To log this EarthCache and receive credit for it, answer the following questions:
- Feel the surfaces of the petrified wood. Describe how the textures of the different parts feel.
- What different colours can you see in this piece of petrified wood?
- From the information provided below, what minerals do you think are creating the different colours you see in the petrified wood?
- This particular piece of petrified wood is from an area with several rivers and creeks. How might this have promoted the formation of petrified wood?
- (Optional, but appreciated) Post a picture of yourself, your GPS, or something you found interesting during your visit that doesn't give away the above answers.
Please send your answers within a reasonable time after logging.
Update 2 April 2025: Since placement, they've added several more rocks outside of the building. You are looking for the leftmost when facing the building.
So, what is at this location? [1]
The posted coordinates bring you to a large piece of petrified wood located outside of the Hilbun Geosciences building at Mississippi State University. This specific piece of petrified wood was found near Ackerman, Mississippi and donated to the university by the Class of 1920. It serves as a great example for students, especially geology majors, of what petrified wood, which is the official state stone of Mississippi (despite being a mineral, rather than a stone), looks like.
So, what exactly is petrified wood, and how does it form? [2][3]
Petrified wood is formed when a tree is fossilized and turned into stone, creating a replica of the original organic matter. For this to happen, a tree is buried by sediment, which prevents it from decaying due to the absence of organisms and oxygen. Water with dissolved minerals flows through the sediment and over the remains of the tree. When this happens, minerals in the water are deposited in the cells of the plant, a process called permineralization. The soft organic materials inside of the plant are then replaced by the hard minerals, ultimately turning the plant into a fossil and resulting in the formation of petrified wood.
This process is neither quick or instantaneous. Generally, it can take at least 100,000 years for petrified wood to form from a tree. This particular piece, according to the plaque nearby, is approximately 50 million years old. The formation of petrified wood can generally occur in most environments that have the basic materials required for formation. In fact, petrified wood has been found in all 50 American states and on every continent, including Antarctica! Petrified wood can form from entire forest areas, which results in a petrified forest. The United States has several of significant size, including Petrified Forest National Park in Arizona and the Mississippi Petrified Forest, located near Flora, Mississippi.
So, why is petrified wood colourful? [4]
Petrified wood can be various colours. These differing colours are influenced by minerals and other substances in the water and sediment when the petrified wood is forming. Pure quartz, which is composed of silica, appears clear or white, lacking a definite colour. The attached diagram shows how different minerals can alter the colour of the petrified wood. However, even with all of the colours below, there are numerous other combinations that create different colours, depending on the local environment and weather. This means that petrified wood at Petrified Forest NP in Arizona will sometimes have different colours than the petrified wood found in Mississippi.
References:
1. https://statesymbolsusa.org/symbol-official-item/mississippi/state-dinosaur-fossil-state-mineral-rock/petrified-wood
2. https://en.wikipedia.org/wiki/Petrified_wood
3. https://www.geosciences.msstate.edu/sites/www.geosciences.msstate.edu/files/GeologicTimelineMS.pdf
4. https://scienceviews.com/parks/woodcolors.html
Images from Wikimedia Commons and WikiHow