Encyclopedia of Earth and Space Science is a two-volume reference intended to complement the material typically taught in high school Earth science and astronomy classes, and in introductory college geology, atmospheric sciences, and astrophysics courses. The substance reflects the fundamental concepts and principles that underlie the content standards for Earth and space science identified by the National Committee on Science Education Standards and Assessment of the National Research Council for grades 9-12. Within the category of Earth and space science, these include energy in the Earth system, geochemical cycles, origin and evolution of the Earth system, and origin and evolution of the universe. The National Science Education Standards (NSES) also place importance on student awareness of the nature of science and the process by which modern scientists gather information. To assist educators in achieving this goal, other subject matter discusses concepts that unify the Earth and space sciences with physical science and life science: science as inquiry, technology and other applications of scientific advances, science in personal and social perspectives including topics such as natural hazards and global challenges, and the history and nature of science. A listing of entry topics organized by the relevant NSES Content Standards and an extensive index will assist educators, students, and other readers in locating information or examples of topics that fulfill a particular aspect of their curriculum.

Encyclopedia of Earth and Space Science emphasizes physical processes involved in the formation and evolution of the Earth and universe, describes many examples of different types of geological and astro-physical phenomena, provides historical perspectives, and gives insight into the process of scientific inquiry by incorporating biographical profiles of people who have contributed significantly to the development of the sciences. The complex processes related to the expansion of the universe from the big bang are presented along with an evaluation of the physical principles and fundamental laws that describe these processes. The resulting structure of the universe, gal axies, solar system, planets, and places on the Earth are all discussed, covering many different scales of observation from the entire universe to the smallest subatomic particles. The geological characteristics and history of all of the continents and details of a few selected important areas are presented, along with maps, photographs, and anecdotal accounts of how the natural geologic history has influenced people. Other entries summarize the major branches and subdisciplines of Earth and space science or describe selected applications of the information and technology gleaned from Earth and space science research.

The majority of this encyclopedia comprises 250 entries covering NSES concepts and topics, theories, subdisciplines, biographies of people who have made significant contributions to the earth and space sciences, common methods, and techniques relevant to modern science. Entries average more than 2,000 words each (some are shorter, some longer), and most include a cross-referencing of related entries and a selection of recommended further readings. In addition, one dozen special essays covering a variety of subjects—especially how different aspects of earth and space sciences have affected people—are placed along with related entries. More than 300 color photographs and line art illustrations, including more than two dozen tables and charts, accompany the text, depicting difficult concepts, clarifying complex processes, and summarizing information for the reader. A glossary defines relevant scientific terminology. The back matter of Encyclopedia of Earth and Space Science contains a geological timescale, tables of conversion between different units used in the text, and the periodic table of the elements.

I have been involved in research and teaching for more than two decades. I am honored to be a Distinguished Professor and Yangtze Scholar at China's leading geological institution, China University of Geosciences, in Wuhan. I was formerly the P. C. Reinert Endowed Professor of Natural Sciences and am the founding director of the Center for Environmental Sciences at St. Louis University. I am actively involved in research, writing, teaching, and advising students.


My research and teaching focus on the fields of plate tectonics and the early history of the Earth, as well as on natural hazards and disasters, satellite imagery, mineral and water resources, and relationships between humans and the natural environment. I have worked extensively in North America, Asia, Africa, Europe, the Middle East, and the rims of the Indian and Pacific oceans. During this time i have authored more than 25 books, 600 research papers, and numerous public interest articles, interviews with the media (newspapers, international, national and local television, radio, and international news magazines), and i regularly give public presentations on science and society. some specific areas of current interest include the following:

• Precambrian crustal evolution

• tectonics of convergent margins

natural disasters: hurricanes, earthquakes, volcanoes, tsunami, floods, etc.

