Attention - This cache can only be visited at low tide!
Pseudomorphs
Pseudomorphism by substitution involves the gradual replacement of original material by an unrelated mineral without chemical reaction between the two. Petrified wood is a common example of this class of pseudomorph. At this location you can see some petrified wood, but only at low tide. Before visiting this Earthcache check the tide times.
What is Petrified Wood?
Petrified wood is a fossil. It forms when plant material is buried by sediment and protected from decay due to oxygen and organisms. Then, groundwater rich in dissolved solids flows through the sediment, replacing the original plant material with silica, calcite, pyrite, or another inorganic material such as opal. The result is a fossil of the original woody material that often exhibits preserved details of the bark, wood, and cellular structures.
But in this case, something else happened here.
Taken from the information board:
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Hraunafsteypur
Í fjöruborðinu hafa varðveist merkilegar hraunafsteypur af trjám. Þau hafa hrifist með hraunflaumi sem vall yfir búsvæði þeirra, fyrir meira en 5 milljón árum. Vellandi hraunkvikan hefur umlukið trjábolina og snertifletir storknað á meðan trén brunnu innan í. Við það mynduðust holrúm eða mót, sem féllu ekki saman. Kvikan utan við var enn nógu heit til þess að troðast inn í holrúmin á eftir og mynda afsteypur. Kvikan kældist hratt við snertifleti mótanna og glerjaðist en innan við það varð storknunin hægari og bergið því grófara. Geislamynstur inn að miðju afsteypanna sýna kælingu umhverfis afsteypuna storknun verður hornrétt á kæliflöt.
Afsteypurnar eru í flæðarmálinu og sjást einungis á fjöru. Þetta eru viðkvæmar og sérstæðar jarðminjar sem verður að umgangast af virðingu og sem ekki má skemma.
Náttúrustofa Suðausturland
Pseudomorphs
At the tidemark a remarkable pseudomorphs of trees are preserved. They formed when a molten magma flow eradicated trees from their habitat ground more than 5 million years ago. The molten lava enveloped the tree trunks, solidifying at the contacting surface, while the tree burned inside. A cavity, or a mould, was formed without collapsing. On the outside the magma was still hot enough to penetrate into the mould and forming a pseudomorph. At the contacting surface inside the mould a rapid solidification resulted as a glass but inside it the cooling rate was slower and a coarser rock formed. The radial pattern to the center of the pseudomorphs, demonstrates how the cooling is perpendicular to the contact surface.
They are located at the tideline and can therefore only be observed during low tide. These are very fragile and unique relics and must be respected to prevent the pseudomorphs from being damaged.
South East Iceland Nature Research Center
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To log this Earthcache as a found, send me the answers of the following questions via Message Center or E-Mail.
1) Tell me the average diameter of the petrified wood you found here.
2) Explain in your own words how this petrification happened.
3) Post a picture with you, your GPS, or personal item at the given coordinates. Please don't post pics with the wood! These photos will be deleted!