That is why areas of the Park are covered with a litter of petrified wood trunks, branches and fragments. Today, visitors to the park can observe the petrified wood and photograph it; however, collecting petrified wood in the park is prohibited.
Peanut wood: A close-up of a slice of petrified wood from Australia known as "peanut wood" because of its white markings the size and shape of peanuts. The "peanuts" are actually boreholes made in the wood by a shipworm which is a tiny species of clam. If you look closely you can see a spiral-shaped boring that traverses the width of this image second row from the bottom.
Learn more about peanut wood. Petrified wood is not rare. It is found in volcanic deposits and sedimentary rocks at many of locations worldwide. It is sometimes found where volcanic activity covered plant material with ash, mudflows or pyroclastic debris.
It is found where wood in sedimentary deposits was replaced by minerals precipitated from groundwater. It is especially abundant around coal seams, although many of the wood specimens in these locations are casts and molds rather than petrifications. One almost unbelievable material from Western Australia is known as " peanut wood " because of its ovoid markings, but those markings are actually boreholes drilled by a clam! Colorful petrified wood: Petrified wood with spectacular colors and full petrification is highly prized for lapidary work.
It can be polished and used to make jewelry and many other crafts. Opalized Wood: A nice piece of opalized wood from Oregon. It is colorful, accepts a bright polish, and shows excellent wood grain. This specimen measures about 3 inches across. Some of the best specimens of petrified wood have been preserved by silicification. Two forms of silicification are common. The most abundant is wood that has been replaced and infilled by chalcedony sometimes called "agatized wood".
The other form is wood that has been infilled and replaced by opal usually called " opalized wood ". Both of these varieties can be called "silicified wood" if you are not certain of their identity.
These materials can have a similar appearance that requires testing to positively identify. However, if you have experience in geology or gemology, the tests below are very helpful in separating them. Opalized wood has a lower hardness , a lower refractive index, and a lower specific gravity than chalcedony, as shown in the table below. Support this mission by becoming a sustaining member today. Get smart curated videos delivered to your inbox.
Twitter Instagram. Primary Menu. Search for: Search. This area went from deeply buried to being uncovered and raised more than 1 mile above sea level. As a high point, it is continuously eroding away, exposing old rocks and their fossils, such as the petrified logs from the Triassic. So the movement and erosion of the land is what caused the logs to break.
And the inner surfaces where they've broken are flat because quartz doesn't break neatly across its crystal faces, so instead it snaps across the log's shortest area across — sort of like when you snap a piece of chalk, Parker says. When an organism dies, it usually decomposes. Such is the circle of life. The process that most people call " rotting " is a type of decay which sets in as microorganisms break down organic matter.
Usually, a dead, fallen tree will be subjected to this process. Once in a while, though, a newly-deceased tree or some other kind of woody plant gets rapidly buried by mud, silt or volcanic ash. This blanketing material then shields the dead tree from oxygen. Because oxygen is the main driving force behind the decaying process, the smothered plant will begin to decompose far more slowly than it normally would.
Meanwhile, mineral-laden water or mud seeps into the dead tree's pores and other openings. As our plant's internal structure gradually breaks down, its organic material wood fibers gets replaced by silica and other minerals. Over a period of a few million years, those minerals will crystalize. The end result is a rock that appropriates the shape and structure of our original tree. The level of detail we find in some specimens is downright astonishing.
Petrified logs with well-preserved knots, branches, and leaves have been found. Fossil-hunters also come across the occasional log with root structures attached to its base. Moreover, in certain petrified log segments, it's possible to count the growth rings. There's also the matter of coloration. Cross-sections of petrified wood often showcase a glistening rainbow of colors, which is why the fossils are so beloved by artists.
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