[.................At present the wonders of sand will be presented via text only. Later, I will download photos of sandy beaches, desert sands, etc............................................................]
SANDS OF TIME
"Sand," Rachel Carson tells us, "is a substance that is beautiful, mysterious, and infinitely variable, each grain on a beach is the result of processes that go back into the shadowy beginnings of life, or the earth itself." There is nothing particularly striking about a grain of sand, unless, of course, you have the misfortune of having one blow into your eye. Then the speck that seems so benign and innocuous reveals its true character as a descendant of the great rocks of the world.
But to sedimentologists, geologists, and paleogeographers, the size, shape, roundness, surface texture, and composition of a single grain of sand tell the story of forces that pried it from its matrix and brought it to the shore. If one sifts through a handful of sand, and looks closely at the grains, it is possible to detect many individual shapes, sizes, and colors; these variations are even more dramatic if samples come from different beaches. Some grains are almost perfectly round and smooth, others jagged, rough, and irregular in texture and shape. Light-colored, nearly spherical sand is composed almost entirely of quartz, a common mineral from which the earth's crust is compounded. In contrast, dark sands are made up of volcanic particles and complex silicates that were spewed up from deep within the earth's core.
Nearly indestructible, a single grain of sand can be millions of years old. These fragments can be seen as the original "silicon chip," acid-etched with the story of the rise and fall of mountains, rivers, deserts, and creatures. Lilliputian messengers from the depths of geologic time, grains of sand are the bridge between past and present--the last, hardy survivors of distant islands, deltas, cliffs, mountains, and long-lost landforms. Buffeted by wind, leached by rain, bleached bone-dry by the sun, sands are also made up of the carbonate skeletons of creatures from the tepid tropical seas, and in this respect are geological cartes de visite from obscure worlds beneath the waves.
Generally ranging in size from one sixteenth of a millimeter to two millimeters--and sometimes even five millimeters--in diameter, sand is smaller than gravel but larger than silt or clay. The rich tonal variations and range of shapes emerge fully only under a microscope, where sands reveal themselves as pointed and bulbous rays exploding from pillow-shaped centers; creamy lozenges; shiny ball bearings; jagged, striated, and pitted flakes; glossy disks and striped cigars; spheres as bumpy as Trix cereal; shriveled red chiles of volcanic lavas; and crystalline green jelly beans bursting with glauconite from the ocean floor.
The mechanics of sand formation are simple. Rocks, reefs, and coral break down through either mechanical or chemical weathering, becoming smaller and smaller as they are pounded by the hydraulic or pneumatic pressure of waves. They are pried apart by ice exerting thousands of pounds of pressure per square inch, or split by the insistent probing and prying of plant roots. Heated by lightning or fire, rocks expand until they break off in chips and flakes. Or, through involved chemical processes, minerals and chemicals within the rocks-gradually decompose, and the rock literally decays as if it were an organic substance. The size of each resulting grain is determined by the kinetic intensity of the medium that transported and deposited it. A strong current or a powerful wind, for instance, tends to carry larger particles greater distances. The smoothness or the jaggedness depends on the degree of abrasion during transport. The rounder the sand, the longer it has been weathered by wind or water. By contrast, ragged grains have either not traveled far or been cushioned in their journey by an envelope of mud.
The weathering process that turns rocks into sand, however, is only half the story. The other half involves the consolidation of sands into rock during the vast intervals of geological time. The rock of ages, as it turns out, is impervious to time only in our minds. Sand that once was rock becomes rock once again as it slowly sediments and compresses into layers of sandstone, which, in turn, transmute into sand. Standing on a cliff overlooking a raging sea, we watch waves hurl themselves against the shore, scooping up cobbles at the base of the cliff and lofting them into the crown of seething foam. Then the wave retreats, hauling its load of stone along the sea bottom, until the next swell rushes in to repeat, relentlessly, the work of breaking, grinding, polishing.
In warm waters, abundant sea life provides a steady source of bone and shell fragments, from conches, clams, mussels, scallops, shellfish, corals, fish, and even microscopic plankton. Most of the fabled white beaches of the world are in fact the burial mounds of such sea life. Radiocarbon dating shows that the sand of Miami Beach, for example, is on average thirteen thousand years old, with some material over thirty thousand years old. So, as we dig our toes into the soft shell sands, we quite literally burrow deep into antiquity.
Because sand is derived from a spectrum of substances, it comes in many colors--tan, yellow, white, pink, purple, red, blue, green, gray, and black. The precise shade of each grain depends on the rock or organism from which it came. To a great degree, color alone can identify the origin of a beach with reasonable accuracy. Armed with a strong hand-lens, an experienced geologist can readily distinguish between translucent, light-colored grains of quartz and brown, dullish feldspar, and then link these properties to the geological history of a specific beach type.