drought and desertification

• Africa, madagascar, China

• middle East geology, water, and tectonics i received bachelor and master of science degrees from the Department of Geological sciences at the state university of New York at Albany in 1982 and 1985, respectively, then continued my studies in earth and planetary sciences at the Johns Hopkins university in Baltimore. There i received a master of arts in 1988 and a Ph.D. in 1990. During this time i was also a graduate student researcher at the NAsA Laboratory for Terrestrial Physics, Goddard space Flight Center. After this i moved to the university of California at santa Barbara where i did postdoctoral research in Earth-sun-moon dynamics in the Department of mechanical Engineering. i then moved to the university of Houston for a visiting faculty position in the department of geosciences and allied geophysical laboratories at the university of Houston. in 1992 i moved to a research professor position in the Center for Remote sensing at Boston university and also took a part-time appointment as a research geologist with the u.s. Geological survey. in 2000 i moved to st. Louis university, then was appointed to a distinguished professor position at China university of Geoscience in 2009.

i have tried to translate as much of this experience and knowledge as possible into this two-volume encyclopedia. it is my hope that you can gain an appreciation for the complexity and beauty in the earth and space sciences from different entries in this book, and that you can feel the sense of exploring, learning, and discovery that i felt during the research related here, and that you enjoy reading the different entries as much as i enjoyed writing them for you.

Entries Categorized by National Science Education Standards for Content (Grades 9—12)

When relevant an entry may be listed under more than one category. For example, Alfred Wegener, one of the founders of plate tectonic theory, is listed under both Earth and space science Content standard D: origin and Evolution of the

Earth system, and Content standard D: History and Nature of science. subdisciplines are listed separately under the category subdisciplines, which is not a NsEs category, but are also listed under the related content standard category.

Science as Inquiry (Content Standard A)

astronomy astrophysics biosphere climate climate change Coriolis effect cosmic microwave background radiation cosmology Darwin, Charles ecosystem Einstein, Albert environmental geology evolution Gaia hypothesis geological hazards global warming greenhouse effect hydrocarbons and fossil fuels ice ages life's origins and early evolution mass extinctions origin and evolution of the Earth and solar system origin and evolution of the universe ozone hole plate tectonics radiation sea-level rise

Earth and Space Science (Content Standard D): Energy in the Earth System asthenosphere atmosphere aurora, aurora borealis, aurora australis black smoker chimneys climate climate change clouds convection and the Earth's mantle Coriolis effect cosmic microwave background radiation cosmic rays Earth earthquakes

Einstein, Albert

El Niño and the southern oscillation (ENso) electromagnetic spectrum energy in the Earth system Gaia hypothesis geodynamics geological hazards geomagnetism, geomagnetic reversal geyser global warming greenhouse effect hot spot hurricanes ice ages large igneous provinces, flood basalt magnetic field, magnetosphere mantle plumes mass wasting meteorology

Milankovitch cycles monsoons, trade winds ocean currents paleomagnetism photosynthesis plate tectonics precipitation radiation radioactive decay subduction, subduction zone sun thermodynamics thermohaline circulation thunderstorms, tornadoes tsunami, generation mechanisms volcano ld

Entries Categorized by National Science Education Standards for Content (Grades 9-12)

Earth and Space Science

Earth and Space Science

glacier, glacial systems

(Content Standard D):

(Content Standard D): Origin and

Gondwana, Gondwanaland

Geochemical Cycles

Evolution of the Earth System

granite, granite batholith


accretionary wedge

greenstone belts


African geology

Grenville province and Rodinia


Andes Mountains

historical geology

black smoker chimneys


hot spot

carbon cycle

Arabian geology

hydrocarbons and fossil fuels

climate change




Asian geology

igneous rocks

continental crust


impact crater structures

convection and the Earth's


Indian geology


Australian geology

island arcs, historical eruptions


basin, sedimentary basin



beaches and shorelines



benthic, benthos

large igneous provinces, flood

economic geology






environmental geology


life's origins and early evolution


cave system, cave


Gaia hypothesis



geochemical cycles

climate change


global warming

continental crust


granite, granite batholith

continental drift

mantle plumes


continental margin

mass extinctions

hydrocarbons and fossil fuels

convection and the Earth's

mass wasting




igneous rocks

convergent plate margin


large igneous provinces, flood


metamorphism and metamorphic






meteor, meteorite



Milankovitch cycles



mineral, mineralogy


crystal, crystal dislocations


mantle plumes

deformation of rocks


metamorphism and metamorphic


North American geology



ocean basin



ocean currents


divergent plate margin processes

oceanic plateau

ocean currents

drainage basin (drainage system)





ozone hole


origin and evolution of the Earth

petroleum geology

economic geology

and solar system




plate tectonics


ozone hole




river system




European geology


sedimentary rock, sedimentation






subduction, subduction zone





passive margin

thermohaline circulation


pelagic, nektonic, planktonic

thunderstorms, tornadoes





petroleum geology



petrology and petrography

Entries Categorized by National Science Education Standards for Content (Grades 9-12)

