Kousky z minulosti / Fragments from the past EarthCache
Kousky z minulosti / Fragments from the past
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Od 1. 7. 2014 menim pravidla pro zasilani odpovedi na otazky. Od ted musi byt odpovedi doruceny do 24 hodin od zalogovani found it. Navic kazdy nick odesle sve odpovedi za sebe. Bude-li nekdo odesilat odpovedi za vice nicku, bude log uznan jen jemu a zbytku budou logy smazany. Mazat logy budu bez varovani, varovani jste v listingu. Dekuji.
Tato jednoducha earthkes Vas zavede do prazske botanicke zahrady, kde krome rozlicnych druhu rostlin naleznete i zkamenele fragmenty dřeva z davne historie Zeme.
This easy earthcache will bring you to Prague botanical garden where you can see not only different kinds of plants but also petrified fragments of wood from ancient history of the Earth.
Od 1. dubna do 31. rijna je nutne zaplatit vstupne 50 Kc, v ostatní mesice je vstup zdarma. Pro děti, studenty, seniory a rodiny jsou slevy.
There is small access fee to botanical garden (50 Kc) since April 1st till October 31st, other months the access is free. There is also discount for children, students, seniors and families.
ZKAMENELE DREVO
Zkamenele drevo je specialni typ zkamenelin suchozemskych rostlin. Jedna se o vysledek petrifikace (zkameneni) stromu. Behem tohoto procesu jsou vsechny organicke materialy premeneny na mineraly. Aby mohl proces petrifikace probehnout, musi byt drevo v prostredi bez pristupu vzduchu, aby nedochazelo k rozkladnym procesum. K tomu docházi pohrbenim dreva pod nanosy vulkanickeho popela, bahna nebo pisku.
Proces petrifikace muzeme rozdelit do dvou zakladnich kroku:
1) Pote, co je drevo pohrbeno pod nanosy popela nebo bahna a zaroven je pritomna voda nasycena mineralnimi latkami, dochazi k postupnemu vyplnovani prazdnych dutin a bunecnych prostor (lumen) roztokem mineralu, ktere postupne krystalizuji. V tomto kroku zustava zachovana bunecna stena. Tomuto procesu se rika permineralizace
2) Ve druhem kroku dochazi k rozkladu a rozpusteni bunecnych sten. Prostor po bunecne stene je nasledne vyplnen roztokem mineralu, ktere pozvolna opet krystalizuji a nahrazuji tak bunecnou stenu. Cim pomalejsi je tento proces, tim detalneji je zachovana struktura puvodniho dreva.
- Puvodni struktura dreva.
- Bunecny prostor je nahrazen krystaly mineralu, bunecna stena zustava.
- Bunecna stena je rozlozena a odstranena.
- Prostor po bunecne stene je nahrazen mineraly.
PERMINERALIZACE
Jak uz bylo uvedeno, jedna se o nahrazeni organickeho materialu mineraly. Podle prevahy urciteho mineralu rozlisujeme permineralizaci na:
- SILICIFIKACE - zakladni slozkou je oxid kremicity
- KALCIFIKACE - zakladni slozkou je uhlicitan vapenaty
- PYRITIZACE - zakladni slozkou je pyrit (FeS2)
V pripade zkameneleho dreva je nejvyznamejsi silicifikace.
Na miste, na kterem se prave nachazite, muzete videt krasne priklady zkameneleho dreva ruzne zabarveneho.
Ted uz ale k samotnym otazkam (odpovedi mi poslete pres profil):
- Jak se spravne nazyvaji zkameneliny z obdobi prvohor, ktere se tu vyskytuji? (NEJSOU TO ARAUKARITY!!!)
- Z jakeho obdobi prvohor je zde nejstarsi zkamenele drevo? Uvedte nazev obdobi i priblizne stari.
- Odkud sem byly dovezeny zkameneliny z obdobi miocenu?
- Na jednom zkamenelem dřevu muzete videt syte rude zabarveni jednoho mineralu na bazi oxidu kremiciteho. O jaky mineral se jedna? (viz spoiler) Popremyslejte a prostudujte internet. V zadnem pripade ale netipujte.
Dobrovolne muzete k logu pripojit i fotku z tohoto mista. Po odeslani odpovedi muzete logovat. Ozvu se, bude-li neco spatne, zejmena pri spatne odpovedi na 4. otazku.
ENGLISH VERSION:
PETRIFIED WOOD
It is special type of fossilized remains of terrestrial vegetation. It is the result of petrification of a tree. During this process all organic materials are replaced with minerals. The process of petrification can run only if the wood is in an environment free of air to avoid decomposition processes. This happens when wood is buried beneath the volcanic ash, mud or sand.
Petrification process can be divided into two main steps:
1) After the wood is buried under layers of ash or mud empty cavities and cellular space (lumen) are gradually filled with water solution of minerals that crystallize. In this step, the cell wall remains intact. This process is called permineralization.
2) The second step is the decomposition and dissolution of the cell walls. The empty space is then filled with a solution of minerals that crystallize slowly again and replace the cell wall. The slower the process is, the more detailed the original structure of wood is.
- Original structure of wood.
- Cellular space is replaced with crystals of minerals, cell wall remains.
- Cell wall is decomposed and removed.
- The space after the cell wall is replaced by minerals.
PERMINERALIZATION
As already mentioned, it is the replacement of the organic material with minerals. According to the predominance of certain mineral the permineralization can be divided into:
- SILICIFICATION - main component is silica
- CALCIFICATION - main component is calcite
- PYRITIZATION - main component is pyrite (FeS2)
In the case of petrified wood the most significant process is silicification.
In the place where you are, you can see beautiful examples of petrified wood variously colored.
Now, to your task. Send me answers to these questions via my profile:
- What is the right name of petrified wood from the Paleozoic Era, which you can see here?
- From which Paleozoic period is the oldest petrified wood here? Provide the name of this period and approximate age.
- From where were the miocene fossils brought here?
- On one petrified wood you can see deep red color of one silica-based mineral. What is its name? (see spoiler)
Optionally, you can upload picture from this location. After sending your answers you can log immediately. I will contact you if there is any problem.
zdroj/source:
http://en.wikipedia.org/wiki/Petrifaction
http://www.geocities.ws/peforanger/palette.html
Additional Hints
(Decrypt)
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