Delivered to their site long ago by slowly moving glaciers, the whitish beach sands of the Northeastern United States are mainly mineral in origin. As one moves farther south--to North Carolina, let's say--the sand begins to take on the pinkish and pale-yellow hues of crushed seashells. Florida's eastern flank is rimmed with coarse grains of quartz, but the tip and the western shore are covered with sand the color and feel of uncooked semolina. Along the Gulf Coast, the fine-textured beaches blend the rosaceous tint of pulverized shrimp and conch with the white, yellow, and orange colors of minerals--copper, calcium, and quartz--carried there by rivers from the Appalachian highlands and the Great Plains.
As one moves farther south and west, beach sands begin to broadcast a flashy, south-of-the-border exuberance characterized by the paintbox tints of tropical seas. The brilliant white of Bahamian beaches is derived from the precipitated oolites or calcium-carbonate coating on bits of coral and whelk. Bermuda's pink sands blush with the calcite of limestone, coral, and shell. The gray sands of St. Lucia's southwestern rim, on St. Kitts, Saba, and Domenica--all in the Caribbean--bespeak a volcanic origin. In fact, the mixture of vanilla-colored shell and coral beaches and dusky volcanic sands is a formula repeated throughout the tropics. This pangeological recipe is evident in the golden coral beaches of the Seychelles in the Indian Ocean, the mauve-and-purple sands of Fiji's Taveuni Island, and in Queensland's kaleidoscopic blends of ground-up shells from the Coral Sea. The striking hues of Hawaii's shores--the olivine green of Papa-kolea Beach, the cinder-cone red at Hoku-'ula, and the jet black of Polulu Beach--also derive from volcanic eruptions, rather than decomposing sea life.
As one travels north into the temperate zone, the color palette of beach sand fades in vibrancy. On the eastern coast of England, the pockets of sand deposited among the shingle are, like the rock from which they have eroded, light gray. By contrast, the northern coast takes on an almost honeyed hue. Along the northeastern coast of Wales, the golden beaches have a faintly rosy cast. All along the Baltic, the dunes and berms are a soft tan. Mediterranean beaches--the Costas del Sol, Calida, Blanca, Dorada and Brava, as well as the strands on deltas of the rivers Rhone, Arno, Po, and Brenta--range from puce to whitish gray, reflecting the tints of clay, mud, and river sand transported from deep inland. Up and down the Cote d'Azur, along Italy's southern coast, and on the shores of Alexandria, the pale sand flashes an occasional grain of marble, glass, or alabaster that centuries ago was part of some ancient Roman villa. By and large, the meager sands of Mallorca, Sicily, Sardinia, Corsica, and Cyprus--and of other islands in the Adriatic and the Aegean--are coarse, lacking the sustained buffeting of rough winds and waters.
Along the Sea of Cortes and on the Pacific coast of Baja California, the beaches still sparkle with coarse-grained sand colored the buff of desert rock, the white of marlin bones, and the burnt sienna of weathered coral. But along the beaches of the Pacific Northwest, tan and gray predominate. Descended from basalt cliffs that were extruded as sea-floor lavas several million years ago, these sands glisten like oil slicks when wet. The brownish specks scattered among them come from the quartz and feldspar of granites that were spot-welded to the Rocky Mountains of the North American continent, and then spilled down the tributaries of the Columbia River, before draining into the Pacific. Other mighty rivers--the Orinoco, the Amazon, and Argentina's Colorado--enrich ocean sands with grains of gold, platinum, and uranium, to which is added the glint of garnets and emeralds.
In certain beaches, sand exhibits another remarkable property, neither useful nor threatening, but aesthetic. These sands "sing" and "bark," as though they were endowed with vocal cords, although in this instance the musical sounds are produced by the gentle friction of grain against grain. In Kauai, Hawaii, a golden knot of windblown dunes in the shadow of the opal-tinted cliffs of Polihale produce cries in various cadences. In the wind, they rustle like silk; when someone slides down them, they bark like dogs.
Still intriguing scientists, singing sands have been threading through the literature of explorers and travelers for over a thousand years, posing the riddle of their vocalization. Some say the sound is produced by the friction of sand against sand that has been coated with dried salt, much as the violin's melody is produced by the action of resin on the bow. Others speculate that the thin layers of gas which are released between the grains act as percussive cushions capable of considerable vibration and tone production.
Balefully sibilant "singing sands" have been discovered in England and Wales. On the Isle of Eigg, in the Hebrides, the snowy sand at the base of sandstone cliffs gives off an eerie whining. The sands of Oregon's Florence Beach squeak with the high-pitched bark of distant chihuahas. But perhaps the most fabled of these are commemorated in the Arabian Nights, which lauds the weird beauty of the sands skirting the Mountain of the Bell, the Jebel Nagous of the Isthmus of Suez. When whipped up by storm winds, these sands chant and groan like deep organ notes; on calm days, they tinkle like bells.
