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from article Continental drift
Map of the Earth as Pangea broke up as a result of continental drift. (Copyright © McGraw-Hill)
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from article Sturgeon
Shovelnose sturgeon (Scaphirhynchus platorynchus). (Photo by Konrad Schmidt)
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from article Stalactites and stalagmites
Stalactite and stalagmite deposits. Along the central opening are deposits made by water as it dripped from the crack in the limestone. Outside layers were deposited by water flowing over the surface. Water may drip to the floor and create a…
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from article Relativistic heavy-ion collisions
High-energy nuclear collision. The participant nucleons in the projectile and target transiently form a hot and dense fireball, while the spectator nucleons remain relatively undisturbed. The fireball will subsequently expand and emit a large number…
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from article Lake
MODIS (MODerate-resolution Imaging Spectroradiometer) Terra satellite image of the Great Lakes, September 15, 2015. (Credit: NOAA Great Lakes CoastWatch)
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from article Lake
Oxbows in Bolivia. Landsat satellite image of the Beni River in Bolivia, which resembles a blue ribbon as it flows toward the Amazon River. Scattered along the river are numerous oxbow lakes, which are curved bodies of water that form when a meander…
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from article Epitaxial structures
Matching of lattice planes between the substrate and the epitaxial layer by (a) expansion or contraction of lattice plane, (b) in-plane rotation, and (c) tilting (out-of-plane rotation).
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from article Epitaxial structures
Misfit accommodation occurs (a) between the epitaxial layer and the substrate through the presence of interfacial misfit dislocations and (b) by atomic steps at an interface where the epitaxial film is tilted with respect to the substrate.
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from article Epitaxial structures
Schematic illustration of the tetragonal distortion effect to accommodate purely dilational strained-layer epitaxial structure.
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from article Epitaxial structures
Modes of epitaxial growth: (a) Frank–van der Merwe mode producing a complete wetting of epitaxial layers. (b) Volmer-Weber mode with totally incomplete wetting resulting in an island growth structure. (c) Stranski- Krastanov mode with initial layer…
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from article Oil shale
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from article Oil shale
C-13 nuclear magnetic resonance characterization of organic matter in two United States oil shale samples. (a) Colorado oil shale, 80% aliphatic carbon content with 69% conversion of organic carbon to oil. (b) Kentucky oil shale, 52% aliphatic…
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from article Oil shale
Oil shale deposits of the United States. (Courtesy of John Ward Smith)
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from article Oil shale
Oil shale retorting systems: (a) internally heated, (b) externally heated.
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from article Camel
Bactrian camel (Camelus bactrianus). (Photo courtesy of Brent Huffman, Ultimate Ungulate Images)
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from article Hydrothermal vent
Black smoker plume at a hydrothermal vent. Black smoker vents are distinguished by the presence of such large quantities of minute mineral particles that the plumes become virtually opaque. The minerals solidify as they cool, forming chimney-like…
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from article Hydrothermal vent
Schematic view of the seawater circulation system creating hydrothermal vents along a mid-oceanic ridge.
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from article Hydrothermal vent
Giant Riftia tubeworms from warm vents at the Galápagos Rift vent site. These tubeworms reach lengths of at least 2 m (6 ft).
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from article Spelaeogriphacea
Lateral and dorsal views of the Western Australian spelaeogriphacean species Mangkurtu mityula.
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from article Electroluminescence
Structure of powdered-phosphor (Destriau) electroluminescent cell, edge view (not to scale).
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from article Electroluminescence
Structure of a thin-film electroluminescent matrix display. (After J. Kuwata et al., Feasibility of a 40 × 40 cm2 TFEL display with 2000 × 2000 lines operating at 50W, Society for Information Display Digest, pp. 297–300, 1988)
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from article Electroluminescence
Brightness-voltage characteristics of some zinc sulfide thin-film electroluminescent devices as a function of activator, insulating film, and operating frequency. (After R. Mach and G. O. Müller, Physical concepts of high-field thin-film…
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from article Dendrochronology
Ring patterns showing complacent and sensitive ring series. (a) Climate has minimal effect on ring widths when trees have ample moisture every year. (b) Maximum ring-width variations occur on sites where growth is limited by factors that vary from…
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from article Dendrochronology
Core being taken from a tree with an increment borer. (Courtesy of Laboratory of Tree-Ring Research, University of Arizona)
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from article Dendrochronology
Chronology building. Chronologies are extended backward in time by matching patterns of wood samples whose ages overlap.
