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Listing 21 - 30 of 252 results.

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Photo ID: h32dzgSubject: PaleontologyDescription
Holocene; Ice Caps; Ice Cores; Last Glacial Maximum; Paleoclimatology; PleistoceneThe most prominent feature in the Dunde ice record is the transition between the Last Glacial Maximum (in the Pleistocene epoch) and the present Holocene epoch. Less negative oxygen-18 to oxygen-16 ratio measurements suggest that temperatures were cooler in the Qinghai-Tibetan Plateau during the Pleistocene, while high particle concentrations show that conditions were much dustier. Very low concentrations of nitrate, chloride, and sulfate during the glacial period may reflect higher precipitation rates during the Last Glacial Maximum.

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PhotographerLocation
NOAA

Credit Line: Courtesy National Oceanic and Atmospheric Administration
Asia; China; Qinghai; Dunde Ice Cap
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32e2mSubject: GlaciersDescription
Drilling; Ice Ages; Ice Caps; Ice Cores; PaleoclimatologyAfter hauling their equipment to 5325 meters above sea level, scientists set up a small gas-powered drill. While there are minor variations in drilling technology and techniques, all drills use the same basic idea: a drill bit is lowered into the core hole and cuts out a cylinder of ice that is then carefully extracted from the core sleeve and analyzed both on site and in the laboratory. Since snow accumulates more slowly at the Dunde Ice Cap in China, ice from its 140 meter cores is significantly older than that from Quelccaya in the Peruvian Andes. While Quelccaya provides high-resolution clues to the last 1500 years of climate, Dunde stretches back over 40,000 years, well into the last ice age.
PhotographerLocation
NOAA

Credit Line: Courtesy National Oceanic and Atmospheric Administration
Asia; China; Qinghai; Dunde Ice Cap
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32ehcSubject: EnvironmentDescription
Agriculture; Arid Environment; Climate; Electrical Conductivity; Ice Caps; Ice Cores; Peruvian Civilizations; Pluvial Environment; RainfallPre-historic Peruvian civilizations were predicated on agriculture. The relatively dense population depended on intensive cultivation for food, while the rulers of powerful empires like that of the Inca demanded a large agricultural surplus to underwrite their political apparatus. Successful agriculture, in turn, depended on climate. The Peruvian coast is an exceptionally dry place, and coastal civilizations could only rise during pluvial (rainy) periods. Highland cultures, on the other hand, raised crops near their elevational and climatic limit (the altiplano, it should be remembered, is higher than most Rocky Mountain peaks). Because of their dependence on cultivating crops in climatically sensitive areas, Peruvian civilizations rose and fell to the oscillations of climate.
PhotographerLocation
NOAA

Credit Line: Courtesy National Oceanic and Atmospheric Administration
South America; Peru; Altiplano; Quelccaya Ice Cap
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32ekfSubject: GlaciersDescription
Ice Caps; Ice Cores; Isotopes; Little Ice Age; O-18/O-16; Oxygen; Paleoclimatology; RatiosOne of the most salient features in the last millennium of climate history is the Little Ice Age, a loosely-defined period of cold temperatures and increased climatic variability that has been documented in many parts of the globe. As this figure shows, the Little Ice Age is identified in the Quelccaya climate record as a period of colder (more negative) oxygen isotope ratio roughly bracketed between 1550 A.D. and 1900 A.D. The accumulation record is more complex, showing a pronounced wet period before 1700 followed by significantly drier conditions thereafter.
PhotographerLocation
NOAA

Credit Line: Courtesy National Oceanic and Atmospheric Administration
South America; Peru; Altiplano; Quelccaya Ice Cap
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32jsbSubject: VolcanoesDescription
Active Volcanoes; Cascade Range; Explosive Eruptions; Geologic Hazards; Lakes; Stratovolcanoes; Volcanic Debris; Volcanic Effects; Volcanism; VolcanologySpirit Lake, once surrounded by lush forest, is within the area devastated by the blast of Mt. St. Helens on May 18, 1980. Remnants of the forest now float on the surface of the lake. Another Cascade Volcano, Mt. Rainier (14410 feet), is in the distance. The view is from the south.
PhotographerLocation
Lyn Topinka

Credit Line: Courtesy USGS Cascade Volcano Observatory
North America; United States; Washington; Mount Saint Helens
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32k8qSubject: MineralsDescription
Blue Lead; Isometric; Lead Ores; Lead Sulfide; Mineralogy; SulfidesGalena sample.
PhotographerLocation
USGS

Credit Line: Courtesy United States Geological Survey
North America
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32kgvSubject: MineralsDescription
Blue Lead; Isometric; Lead Ores; Lead Sulfide; Mineralogy; SulfidesGalena sample.
PhotographerLocation
USGS

Credit Line: Courtesy United States Geological Survey
North America
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32kqqSubject: MineralsDescription
Blue Lead; Isometric; Lead Ores; Lead Sulfide; Mineralogy; SulfidesGalena sample.
PhotographerLocation
USGS

Credit Line: Courtesy United States Geological Survey
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32ky0Subject: MineralsDescription
Isometric; Pseudogalena; Sulfides; Zinc Blende; Zinc Iron Sulfide; Zinc OresSphalerite sample.
PhotographerLocation
USGS

Credit Line: Courtesy United States Geological Survey
North America; United States; Colorado; Commodore Mine
Photo Quality | LargeAvailable for Commercial Use

Photo ID: h32l7eSubject: MineralsDescription
Antimony Sulfide; Hydrothermal Minerals; Mineralogy; Ores; Orthorhombic; SulfidesStibnite sample.
PhotographerLocation
USGS

Credit Line: Courtesy United States Geological Survey
North America
Photo Quality | LargeAvailable for Commercial Use

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