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TitleHandbook Rocks
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Table of Contents
                            TITLE
COPYRIGHT
CONTENTS
INTRODUCTION
CHAPTER 1 A WORLD OF ROCK
	GENERAL CONSIDERATIONS
	TEXTURE
		CLASSIFICATION BY GRAIN OR CRYSTAL SIZE
		POROSITY
	PHYSICAL PROPERTIES
		DENSITY
		MECHANICAL PROPERTIES
		THERMAL PROPERTIES
		ELECTRICAL PROPERTIES
		MAGNETIC PROPERTIES
CHAPTER 2 IGNEOUS ROCK
	COMPOSITION
		CHEMICAL COMPONENTS
		MINERALOGICAL COMPONENTS
	TEXTURAL FEATURES
		CRYSTALLINITY
		GRANULARITY
	STRUCTURAL FEATURES
		SMALL-SCALE STRUCTURAL FEATURES
		LARGE-SCALE STRUCTURAL FEATURES
	CLASSIFICATION OF IGNEOUS ROCKS
		CLASSIFICATION OF PLUTONIC ROCKS
		CLASSIFICATION OF VOLCANIC AND HYPABYSSAL ROCKS
	ORIGIN AND DISTRIBUTION
		ORIGIN OF MAGMAS
		NATURE OF MAGMAS
		CRYSTALLIZATION FROM MAGMAS
		VOLATILE CONSTITUENTS AND LATE MAGMATIC PROCESSES
	FORMS OF OCCURENCE
		EXTRUSIVE IGNEOUS ROCKS
		INTRUSIVE IGNEOUS ROCKS
		DISTRIBUTION OF IGNEOUS ROCKS ON EARTH’S SURFACE
CHAPTER 3 SEDIMENTARY ROCK
	CLASSIFICATION SYSTEMS
		TERRIGENOUS CLASTIC ROCKS
		CARBONATE ROCKS: LIMESTONES AND DOLOMITES
		NONCARBONATE CHEMICAL SEDIMENTARY ROCKS
	TEXTURE
		GRAIN SIZE
		PARTICLE SHAPE
		FABRIC
	MINERALOGICAL AND GEOCHEMICAL COMPOSITION
	SEDIMENTARY STRUCTURES
		EXTERNAL STRATIFICATION
		BEDDING TYPES AND BEDDING-PLANE FEATURES
		DEFORMATION STRUCTURES
	SEDIMENTARY ENVIRONMENTS
	SEDIMENTARY ROCK TYPES
		CONGLOMERATES AND BRECCIAS
		SANDSTONES
		MUDROCKS
		LIMESTONES AND DOLOMITES
		SILICEOUS ROCKS
		PHOSPHORITES
		EVAPORITES
		IRON-RICH SEDIMENTARY ROCKS
		ORGANIC-RICH SEDIMENTARY DEPOSITS
	SECULAR TRENDS IN THE SEDIMENTARY ROCK RECORD
CHAPTER 4 METAMORPHIC ROCK
	METAMORPHIC VARIABLES
		TEMPERATURE
		PRESSURE
		ROCK COMPOSITION
	METAMORPHIC REACTIONS
		REACTIONS IN A KAOLINITE-QUARTZ SYSTEM
		REACTIONS OF OTHER MINERAL SYSTEMS
		ISOGRADS
		PRINCIPAL TYPES
		RETROGRADE METAMORPHISM
	TEXTURAL FEATURES
		MAJOR FEATURES
		LAMINATION
	STRUCTURAL FEATURES
	METAMORPHIC FACIES
		FACIES SERIES
		PRESSURE-TEMPERATURE-TIME PATHS
	ORIGIN OF METAMORPHIC ROCKS: TYPES OF METAMORPHISM
		HYDROTHERMAL METAMORPHISM
		DYNAMIC METAMORPHISM
		CONTACT METAMORPHISM
		REGIONAL METAMORPHISM
	DISTRIBUTION OF METAMORPHIC ROCKS
	CLASSIFICATION OF METAMORPHIC ROCKS
		SCHIST
		SLATE
		GNEISSES
		HORNFELS
		MARBLE
		MYLONITES AND CATACLASTITES
		OTHER CLASSES
	CONCLUSION
APPENDIX: GEOLOGIC TIME SCALE
GLOSSARY
BIBLIOGRAPHY
	ROCKS
	IGNEOUS ROCKS
	SEDIMENTARY ROCKS
	METAMORPHIC ROCKS
INDEX
BACK COVER
                        
Document Text Contents
Page 148

129

form authigenically at the site of deposition. Some of the
important clay minerals are kaolinite, halloysite, mont-
morillonite, illite, vermiculite, and chlorite.