Phanerozoic photosynthesis plate tectonics Pleistocene Precambrian Proterozoic Quaternary radiation radioactive decay river system Russian geology seawater sedimentary rock, sedimentation seismology sequence stratigraphy silurian soils south American geology stratigraphy, stratification, cyclothem structural geology subduction, subduction zone subsidence sun supercontinent cycles Tertiary thermohaline circulation transform plate margin processes tsunami, generation mechanisms unconformities volcano weathering

Wegener, Alfred

Earth and Space Science

(Content Standard D):

Origin and Evolution of the Universe asteroid astronomy astrophysics binary star systems black holes comet cosmic microwave background radiation cosmic rays cosmology dark matter dwarfs (stars) Einstein, Albert galaxies galaxy clusters gravity wave ice ages interstellar medium Jupiter

Mars Mercury meteor, meteorite

Neptune nova origin and evolution of the universe planetary nebula Pluto pulsar quasar radiation radio galaxies saturn sea-level rise solar system star formation stellar evolution sun universe uranus


Science and Technology (Content Standard E)

astrophysics cosmic microwave background radiation electromagnetic spectrum Galilei, Galileo geochemistry geochronology geodesy geodynamics geographic information systems geomagnetism, geomagnetic reversal geophysics gravity wave gravity, gravity anomaly Hubble, Edwin magnetic field, magnetosphere oceanography paleomagnetism radiation remote sensing seismology telescopes thermodynamics

Science in Personal and Social Perspectives (Content Standard F)

astronomy aurora, aurora borealis, aurora australis climate change constellation cosmology

Darwin, Charles ecosystem

Einstein, Albert

El Niño and the southern oscillation (ENso) environmental geology evolution flood

Gaia hypothesis geological hazards global warming greenhouse effect hydrocarbons and fossil fuels hydrosphere island arcs, historical eruptions life's origins and early evolution mass extinctions origin and evolution of the universe sea-level rise soils subsidence sun halos, sundogs, and sun pillars supernova tsunami, historical accounts

History and Nature of Science (Content Standard G)


Bowen, Norman Levi Brahe, Tycho Cloud, Preston Copernicus, Nicolas Coriolis, Gustave Dana, James Dwight Darwin, Charles Dewey, John F. Du Toit, Alexander Einstein, Albert Eskola, Pentti Galilei, Galileo Gamow, George Gilbert, Grove K. Goldschmidt, Victor M. Grabau, Amadeus William Halley, Edmond Hess, harry Hipparchus Holmes, Arthur Hubble, Edwin Hutton, James Huygens, Christian Kepler, Johannes

Entries Categorized by National Science Education Standards for Content (Grades 9-12)


Lawson, Andrew Cooper Lemaître, Georges Lyell, sir Charles Milankovitch, Milutin M. Pettijohn, Francis John Powell, John Wesley Ptolemy, Claudius Ptolemaeus sedgwick, Adam smith, William H. sorby, henry Clifton steno, Nicolaus stille, Wilhelm hans Wegener, Alfred Werner, A. G.

Subdisciplines astronomy astrophysics atmosphere climate cosmology economic geology evolution geochemistry geochronology geodesy geodynamics geological hazards geomorphology geophysics groundwater historical geology metamorphism and metamorphic rocks meteorology mineral, mineralogy oceanography paleoclimatology paleomagnetism paleontology petroleum geology petrology and petrography plate tectonics sedimentary rock, sedimentation seismology sequence stratigraphy stratigraphy, stratification, cyclothem structural geology thermodynamics

