Wood to Stone - Petrified Forest National Park EarthCache
Hidden : 12/6/2024
Difficulty:
2 out of 5
Terrain:
1 out of 5

Size: Size: other (other)

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Geocache Description:


In this Earth Cache you will examine a sample of petrified wood and determine the minerals that were present when this wood was transformed into stone. The sample is outside the gate to the park, at a parking lot / turn around and is handicap / stroller accesible. There is no need to enter the park to complete this Earth Cache. You will also be tested on your mastery of the reading material.

Petrified Wood




Image: National Park Service

Petrified Wood (from the Greek petro, meaning rock or stone) is the name given to a particular type of fossilized wood. Petrification is the result of the organic material of trees or tree-like plants having been replaced by minerals. These minerals, carried by water, fill spaces within the organic material and eventually replace it. This can occur if the tree is immersed in mud, silt, or volcanic ash; this shields the dead tree from oxygen, which is necessary for the fungi and bacteria that are the drivers of decomposition and decay.

The Triassic Period




The Triassic Period spans about fifty million years, from the end of the Permian Period (250 million years ago) to the beginning of the Jurassic Period, 200 million years ago. The Triassic began with the Permian-Triassic Extinction, one of the greatest extenction events in the history of our planet. This period was dominated by reptiles, and among those were the first dinosaurs that walked the Earth. Most of the fossils and petrified wood in Petrified Forest National Park dates from this period. At this time the land that would become North America was part of the supercontinent Pangaea, which later separated into Laurasia and Gondwanaland.

The Petrified Forest




Image: paleonerdish.wordpress.com

Two hundred million years ago, this land was a lush forest, with forests of tall conifers fed by enormous rivers. As these trees died or were knocked down by wind or water, many were carried downstream and buried by layers of sediment. Thus protected from the organisms that drive decomposition and decay, the wood soaked up groundwater and silica from volcanic ash that eventually replaced the organic material. The result is one of the most complete records of the fauna of the late Triassic on Earth. Hundreds of Triassic species have been identified here. Hard as rock - well, they are rock - and glistening with every color of the rainbow, they tell us much about this ancient land.

The Color Of Wood




The color of the petrified wood is an indicator of the minerals that were present during petrification.

  • Black often indicates the presence of carbon.
  • Shades of blue or green are typically due to copper, cobalt, or chromium.
  • Yellow hues are often caused by manganese oxides.
  • Pink and purple are due to manganese.
  • Shades of red, yellow, and brown shades are created by iron oxides.

Earth Cache Questions


To complete this Earth Cache, please send your answers to these questions to the CO. In addition, as per current Earth Cache guidelines, please post a picture of yourself and/or your crew at the Earth Cache location.

(1) In your own words, describe how this tree became petrified.

(2) Examine the colors you see and speculate as to the minerals that were present when this sample was petrified.

Sources


Petrified Wood (Wikipedia)
Petrified Forest National Park (National Park Service)
Triassic (Wikipedia)

Additional Hints (No hints available.)



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