The mean chemical composition of the major varieties
of sedimentary rocks exhibits wide variation. Significant
contrasts in overall composition among sandstones, car-
bonates, and mudrocks reflect fundamental differences
not only in the mechanisms by which detrital minerals of
different sizes are transported and deposited but also in
the chemical conditions that permit precipitation of vari-
ous authigenic minerals.

Diagenesis includes all physicochemical, biochemi-
cal, and physical processes (short of metamorphism) that
modify sediments in the time between their deposition
and their analysis. Lithification, the process by which
sediment is converted into solid sedimentary rock, is one
result of diagenesis. Many diagenetic processes such as
cementation, recrystallization, and dolomitization are
essentially geochemical processes; others such as compac-
tion are fundamentally physical processes. All diagenetic
changes occur at the low temperatures and pressures char-
acteristic of surface and near-surface environments. These
changes can take place almost immediately after sediment
formation, or they can occur hundreds or even millions of
years later.

SEDIMEnTARy STRUCTURES

Sedimentary structures are the larger, generally three-
dimensional physical features of sedimentary rocks; they
are best seen in outcrop or in large hand specimens rather
than through a microscope. Sedimentary structures
include features such as bedding, ripple marks, fossil tracks
and trails, and mud cracks. They conventionally are subdi-
vided into categories based on mode of genesis. Structures

7 Sedimentary rock 7

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130

that are produced at the same time as the sedimentary
rock in which they occur are called primary sedimentary
structures. Examples include bedding or stratification,
graded bedding, and cross-bedding. Sedimentary struc-
tures that are produced shortly after deposition and as a
result of compaction and desiccation are called penecon-
temporaneous sedimentary structures. Examples include
mud cracks and load casts. Still other sedimentary struc-
tures such as concretions, vein fillings, and stylolites form
well after deposition and penecontemporaneous modifi-
cation; these are known as secondary structures. Finally,
others such as stromatolites and organic burrows and
tracks, though they may in fact be primary, penecontem-
poraneous, or even secondary, may be grouped as a fourth
category—organic sedimentary structures.

Considerable attention is paid to the sedimentary
structures exhibited by any sedimentary rock. Primary sed-
imentary structures are particularly useful because their
abundance and size suggest the probable transporting and
depositional agents. Certain varieties of primary sedimen-
tary structures like cross-bedding and ripple marks display
orientations that are consistently related to the direction
of current movement. Such structures are referred to as
directional sedimentary structures because they can be
used to infer the ancient paleocurrent pattern or dispersal
system by which a sedimentary rock unit was deposited.
Other sedimentary structures are stratigraphic “top and
bottom” indicators. For example, the progressive upward
decrease in clastic grain size diameters, known as graded
bedding, would allow a geologist to determine which way
is stratigraphically “up”—i.e., toward the younger beds in
a dipping sedimentary bed. The suite (repeated sequence)
of sedimentary structures in any single stratigraphic unit
is another attribute by which that unit may be physically
differentiated from others in the region.

Page 295

7 rocks 7

276

titanium, 81, 200
trenches, 106, 107, 115, 158–159, 248
Triassic Period, 36, 178
tridymite, 57, 67, 68, 230
tuffs, 64, 65, 80, 143

U
Udden-Wentworth scale, 7, 124
ultramafic rocks, 54, 56–57, 58,

74, 104, 110, 200, 244
Uluru, 145–146
unroofing, 197, 237
uplift, 155, 184, 196, 197, 212,

224–225, 235
uranium, 32, 83, 163

V
viscosity, 23, 85, 95, 98
void space, 8, 9–10, 19
volatile constituents, 87, 94–96
volcanic rocks, 52, 56, 58, 60,

62–63, 67–68, 71, 72, 79–81,
97–98, 155

volcanoes, 7, 50, 53, 64–65, 86,
97, 99–100, 103, 104, 105,
106, 107

volume, 8–10, 12

W
wackes, 156–159
Walther, Johannes, 136–137

water
currents, 127, 131, 133, 134, 139,

141, 147, 148, 150, 156–157
electrical conduction and, 39
formation of, 53, 210
groundwater, 10, 58, 111, 116,

179, 182, 228
magnetization and, 44
measurements and, 124
pressure of, 242, 244
rock formation and, 3, 4, 5, 59,

68, 71, 81, 85, 94–95, 97–98,
100, 111, 131, 136, 139, 161,
170, 180, 200, 206

running, 3, 112, 131
seawater, 16, 37, 171, 172, 174,

178, 190
temperature and, 13, 31, 84, 88,

94–95, 213
weathering, 5, 52, 111, 112
Wegener, Alfred, 36
wind, 3, 65, 111, 112, 131, 148, 150,

151, 161

Y
Young’s modulus, 17, 18

Z
zeolite, 59, 67, 96, 160, 238, 239, 248
zeolite facies, 239
zircon, 58, 153, 161
zonal structures, 72

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