accretionary wedge Plate tectonic theory recognizes that the surface of the Earth is broken up into a few dozen rigid plates that are all moving relative to one another by sliding along a partially molten zone deep within the mantle. These plates can have one of three types of boundaries with each other, including divergent, convergent, and transform. Divergent margins form where the plates are moving apart, convergent margins form where the plates are moving toward each other, and transform (or strike-slip) margins form where the plates are sliding past each other. Along convergent plate margins, one tectonic plate is typically pushed or subducted beneath another plate along deep oceanic trenches. In most cases a dense oceanic plate is subducted beneath a less dense, overriding continental plate, and a chain of volcanoes known as a volcanic arc forms on the overriding plate. Accretionary wedges are structurally complex parts of these subduction zone systems that form on the landward side of the trench from material scraped off from the subducting plate, as well as trench fill sediments. They typically have wedge-shaped cross sections and one of the most complex internal structures of any tectonic element known on Earth. Parts of accretionary wedges are characterized by numerous thin units of rock layers that are repeated by numerous faults, known as thrust faults, along which the same unit may be stacked upon itself many times. other parts or other wedges are characterized by a relatively large section of rocks with relatively few faults, and still other sections are dominated by folded units, packages of rocks. They also host rocks known as tectonic mélanges that are complex mixtures of blocks and thin slivers of rocks surrounded by thrust faults. The rock types in these mélanges are quite diverse and typically include greywacke, basalt, chert, and limestone, characteristically encased in a matrix of a different rock type (such as shale or serpentinite). some accretionary wedges contain small blocks or layers of high-pressure, low-temperature metamorphic rocks (known as blueschists) that have formed deep within the wedge where pressures are high and temperatures are low because of the insulating effect of the cold subducting plate. These high-pressure rocks were brought to the surface by structural processes.

Accretionary wedges grow by the gradual process of scraping sedimentary and volcanic rock material from the trench and subducting plate, which constantly pushes new material in front of and under the wedge as plate tectonics drives plate convergence. The type and style of material offscraped and incorporated into the wedge depends on the type of material near the surface on the subducting plate. subducting plates with thin layers of deep-sea sediment such as chert on their basaltic surface yield packages in the accretionary wedge dominated by basalt and chert rock types, whereas subducting plates with thick sequences of greywacke sediments yield packages (thrust slices of rock from the subducting plate) in the accretionary wedge dominated by greywacke. Prisms of accreted rock at convergent plate boundaries may also grow by a process known as underplat-ing, where packages are added to the base of the accretionary wedge, a process that typically causes folding of the overlying parts of the wedge. The fronts or toes of accretionary wedges are also characterized by material slumping off of the steep slope of the wedge into the trench. This material can then be recycled back into the accretionary wedge to form even more complex structures. The processes of off-

scraping and underplating work together and rotate rock layers and structures to steeper orientations. In this way rock layers rotate from an orientation that is near horizontal at the toe of the wedge, to near vertical at the back of the wedge.

Accretionary wedges are thought to behave mechanically somewhat as if they were piles of sand or snow bulldozed in front of a plow. They grow into a triangular wedge shape in cross section that increases its slope until it becomes oversteepened and mechanically unstable, which then causes the toe of the wedge to advance by thrusting, or the top of the wedge to collapse by normal faulting. Either of these two processes can reduce the slope of the wedge and lead it to become more stable. In addition to the evidence for thrust faulting in accretionary wedges, structural geologists have documented many examples of normal faults where the tops of the wedges have collapsed, supporting models of extensional collapse of oversteepened wedges.

Accretionary wedges are forming above nearly every subduction zone on the planet. However, these accretionary wedges presently border open oceans that have not yet closed by plate tectonic processes. Eventually the movements of the plates and continents will cause the accretionary wedges to become involved in plate collisions that will dramatically change the character of the accretionary wedges. They are typically overprinted by additional shortening, faulting, folding, and high-temperature meta-morphism, and intruded by magmas related to arcs and collisions. These later events, coupled with the initial complexity and variety, make identification of accretionary wedges in ancient mountain belts difficult, and prone to uncertainty.


