Rocks: Materials of the Solid Earth
opens with a discussion of the rock cycle as part of the Earth system. The
origins and processes involved in forming the three major rock groups – igneous rock, sedimentary rock, and
metamorphic rock – are also reviewed. A discussion of the crystallization of magma precedes an examination
of the classification, textures, and compositions of igneous rocks. Following an investigation of the origin of
sediment, the classification of sedimentary rocks, as well as some of their common features, is discussed. The
chapter also examines the agents of metamorphism, the textural and mineralogical changes that take place
during metamorphism, and some common metamorphic rocks. In conclusion, resources from rocks and
minerals are investigated.
After reading, studying, and discussing the chapter, students should be able to:
Diagram and discuss the rock cycle
List the geologic processes involved in the formation of each rock group.
Briefly explain crystallization of magma.
List the criteria used to classify igneous rocks.
List the names, textures, and environments of formation for the most common igneous rocks.
Discuss the origin of materials that accumulate as sediment.
List the criteria used to classify sedimentary rocks.
Explain the difference between detrital and chemical sedimentary rocks.
List the names, textures, and environments of formation for the most common sedimentary rocks.
List the common features of sedimentary rocks.
Describe the agents of metamorphism.
List the criteria used to classify metamorphic rocks.
List the names, textures, and environments of formation for the most common metamorphic rocks.
Discuss metallic and nonmetallic mineral resources
that cools and solidifies in a process called
forms from the
forms from rock that has been subjected to
great pressure and heat in a process called
The rate of cooling of magma greatly influences the size of mineral crystals in igneous rock – the faster the
rate of cooling, the smaller the crystals. The four basic igneous rock textures are 1)
, and 4)
The mineral makeup of an igneous rock is ultimately determined by the chemical composition of the
magma from which it crystallized. N.L. Bowen showed that as magma cools, minerals crystallize in an
can change the composition of magma and cause more than one rock type to
form from a common parent magma.