What Color is the Earth? A black crust

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Focus on VisionColor from oxygenThe palette of broadly distributed yellow,red and brown tones on thegray-black continents came intobeing only after free oxygen had formedin the original atmosphere. Atthe time, the earth presumably alreadyhad more than half of its life spanbehind it. Rain water is another significantfactor in the appearance of colors.It decomposes the dark silicateminerals containing iron, releasingthe iron which combines with oxygen.This process results in yellowcoloredand red-colored iron oxides.Like so many obscure details aboutthe enrichment of the earth's atmospherewith oxygen, it is still unclearwhy it took more than one and a halfbillion years for sufficient oxygen tobecome available in the atmosphereto form compounds with iron. Red,yellow and brown in many shadesare the colors of weathering. In mostcases, brown is nothing more thanrust and can occur in all climates onearth.Fig. 3:Till pyramids near Bozen,Italy.Rain water has sculptedslim cones out of the mix ofsand, clay and stonesdeposited by glaciers manytens of thousands of yearsago. The formations whichare up to 15 m high arecolored bright red by veryfinely distributed ferrousoxides.Blue primeval oceanFig. 2:Great Bahama bank nearthe island of Eleuthera.The seabed between theislands and reefs of theBahamas lies only justbelow the water level. Thelocal inhabitants of theislands gage the depth of thewater from its color: up to adepth of 10 m, the sea is agreenish to turquoise color,while deeper water has ablue shimmer. Currentshave driven the sand togetherinto dunes (aerialphotograph).The steam issuing forth from the cratersin the young earth's surfaceamassed to form clouds, resulting intorrential rain. The precipitationcollected in valleys, forming lakes andoceans. Or might water have originatedon earth as the result of the impactof comets or lumps of ice hurtlingthrough space? Another colorwas added to the black-gray rockcrust: the blue of the oceans. Blue isthe color of the oceans and thus theearth's main color. However, theoceans, lakes and rivers really onlyshimmer in unadulterated blue onlywhen scarcely any suspension particlescloud the water.6Innovation 9, Carl Zeiss, 2001Innovation 9, Carl Zeiss, 2001 7
Focus on VisionFig. 4:Salt lake in Death Valley,California, USA.In the hot desert sun, thewhite crust of the salt lakebursts into countlesspolygons of one to threemeters diameter. Along thedry cracks, moisture seepsfrom the muddyunderground, causing theedges of these polygons toarch. Salt particlescrystallizing out of theevaporating water pile uphere.Green landSince primeval times, the color whitehas been present on our planet in theform of glaciers. The first traces oficing in the earth's history are 2 billionyears old. However, at least temporarily,other large white areas existedon earth. Some very flat oceanbasins were located in such a hot andWhite created by ice and saltdry climate that the water completelyevaporated several times, depositinglight layers of salt.Billions of years had to pass beforethe color green conquered the continents.This color appeared approximately420 million years ago afterbacteria produced oxygen for thefirst time in the primeval oceans. Thepioneers among the plants that venturedout of the water on to the landwere stalky marsh growths. However,it took another 50 million years forthe plants to form supporting stems,supply vessels and roots. Only thendid vegetation spread over the continentsto color the landscapes green.The plants' panoply of green givesthe planet more than color: it alsoreinforces and protects subterraneanearth levels. However, not only landbut also rivers, lakes and shallow seasare green when they contain microscopicallysmall algae which floatabout in the water, with the intensityof the water color increasing in relationto the density of the algae.Fig. 5:Crater of the 2,890 m highOl Doinyo Lengai inTanzania, Africa.Only during the rainyseason are the flanks of thisvolcano green up to thecrater's edge. The lava thatoccasionally flows from thesharp cones in the crater isunique. Reaching atemperature of only 550 °C,the lava contains largeamounts of sodium andpotassium, and itsemissions are black, unlikethe usual run of volcanoeswith their red-hottemperatures of over 1,000degrees centigrade. Aftercooling, the lava turns whitewithin a few days (aerialphotograph).The photos and theslightly revisedcommentary have beentaken from thephotographic art book“Nature's Studio. ColorStudies” by BernhardEdmaier (photos) andAngelika Jung-Hüttl (text),BLV VerlagsgesellschaftmbH, Munich.The photos were takenwith Hasselblad 201Fcameras and Flexbodywith the following lensesfrom Carl Zeiss:40 mm Distagon ® f/4 FLE,50 mm Distagon ® f/4 FLE,60 mm Distagon ® f/3.5,80 mm Planar f/2.8,100 mm Planar ® f/3.5,120 mm Makro-Planar ® f/4,150 mm Sonnar ® f/4,250 mm Tele-Tessar ® FE f/4,250 mm Sonnar ®Superachromat f/5.6.All photos were takenwithout color filters.The reproductions are trueto nature, using no formof electronic picturemanipulation. Furtherinformation and photos atwww.geophot.de.8Innovation 9, Carl Zeiss, 2001Innovation 9, Carl Zeiss, 2001 9
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What Color is the Earth? A black crust

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