Southern Alaska is underlain by a complex assemblage of accreted terranes, including the Wrangellia superterrane (consisting of three separate terranes called the Peninsular, Wrangellia, and Alexander terranes), and farther outboard, the Chugach-Prince William superterrane. During much of the Meso-

Folding Faulting Making Things

Offscraping: dewatering and stratal disruption Fault zone development Underplating

O Infobase Publishing

Offscraping: dewatering and stratal disruption Fault zone development Underplating

O Infobase Publishing

Cross section of typical accretionary wedge, showing material being offscraped at the toe of the wedge and underplated beneath the wedge. Water escapes upward through the accretionary wedge, causing the wedge material to become denser and more compacted.

zoic, the two superterranes formed a magmatic arc and accretionary wedge, respectively, above a cir-cum-Pacific subduction zone. The Border Ranges fault forms the boundary between the Wrangellia and Chugach-Prince William superterranes; it initiated as a subduction thrust but has been reactivated in various places as a strike-slip or normal fault. On the Kenai Peninsula the Chugach terrane contains two major units. The unit located farther inland, the McHugh complex, is composed mainly of basalt, chert, argillite, and greywacke, as well as several large ultramafic massifs. Pinhead-sized marine fossils called radiolarians from McHugh cherts throughout south-central Alaska range in age from middle Triassic to middle Cretaceous. The interval during which the McHugh complex formed by subduction and accretion is not well known but probably spanned most of the Jurassic and Cretaceous. The McHugh has been thrust seaward on the Eagle River/Chugach Bay fault over a relatively coherent tract of trench turbidites assigned to the Upper Cretaceous Valdez Group. After the protracted episode of subduction-accretion that built the Chugach terrane, the accretionary wedge was cut by near-trench intrusive rocks, assigned to the Sanak-Baranof plutonic belt, probably related to ridge subduction.

The McHugh complex of south-central Alaska and its lateral equivalent, the Uyak complex of Kodiak, are part of the Mesozoic/Cenozoic accretion-ary wedge of the Chugach terrane. The vast extent of the McHugh complex has proven to be of value in reconstructing the tectonics of the Pacific realm and has been compared with similar tracts such as the Franciscan complex of California and the Shimanto Belt of Japan. The evolution of the McHugh and its equivalents can be broken down into three broad, somewhat overlapping phases: (1) origin of igneous and sedimentary rocks; (2) incorporation into the subduction complex ("accretion"), and attendant deformation and metamorphism; and (3) younger deformations.

Few fossil ages have been reported from the McHugh complex, but at several places on the Kenai Peninsula radiolarian chert depositionally overlies pillow basalt. Precise radiolarian age calls show that the base of the chert varies in age from middle Trias-sic to middle Cretaceous. Greywacke depositionally overlying chert has yielded Early Jurassic radiolar-ians. These ages are readily explained by a strati-graphic model in which the McHugh basalts were formed by seafloor spreading, the overlying cherts were deposited on the ocean floor as it was conveyed toward a trench, and the argillite and greywacke record deposition in the trench, just prior to subduc-tion-accretion. The timing of subduction-accretion is not well known but probably spanned most of the Jurassic and Cretaceous.

Limestones within the McHugh complex are of two categories. A limestone clast in McHugh conglomerate has yielded conodonts with a possible age range of Late Mississippian to Early Pennsylvanian. This clast could have been shed from the Wrangellia terrane. Most of the dated limestones, however, are tectonic blocks typically occurring as severely extended strings of boudins that have yielded Permian fusulinids or conodonts. Both the fusulinids and conodonts are of shallow-water, tropical, Tethyan affinity; the fusulinids are quite distinct from those of Wrangellia. The limestone blocks might represent the tops of seamounts that were decapitated at the subduction zone. If so, some of the ocean floor offscraped to form the McHugh complex must have formed in the Paleozoic.

The seaward part of the Chugach terrane is underlain by the Valdez group of Late Cretaceous age. On the Kenai Peninsula it includes medium- and thin-bedded greywacke turbidites, black argillite, and minor pebble to cobble conglomerate. These strata were probably deposited in a deep-sea trench and accreted shortly thereafter. Most of the Valdez group consists of relatively coherent strata, deformed into regional-scale tight- to isoclinal folds, cut by a slaty cleavage. The McHugh complex and Valdez group are juxtaposed along a thrust, which in the area of Turnagain Arm has been called the Eagle River fault, and on the Kenai Peninsula is known as the Chugach Bay thrust. Beneath this thrust is a mélange of partially to thoroughly disrupted Valdez group turbidites. This monomict mélange, which is quite distinct from the polymict mélanges of the McHugh complex, can be traced for many kilometers in the footwall of the Eagle River thrust and its along-strike equivalents.

