Image
from article Oil sand
Tar sand deposits in Alberta. 1 mi = 1.6 km.
Search Results
Search Results
Refine this search
Search result paging links
2,191 results
Image
from article Lightning
Natural cloud-to-ground lightning near Tucson, Arizona. Note that each discharge strikes the ground in more than one place. (Photo courtesy of Michael J. Leuthold)
Image
from article Lightning
Sketches of the different types of lightning between an idealized cloud and the ground: (a) type 1, (b) type 2, (c) type 3, and (d) type 4. Channel development within the cloud is not shown. Type 1 is the most common form of cloud-to-ground…
Image
from article Lightning
Global map showing the average yearly lightning flashes per km2 from 1995 to 2013. The map is based on data collected from 1998–2013 by the Lightning Imaging Sensor (LIS) on NASA’s Tropical Rainfall Measuring Mission satellite, and from 1995–2000 by…
Image
from article Lightning
Two hundred sensor locations show the total area (shaded) that makeup the North American Lightning Detection Network. The shaded area is defined by any flash location within 600 km of a sensor. Over 30 million cloud-to-ground lightning flashes are…
Image
from article Lightning
Annual average ground flash density for the North American Lightning Detection Network is shown for 10 years, 2001–2010.
Image
from article Devonian
Devonian, the fourth period of the Paleozoic Era.
Image
from article Devonian
Biostratigraphic zones based on conodonts (left) plotted to show approximate correspondence to the chronostratigraphic stages and series which compose the Devonian System (right) and relative sea-level changes (center) showing major fluctuations…
Image
from article Devonian
Reconstruction of Middle Devonian continental positions based on distribution of lithologic climatic indicators. Probable ocean currents derived from this paleogeography explain the biogeographic realms. Kolyma and Tarim are microcontinents of the…
Image
from article Smog
Smog, Downtown Los Angeles, California, USA. (Credit: Yenwen Lu/Getty Images)
Image
from article Smog
Average background concentration of ozone in the atmosphere as a function of altitude. Note the enhancement of O3 near the Earth's surface that can occur in polluted areas as a result of photochemical smog.
Image
from article Microcline
Microcline, variety amazon stone, Pikes Peak, Colorado. (American Museum of Natural History specimen)
Image
from article Remote sensing
Landsat 8 OLI photo of wildfire smoke over Eastern Washington, United States on August 7, 2019. Landsat sensors image the Earth to assess changes in Earth’s landscape. Landsat 8 was developed jointly by NASA and the U.S. Geological Survey (USGS).…
Image
from article Remote sensing
Energy content of radiation emitted from (a) Earth and Sun and (b) atmospheric transmission due to absorption for the electromagnetic spectrum for wavelengths from 0.3 μm to 106 μm (meter scale). The Sun's energy peaks at 0.48 μm with significantly…
Image
from article Mesozoic
Mesozoic, the second era of the Phanerozoic.
Image
from article Mesozoic
Subdivisions of the Mesozoic Era, including the best age estimates and the eustatic sea-level curve depicted as relative change in coastal onlap as the shoreline moved landward (sea-level rise) or seaward (sea-level fall).
Image
from article Mesozoic
Schematic reconstruction showing paleogeography of continents, epicontinental seas, and ocean basins (arrows denote ocean currents) on Pangaea in the Mesozoic Era from the (a) Triassic (220 MYA), (b) Jurassic (155 MYA), and (c) Cretaceous (70 MYA)…
Image
from article Natrolite
Natrolite crystals on analcime. (American Museum of Natural History specimen)
Image
from article Coral reef structural complexity
A fire coral before and after bleaching, which can occur when coral are environmentally stressed. The fire coral on the left is healthy, whereas the one on the right is completely bleached. (Credit: XL Catlin Seaview Survey)
Image
from article Coral reef structural complexity
Underwater photographs of Cane Bay (St. Croix, U.S. Virgin Islands) in 1980 (left) and 2007 (right). Note the common overgrowth of fleshy macroalgae between the sparsely distributed corals in 2007 compared to the more open substrate in 1980 between…
Image
from article Coral reef structural complexity
Historical changes related to coral reef decline since the 1600s. The emergence of temperature-related responses (bleaching and disease) is coincident with the loss of urchins (Diadema) and the increase of nutrient loading.
Image
from article Coral reef structural complexity
Three dominant shallow-water communities in the waters surrounding Easter Island. (Left) Since the 1950s, fleshy algae, such as Sargassum, were the dominant cover, and coral was rare in shallow waters. (Middle) In the 1980s, global climate change…
Image
from article Map design
Figure and ground relationship. (a) Map without shading does not assist the user in isolating the subject from the background. (b, c) Map shaded in two different ways improves definition. (d) Addition of labels to show place and of the graticule…
Image
from article Map design
Design iterations created by a computer.
Image
from article Quaternary
Quaternary, the second period of the of the Cenozoic Era.
Image
from article Phanerozoic
Phanerozoic, the present geologic eon representing the past half-billion years.
