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  Terrestrial globes as the one above left are used to present the physical features of the earth in proportion.
It was made by Johannes Praetorius, in 1568, and shows Europe, Asia, and Africa, as well as the recently discovered Americas.
Celestial globes, as the one on the right, show the relative positions of astronomical features of the heavens, such as stars and constellations as seen from earth. Globes have been produced since the time of the Pythagoreans. They became more important when on voyages of discovery more distant lands beyond the familiar Mediterranian were found. and accurate maps were urgently needed. The earliest extant globe was made by Martin Behaim of Nürnberg in 1492, the year Columbus discovered America, which of course is not yet shown on it.
 Germany and Flanders were centers of globe manufacture, and particularly distinguished was Gerhardus Mercator (1512-1594), a Flemish geographer who broke away from the Ptolemaean stranglehold on cartography in the late Middle Ages. Venerated maps with centuries-old misinformation were found to be increasingly inconsistent with the recent observations of mariners. His solution to the problem of distortion of physical features on the sphere of the earth when projected onto a flat map was the cylindrical, or Mercator, projection still in use today. The Belgian stamp on left shows Mercator holding his famous globe.
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Old maps show the coast of North America and Iceland, country of issue. |
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 This U.S. Bicentennial stamp shows Benjamin Franklin
(1706-90) with an early map of North America, though not one of his own.
Franklin published maps of the newly founded United States and he also
mapped the currents of the gulf stream during his frequent crossings to
Europe. Great Britian honored Franklin on the occasion of the American Bicenteninial in 1976. |
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Christopher Hansteen (1784-1873), a native of Norway, was a physicist
and astronomer who devoted his time to the study of geomagnetism. In 1701
Halley had already published a map of magnetic declinations, and the subject
was studied by Humboldt, de Borda, and Gay-Lussac, among others. Hansteen
collected available data and also mounted an expedition to Siberia, where
he took many measurements for an atlas of magnetic strength and declination.
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Friedrich Wilhelm Heinrich Alexander von Humboldt (1769-1859) explored many parts of the earth, including the Americas; the cold current off the west coast of South America bears his name. He was a geologist, naturalist and collector of specimens who wrote an encyclopedic work in geology and geography, Kosmos. |
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cP This interesting stamp was issued by the DDR in 1980 as part of a set of four dealing with geophysics and the methods used to explore various properties of the earth. A seismograph is used to measure vibrations in the earth, or earthquakes. Here is a diagram of the concentric layers of the earth, the main ones being the core, the mantle, and the crust. The relatively thin crust is composed of rocks like granite and basalt, while the mantle contains much denser mineral rocks. The lithosphere comprises the crust and the upper part of the mantle and is divided into the tectonic plates which move around on the astenosphere. It includes much of the upper mantle, and while not liquid, deforms by plastic flow. Between the crust and the mantle there exists a boundary known as the Mohorovicic discontinuity, or Moho. Here P (compressional) waves are propagated at a much higher rate than in the crust above. The Moho lies from 5 km under the oceanic ridges to 75 km under the continents. The inner core is 1220 km thick and composed of solid iron; the outer core is nearly twice as thick (2220 km) and is liquid iron |
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Alfred Wegener (1880-1930), a German geologist and arctic explorer, advanced
a theory of continental drift where the lighter continents are floating
on denser underlying material in the earth's crust. What was a single
landmass, the supercontinent Pangaea, supposedly broke up into our present
continents, which then drifted apart, as shown on the Berlin stamp on
the right. Wegener noticed how the the shapes of Brazil and Africa fit
together. The existence of a landbridge in the past would account for
the paleontological similarities discovered between the two continents.
Wegener disappeared on his fiftieth birthday while on an meteorological
expedition in Greenland. |
| Since Wegener's time, much research has led to a detailed picture of the movements of continents and their plates in the 4.6 billion years of the earth's history. In time, the global crust formed supercontinents which thousands of millions of years later broke up again into smaller sections that moved apart. The latest supercontinent Pangaea, was composed of a northern part Laurasia (made up of present-day North America, Europe, and Asia) and a southern part Gondwana, which was incidentally formed 500-700 MYA (million years ago) after the breakup of an earlier supercontinent, Rodinia. Laurasia broke away from Pangaea about 150 MYA, leaving Gondwana (incorporating Africa, Antarctica, Australia, India, and South America), which also began to disintegrate. The set of stamps from British Antarctic Territory issued in 1982 deals with the continental drift of Gondwana and its resulting parts, as seen from the vantage point of Antarctica and the South Pole. It also documents the climatic changes that have taken place in Antarctica as revealed by fossils of trees, shrubs, and animals. Shown is lystrosaurus. What was a tightly packed assembly 280 MYA (#1) had moved north en masse by 175 MYA (#3), when violent volcanic activity also occurred. The continents were seen widely dispersed 50 MYA (#5), Africa and South America opening a wide rift 100 million years ago and moving north while Australia was still closely bound to Antarctica. In the upper right quadrant India, a triangle, can be seen heading for Asia to form the Himalayas. The last stamp (#6) shows the present alignment of the continents around Antarctica, and penguins as its current population. |
 