In early Tertiary time, the Chugach accretionary wedge was cut by near-trench intrusive rocks forming the Sanak-Baranof plutonic belt. The near-trench magmatic pulse migrated 1,370 miles (2,200 km) along the continental margin, from about 63-65 million years ago at sanak Island in the west, to about 50 million years ago at Baranof Island in the east. The Paleogene near-trench magmatism was related to subduction of the Kula-Farallon spreading center.

Mesozoic and Cenozoic rocks of the accretion-ary wedge of south-central Alaska are cut by abundant late brittle faults. Along Turnagain Arm near Anchorage, four sets of late faults are present: a conjugate pair of east-northeast-striking dextral and northwest-striking sinistral strike-slip faults, north-northeast-striking thrusts, and less abundant west-northwest-striking normal faults. All four fault sets are characterized by quartz ± calcite ± chlorite fibrous slickenside surfaces and appear to be approximately coeval. The thrust- and strike-slip faults together resulted in subhorizontal shortening perpendicular to strike, consistent with an accretionary wedge setting. Motion on the normal faults resulted in extension of the wedge but is of uncertain tectonic significance. Some of the late brittle faults host gold-quartz veins that are the same age as nearby near-trench intrusive rocks. By implication, the brittle faulting and gold mineralization are probably related to ridge subduction.

Scattered fault-bounded ultramafic-mafic complexes in southern Alaska stretch 600 miles (1,000 km) from Kodiak Island in the south to the Chugach Mountains in the north. These generally consist of dunite +/- chromite, several varieties of peridotite, which grade upward into gabbronorites. These rocks are intruded by quartz diorite, tonalite, and grano-diorite. Because of general field and mineralogic similarities, these bodies are generally regarded as having a similar origin and are named the Border Ranges ultramafic-mafic complex (BRUMC). The BRUMC includes six bodies on Kodiak and Afognak Islands, plus several on the Kenai Peninsula (including Red Mountain) and other smaller bodies. In the northern Chugach Mountains the BRUMC includes the Eklutna, Wolverine, Nelchina, and Tonsina complexes, and the Klanelneechena complex in the central Chugach Mountains.

Some models for the BRUMC suggest that all these bodies represent cumulates formed at the base of an intraoceanic arc sequence, and were formed at the same time as volcanic rocks now preserved on the southern edge of the Wrangellian composite terrane located in the Talkeetna Mountains. Some of the ultramafic massifs on the southern Kenai Peninsula, however, are not related to this arc, but represent deep oceanic material accreted in the trench. The ultramafic massifs on the Kenai Peninsula appear to be part of a dismembered assemblage that includes the ultramafic cumulates at the base, gabbroic-basalt rocks in the center, and basalt-chert packages in the upper structural slices. The ultramafic massifs may represent pieces of an oceanic plate subducted beneath the Chugach terrane, with fragments off-scraped and accreted during the subduction process. There are several possibilities as to what the oceanic plate may have been, including normal oceanic lithosphere, an oceanic plateau, or an immature arc. Alternatively, the ultramafic/mafic massifs may represent a forearc or suprasubduction zone ophiolite, formed seaward of the incipient Talkeetna (Wrangel-lia) arc during a period of forearc extension.

See also Asian geology; convergent plate margin processes; deformation of rocks; mélange; plate tectonics; structural geology.


Bradley, Dwight C., Timothy M. Kusky, Peter Haeussler, D. C. Rowley, Richard Goldfarb, and S. Nelson. "Geologic Signature of Early Ridge Subduction in the Accretionary Wedge, Forearc Basin, and Mag-matic Arc of South-Central Alaska." In Geology of a Transpressional Orogen Developed During a Ridge-Trench Interaction Along the North Pacific Margin, edited by Virginia B. Sisson, Sarah M. Roeske, and Terry L. Pavlis. Geological Society of America Special Paper 371 (2003): 19-50.

Bradley, Dwight C., Timothy M. Kusky, Peter Haeussler, S. M. Karl, and D. Thomas Donley. "Geologic Map of the Seldovia Quadrangle, United States Geological Survey Open File Report 99-18, scale 1:250,000, with marginal notes, 1999." Available online. URL: Accessed october 25, 2008.