Image
from article Phanerozoic
Geologic time scale showing the eons, eras, and periods of the Phanerozoic; epochs of the Cenozoic Era; and major events in the history of life. Geologic ages are given in millions of years ago (Ma). The beginning of the Archean Eon is undefined at…
Image
from article Apophyllite
Apophyllite crystals with basalt from French Creek, Pennsylvania. (From Department of Geology, Bryn Mawr College)
Image
from article Apatite
Apatite. (a) Specimen from Snarum, Norway. (b) Common crystal habits.
Image
from article Andalusite
Andalusite, variety chiastolite. Prismatic crystal specimens from Worchester County, Massachusetts. (American Museum of Natural History specimens)
Image
from article Andalusite
Phase diagram for the polymorphs of aluminum silicate (Al2SiO5). 1 km = 0.6 mi; 1 kb = 102 MPa. (After M. J. Holdaway, Stability of andalusite and the aluminum silicate phase diagram, Amer. J. Sci., 271:97–131, 1971)
Image
from article Anoxic zones
Water column profiles from Saanich Inlet, an intermittent anoxic fiord in British Columbia, Canada. (a) Oxygen and hydrogen sulfide profiles showing the interface at 130 m (430 ft). (b) Dissolved iron and manganese at the same location. Pump cast…
Image
from article Anoxic zones
Schematic representation of trends in pore water profiles. Depth and concentration are arbitrary units but represent concentrations measured or inferred (in the case of O2) in equatorial Atlantic pore waters. (After P. Froelich et al., Early…
Image
from article Marine sediments
Shoal water sediments as examples of sedimentation without supply of land-derived sediment. (a) The Bahamas. (b) The Gulf of Batabano, which is in southwestern Cuba. Both of these shoals border directly on the deep ocean.
Image
from article Marine sediments
Sediment distribution of the northwestern Gulf of Mexico as an example of the sediments of a shelf with abundant land-derived sediment. Shelf depositional sediments and slope deposits are silty clays; nondepositional area is covered with relict…
Image
from article Marine sediments
Sediments on shelves with little land-derived sediment supply. (a) Off western coast of Florida. (b) Off northwestern Yucatan Peninsula.
Image
from article Marine sediments
Distribution of deep-sea sediments. (a) Major types. (b) Kaolinite concentration. (c) Montmorillonite concentrations. The concentrations are in the <2-μm-size fraction on a carbonate-opaline-silica-free basis.
Image
from article Marine sediments
Dissolved (a) oxygen (O2) and (b) nitrate (NO3−) in the interstitial water of a pelagic marine sediment. 1 cm = 0.4 in.
Image
from article Marine sediments
Dissolved (a) nitrate (NO3−), (b) manganese (Mn), and (c) iron (Fe) in the interstitial water from a hemipelagic marine sediment. Symbols represent different cores. 1 cm = 0.4 in.
Image
from article Marine sediments
Dissolved sulfate (SO42−) and methane from extremely reducing sediments in Saanich Inlet. 1 cm = 0.4 in.
Image
from article Marine sediments
Solubility of aragonite and calcite [expressed in terms of carbonate (CO32−) ion concentration] in seawater at 2°C (36°F) as a function of water depths in the North Atlantic and the eastern Equatorial Pacific. The intersections of the solubility…
Image
from article Marine sediments
Global organic carbon cycles. DOC = dissolved organic carbon; POC = particulate organic carbon. °F = (°C × 1.8) + 32; 1 m = 3.3 ft.
Image
from article Marine sediments
Rippled seafloor of sand being transported along the bed of a thermohaline current. From a water depth of 8900 ft (2700 m) on the northwest side of the Rockall Plateau, North Atlantic.
Image
from article Marine sediments
Lead-210 (210Pb) distribution in a sediment core (527-3) obtained by the research submersible Alvin from the Famous site (36°48.5′N, 33°15.3′W) on the Mid-Atlantic Ridge. The fit of the excess 210Pb [that is, unsupported by radium-226 (226Ra)]…
Image
from article Marine sediments
Distribution of 14C ages with depth in Famous core 527-3. The top 3.5 in. (9 cm) yield a constant age of 2400 years before present (B.P.) because of bioturbation. The deeper points define a line yielding a sediment accumulation rate of 2.9 cm/103…
Image
from article Marine sediments
Summary of major changes in the climate system over the past 800,000 years from a set of 18 proxy indicators. Coherent variations are evident in all components. (After J. Imbrie et al., On the structure and origin of major glaciation cycles, 1.…
Image
from article Vesuvianite
Vesuvianite. (a) Crystal, Christiansand, Norway (specimen from Department of Geology, Bryn Mawr College). (b) Crystal habits (after C. Klein and C.S. Hurlbut, Jr., Manual of Mineralogy, 21st ed., 1993)
Image
from article Indian Ocean
Physiographic features of the Indian Ocean.
Image
from article Indian Ocean
Winds over the Indian Ocean.
Image
from article Indian Ocean
Surface currents of the Indian Ocean.
