is molten or liquid underground rock.
Lava – is molten rock that erupts onto Earth’s surface.
Extrusive Rocks – are rocks formed on the surface of the Earth when volcanic material erupts, cools, and
crystallizes. *(creating fine-grain texture)
Intrusive Rocks – are rocks formed underground as magma slowly cools. *(creating large crystals)
Sedimentary Rocks – are rocks formed from rock fragments and materials that include mineral crystals,
or the remains of certain plants and animals.
Compaction – occurs when the weight of layers of sediment forces out fluids and decreases the space
between the grains of rocks.
Cementation – occurs when minerals dissolved in water crystallize between sediment grains of rocks.
Clastic – are types of Sedimentary rocks that made up of broken pieces of minerals and rock fragments. The
broken pieces and fragments are called clasts.
Conglomerate – rounded clasts that are formed by fast moving water.
Breccia – are angular fragments that form clastic sedimentary rocks.
Chemical – are rocks formed when minerals crystallize directly from water. *(ex., rock salt)
Biochemical – are rocks formed by organisms or contains the remains of organisms.
Metamorphic Rocks – are rocks that form from preexisting rock that react to extreme changes in
temperature and pressure, or the addition of chemical fluids. Most of these rocks form deep within Earth.
*This process affects the structure or composition of a rock in a solid state.
*See other (separate study guide for more Metamorphic information)
Rock Cycle – is a series of natural processes that change one type of rock into another type of rock.
See diagram on page 115). *Note – the ovals represent processes and the rectangles represent materials.