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from article Dendrochronology
Skeleton plot (top) from an idealized tree-ring sequence in a specimen (bottom). Ring widths are represented by vertical lines in inverse proportion; that is, tall lines represent narrow rings. An exceptionally wide ring is designated by the letter…
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from article Dendrochronology
Bristlecone pines, which attain ages of more than 4000 years, form the basis for the second longest chronology yet developed. (Courtesy of Laboratory of Tree-Ring Research, University of Arizona)
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from article Diplomonadida
A diplomonad, Trepomonas rotans.
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from article Quantum chromodynamics
Screening in electrodynamics. (a) Polarization of a dielectric medium by a test charge. (b) Feynman diagram contributing to vacuum polarization.
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from article Quantum chromodynamics
Screening and antiscreening in quantum chromodynamics. (a) Screening of a colored quark by vacuum polarization. Color charges are denoted by R = red, R = anti-red, B = blue, B = anti-blue, G = green, G = anti-green. (b) Feynman diagram contributing…
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from article Quantum chromodynamics
High-energy proton-antiproton collisions. (a) Parton-model description of a violent collision between constituents of a proton and an antiproton. The active particles may be quarks, antiquarks, or gluons. (b) The most energetic two-jet event yet…
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from article Quantum chromodynamics
Structure of the proton as observed with probes of increasing resolution. (a) Quarks appear as simple and noninteracting objects under “low magnification.” (b–d) Quarks reveal increasing complexity because of their interactions with gluons as…
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from article Quantum chromodynamics
Spectra of bound particle-antiparticle systems. (a) Positronium. (b) ψ/J family, known as charmonium.
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from article Global climate change
Fossil-fuel-burning power plant—a source of greenhouse-gas emissions. (Credit: Schroptschop/Getty Images)
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from article Global climate change
Climate models run with natural factors alone (for example, solar and volcanic activity) fail to produce results that align with observations. The top left panel shows annual global average surface temperature anomalies (the difference between the…
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from article Global climate change
Atmospheric concentrations of carbon dioxide (CO2) in parts per million (ppm) (top panel), methane (CH4) in parts per billion (ppb) (middle panel), and nitrous oxide (N2O) in parts per billion (ppb) (bottom panel) over the past 800,000 years (left…
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from article Global climate change
Annual global average surface temperature anomalies (difference between the annual value and the 1951–1980 average) in degrees Celsius over the period from 1880 to 2017. (Data source: NASA/GISS, 2018)
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from article Global climate change
Contributions to observed global average surface temperature change (black bar) over the period 1951–2010 in degrees Celsius. Green bar: greenhouse-gas emissions. Yellow bar: other human-caused drivers (including aerosol emissions and…
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from article Dacite
Photomicrograph of a dacite from the Zitacuaro– Valle de Bravo region of central Mexico. P = plagioclase, O = orthopyroxene (hypersthene), A = augite, G = glassy groundmass.
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from article Dacite
Dacite domes from the Zitacuaro volcanic complex of central Mexico. (Photo by D. Blatter)
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from article Semiconductor
Energy diagram of a surface barrier as employed in an n-type semiconductor.
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from article Semiconductor
Energy diagram for a metal (left) and an n-type semiconductor (right). E0 is the potential energy of an electron outside the material, Ec is the energy at the bottom of the conduction band, and Ev is the energy at the top of the valence band. (a)…
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from article Semiconductor
Energy diagrams of a rectifying contact between a metal and a semiconductor: (a) n-type semiconductor; (b) p-type semiconductor.
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from article Semiconductor
Energy diagrams of a rectifying contact between a metal and an n-type semiconductor under an applied voltage V. (a) Positive semiconductor. There is a net flow of electrons from metal to semiconductor. (b) Negative semiconductor. There is a net flow…
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from article Perthite
Schematic showing the development of two perthitic intergrowth textures. (After G. W. Lorimer and P. E. Champness, The origin of the phase distribution in two perthitic alkali feldspars, Philos. Mag., 28:1401, 1973)
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from article Runge vector
Runge vector for elliptical motion (R = λm · a2−b2/a).
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from article Y-delta transformations
Three-terminal star, or Y.
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from article Y-delta transformations
Three-terminal mesh, or Δ.
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from article Y-delta transformations
Three-terminal star and mesh drawn as T and π.
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from article Y-delta transformations
Diagram to show the pattern of subscripts used in equations.
