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Graffiti (singular graffiti or graffito, the latter only used in graffiti archeology) is writing or drawings made on a wall or other surface, usually without permission and within public view. [ 1 ] [ 2 ] Graffiti ranges from simple written "monikers" to elaborate wall paintings, and has existed since ancient times , with examples dating back ...
Significant early cave paintings, executed in ochre, have been found in Kimberley and Kakadu, Australia. Ochre is not an organic material , so carbon dating of these pictures is often impossible. The oldest so far dated at 17,300 years is an ochre painting of a kangaroo in the Kimberley region, which was dated by carbon dating wasp nest ...
Diver looking at a shipwreck in the Caribbean Sea. Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. [1] The name scuba is an anacronym for "Self-Contained Underwater Breathing Apparatus" and was ...
Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale -type sedimentary rock composed of clay or volcanic ash through low-grade, regional metamorphism. It is the finest-grained foliated metamorphic rock. [1] Foliation may not correspond to the original sedimentary layering, but instead is in planes ...
The paradox is this: with the young Sun's output at only 70 percent of its current output, early Earth would be expected to be completely frozen, but early Earth seems to have had liquid water [2] and supported life. [3] The issue was raised by astronomers Carl Sagan and George Mullen in 1972. [4] Proposed resolutions of this paradox have taken ...
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, [ 1 ] although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the ...
Meteoroid. A meteoroid shown entering the atmosphere, causing a visible meteor and hitting the Earth's surface, becoming a meteorite. A meteoroid (/ ˈmiːtiərɔɪd / MEE-tee-ə-royd) [1] is a small rocky or metallic body in outer space. Meteoroids are distinguished as objects significantly smaller than asteroids, ranging in size from grains ...
The coloring of the Atlantic spotted dolphin varies enormously as it grows, and is usually classified into age-dependent phases known as two-tone, speckled, mottled, and fused. Calves are a fairly uniform gray-white, with one or no spots. When they are weaned, speckling occurs, typically between 3 and 4 years and lasting for an average of 5 years.