Burns, L. E. "The Border Ranges Ultramafic and Mafic Complex, South-Central Alaska: Cumulate Fractionates of Island Arc Volcanics." Canadian Journal of Earth Science 22 (1985): 1,020-1,038.

Connelly, W. "Uyak Complex, Kodiak Islands, Alaska—A Cretaceous Subduction Complex." Geological Society of America Bulletin 89 (1978): 755-769.

Cowan, Darrel S. "Structural Styles in Mesozoic and Ceno-zoic Mélanges in the Western Cordillera of North America." Geological Society of America Bulletin 96 (1985): 451-462.

Hatcher, Robert D. Structural Geology, Principles, Concepts, and Problems. 2nd ed. Englewood Cliffs, N.J.: Prentice Hall, 1995.

Hudson, Travis. "Calc-Alkaline Plutonism along the Pacific Rim of Southern Alaska: Circum-Pacific Terranes." Geological Society of America Memoir 159 (1983): 159-169.

Kusky, Timothy M., and Dwight C. Bradley. "Kinematics of Mélange Fabrics: Examples and Applications from the McHugh Complex, Kenai Peninsula, Alaska." Journal of Structural Geology 21, no. 12 (1999): 1,773-1,796.

Kusky, Timothy M., Dwight C. Bradley, D. Thomas Donley, D. C. Rowley, and Peter Haeussler. "Controls on Intrusion of Near-Trench Magmas of the Sanak-Baranof Belt, Alaska, during Paleogene Ridge Subduction, and Consequences for Forearc Evolution." In "Geology of a Transpressional Orogen Developed During a Ridge—Trench Interaction Along the North Pacific Margin," edited by Virginia B. Sisson, Sarah M. Roeske, and Terry L. Pavlis. Geological Society of America Special Paper 371 (2003): 269-292.

Kusky, Timothy M., Dwight C. Bradley, Peter Haeussler, and S. Karl. "Controls on Accretion of Flysch and Mélange Belts at Convergent Margins: Evidence from the Chugach Bay Thrust and Iceworm Mélange,

Chugach Terrane, Alaska." Tectonics 16, no. 6 (1997): 855-878.

Kusky, Timothy M., Dwight C. Bradley, and Peter Hae-ussler. "Progressive Deformation of the Chugach Accretionary Complex, Alaska, during a Paleogene Ridge-Trench Encounter." Journal of Structural Geology 19, no. 2 (1997): 139-157. Plafker, George, and H. C. Berg. "Overview of the Geology and Tectonic Evolution of Alaska." In The Geology of Alaska, Decade of North American Geology, G-1, edited by G. Plafker and H. C. Berg. Boulder, Colo.: Geological Society of America, 1994, 389-449. Plafker, George, James C. Moore, and G. R. Winkler. "Geology of the Southern Alaska Margin." In The Geology of Alaska, Decade of North American Geology, G-1, edited by G. Plafker and H. C. Berg. Geological Society of America (1994): 989-1,022. van der Pluijm, Ben A., and Stephen Marshak. Earth Structure: An Introduction to Structural Geology and Tectonics. Boston: WCB-McGraw Hill, 1997.

African geology The continent of Africa consists of several old nuclei of very old (Archean) rocks called cratons that were welded together along younger (Proterozoic) mountain belts called oro-genic belts that formed during collision of the cra-tons in the Late Precambrian. The cratons include the intensely studied Kalahari craton, comprising two Archean cratons known as the Kaapvaal and Zimbabwe cratons, plus the less well-known Congo and West African cratons. The Madagascar craton, which used to be attached to the African continent, lies off the coast of East Africa. These cratons are sutured along orogenic belts colloquially known as Pan African orogens, a term that is sometimes used to refer to the belts of rocks affected by complex igneous, metamorphic, and structural events that cut across Africa and many other continental masses between about 1,000 and 500 million years ago. The northern and southern margins of the African continent are affected by Paleozoic-Mesozoic deformation and mountain building, and the eastern side of the continent is experiencing active rifting and breakup into microplates, one of which extends through Madagascar and links with the Indian-Australian ridge.

Continue reading here: Kalaharicraton

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