 
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A fault results from fracturing and differential movements of layers along fractures in the earth's crust. This Canadian stamp shows a normal dip-slip fault. |
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When molten rock flows into a fissure of existing rock strata and later
solidifies, it is called a dike. This stamp from the Aland Islands shows
a diabase (dark-colored intrusive igneous rock, a coarse basalt) dike
in Sottunga. Dikes can be short or many miles long. Another interesting
stamp from this set shows a formation of pillow lava, which is considered
to be the result of underwater extrusion. |
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This Russian stamp of geological exploration has it all - underground explosion, airplane, truck, derrick, reflections of waves from different layers. This is what makes science stamps, and indeed many other stamps, so much fun: they tell a story of a process, an event, they are instructive. |
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 In 1908 a major interaction between earth and an
asteroid or meteor occurred over Siberia, then, as now, sparsely populated.
Thousands of acres of pine forest were devastated and went up in flames,
dust in the upper atmosphere colored sunsets, but outside of Siberia the
cause of these signs remained unknown and was supposed to be an earthquake.
In 1927 the Russian scientist Leonid Kulik mounted an expedition to the
remote Tunguska area and found the blast site. The explosion is estimated
to have had the force of 40 megatons of TNT, and the effects on the landscape
are still visible today. Since there is no impact crater, the explosion
likely took place some seven kilometers above ground. Another meteor fall over eastern Siberia in the Sikhote-Aline mountains in 1947 was witnessed by people on the ground at distances of 300-400 km. The meteor was seen as a fireball that exploded. The impact could be felt for 100 miles and the many fragments created 24 major and 98 minor craters. The weight of the material (iron) is estimated at 70 to 100 tons. The Russian painter P.L. Medvedev observed this spectacular event and painted it from memory, as shown on the stamp at right . |
| Like many solitary groups of islands, the Tristan da Cunha islands are of volcanic origin, periodically fated to revisit their creation. Located south of the equator in the South Atlantic Ocean, the roughly circular main island houses the only settlement in the shadow of the volcano. One source of income of the islanders is the sale of postage stamps, and this colorful set provides vivid images of the volcanic activity that most recently in 1961 forced the evacuation of the entire population of 300 to England, half a world away. The first stamp shows the formation of a volcanic island rising up from the sea and the hot magma erupting in a lava flow. Cinder cones are formed by volcanic debris accumulating around vents. |
 
 
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| A more recent example of the birth of an island is the creation of the island Surtsey. From 1963 to 1967, this volcanic island erupted from the sea floor south of Iceland, and as it rose to the surface, violent interactions between hot magma and cold water occurred, a process that is now called surtseying. The contemporary Icelandic stamps below show the island in the making, obviously a spectacular series of events. Volcanoes around Iceland are nothing new; accounts of St Brendan's sixth century voyage from Ireland to North America include descriptions of volcanic activity which threatened the seafaring monks, as shown on the Faroe Islands stamp below. |
 
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| Last Modified: 23 October 2005 mn URL: http://ublib.buffalo.edu/libraries/asl/exhibits/stamps/geol.html Comments to: mnaylor@buffalo.edu Back to: Arts & Sciences Libraries Copyright 1997, 2005 Maiken Naylor |
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