(C) 1998 Lena Lencek and Gideon Bosker All rights reserved. ISBN: 0-670-88095-7
|Location:||Mallorca. 1.5km South of Porto Cristo, East coast. (39°32'N6.15", 3°19'51.53"E)|
|Classification:||Karst cave. (see post below, Within Her Secret Depths...)|
|Dimension:||T=20°C, H=80%. Subterranean lake: L=177m, W=30m, D=9m.|
|Address:||Cuevas del Drach, Carretera Cuevas, E-07680 Porto Christo, Mallorca, Tel: +34-971-820753, Fax: +34-971-815089. E-mail:|
|1338||first written notice of the cave, in a message of Roger de Rovenach, Governor of the island, to the mayor of Manacor.|
|1632||first appearance of the name "drach" in the book "History of the Kingdom Mallorca" by Demeto.|
|1778||mentioned in Berard y Solà: A Journey through the Internal Mallorca.|
|1784||included into the Mallorca map of Cardinal Despuig.|
|1878||cave visited by two tourists from Barcelona.|
|1880||first map of the cave drawn by the German cartographer a speleologist M. F. Will, published in Munich.|
|1881||second edition of Will's map published in Palma.|
|1895||mentioned in the book Clovis Dartentor by Jules Verne.|
|1896||exploration by E. A. Martel, discovery of the Cueca de los Franceses.|
|17-JUN-1922||cave bought by Don Juan Severa and his wife Angela Amer Nadal. They immediately start the development of the caves.|
|1925||the trails are completed.|
|1929||new entrance tunnel dug.|
|23-APR-1935||the electric light, made by Carlos Buigas, was inaugurated. Buigas was so happy with this work, that he refused to accept any payment for 5 months of work!|
|1950||light redone by Buigas.|
|1951||archaeologic excavation revealed arabic caramics (3000 years old), Bronze Age, Punic, and Roman remains.|
Cuevas del Drach is the most famous and best visited cave on Mallorca. The reasons are probably its outstanding features, like the wealth of speleothems and the impressive underground lake. It may also be a result of very good marketing, but the cave is really worth a visit. There are numerous stalactites and stalamites of pure white colour. At some parts of the ceiling, the stalactites are covered by helictites, on others there are fragile soda straws.
The cave visits are scheduled hourly, visitors walk on their own into the cave. The tour is more than two kilometers long, so there is not very much time to reach the Lago Martel. The chamber of the lake is equipped with seats for about 1,000 visitors, who listen here to short concert with classical music. There is also the possibility to make a boat ride, but this is voluntary.
The concert is held by some musicians on three boats, who glide silently into the lake to play their lake concert. They play Alborada qualleqa by Caballero, Plaisir d'amour by Martini, Tristesse, study 3 opus 10, by Frederik Chopin, and Barcarola from Hoffman's Tales by Jaques Offenbach. The music is available on CD.
It seems, the opinions about this cave differ very much, they are controversial. Many people regret that there is not enough time to enjoy the cave and its speleothems, others think the concert is kitschy. At the end everybody has to make up his own opinion. To avoid the crowded times, it is probably a good idea to take the first or last tour, or visit the cave during the winter.
The name Cuevas del Drach is, of course, derived from the dragon. The first inhabitants of Mallorca gave the dragon rather different attributes: on one hand, he is evil, a sort of devil, on the other hand he is a symbol for strength. This second aspect was definitely the reason, why King Jaime I is shown on the medieval paintings of Francesc Comes and Pere Nisart with the dragon on his helmet. In the medieval legends, in the Rondaies mallorquines, the most important collection of mallorcan fairy tales, the dragon has a third aspect: he is the sentinel of a treasure. With his horrible looks, snake like body and bat like wings, and his enormous strength, he defends the treasure against intruders.
The cave was visited during centuries, an example is a cave visit by two tourists from Barcelona in 1878. They astrayed, although they had a local guide, and they nearly died of starvation in the cave.
The most famous name in the history of the cave is E.A. Martel. He arrived early September 1896, after an invitation of Archduke Ludwig Salvator, who lived in Miramar. On the 9th September he entered the cave the first time. Until then three chambers where already known: Cueva Negra (Black Cave), Cueva Blanca (White Cave) and Cueva Luis Salvator. At the end of this third chamber was a place called La ventana (the window) where terra inkognita started.
La ventana allowed a view on an enormous lake. Martell used his new developed gear, which were in fact two boats, to cross this lake, which is today called Lago Martel (Lake Martel) to his honor. He was rather impressed by this silent boat tour on one of the world's largest subterranean lakes, 177m long and 30m wide. Lago Martel has a temperature of 17°C and is a little salty, which proofs a subterranean connection to the Mediterranean Sea. Behind the lake he discovered a new part of the cave, today called Cueva de los Franceses (Cave of the French), also to his honor.
The members of this expedition where Martell, his companion Luis Armand, Fernando Moragues, son of the cave owner, and Pedro Bonel de los Herreros, grandson of Ludwig Salvator's steward.
|Main Index Spain Mallorca|
Stone Forest (Shilin) http://www.terragalleria.com/asia/china/shilin/shilin.all.html
Marvelous slide show of caverns. Indian Echo Cavern, Hummelstown,Pa.;Wyandette Caverns, Leavenworth, In.; Caverns of Sonora, Sonora, Texas.
Click on "gallery" in header to access photos. Click on small photos to view enlargements. Click on arrows to advance to next set of photos.
Labels: volcanoes-national park/monument
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