How to log this Cache

1. How did these peices of petrified wood become buried?

2. Why do you think that the method in your previous answer cause this wood to permineralize?

3. Using the earthcache description, what minerals do you think are present in the petrified wood?

4. Take a picture of your GPS, yourself, or some other unique item at the cache zone and upload it with your log. (A photograph is required)

5. Please send the answers to me by message on my profile. You may log this cache as “Found.” (If the answers are not correct I will contact you.)

Introduction

This Earthcache is located in Park City Sunrise Rotart Regional Geologic Park. Here in this park you will learn about the geology of the surrounding area and its modern landscape. On display there are several excellent examples of petrified wood that was discovered here and why it became the way it is now.

Keetly Volcanics

About 30-40 million years ago the area you see around you was a volcanic landscape. Not much remains of the Keetly volcanoes, which have mostly eroded away, however volcanic intrusions known as the Wasatch Igneous Belt strech from the Bingham area in Utah county to Kamas just south of this location. These volcanic intrusions are the roots of the long eroded volcanos and are the geologic proof that the Keetly Volcanos were once here.

Volcanos form most often along or near fault lines and these were no exception. This string of volcanos formed because of the Wasatch Fault that runs north to south from Southern Idaho to Sanpete County, Utah. The Wasatch Fault is also causing the uplift and tilt of the Wasatch Mountains to the east. However, all the volcanos along the Wasatch Fault are now long extinct.

So why is there petrified wood?

Now you've learned about the volcanos that were here so long ago. But why is there petrified wood here? Wouldn't a volcanic eruption burn the trees? Why did they fossilze?

Volcanos erupt in many different ways. We often think about Hawaii's volcanos when a volcano comes to mind. A volcano that spews hot lava that flows down a mountainside destroying everything in its path.

However, some volcanos are much more explosive in nature. Think about Mt. Vesuvius that buried Pompeii in hot ash, or Mt. St. Helens that erupted with a sudden boom in 1980 turning the surrounding landscape into a grey wasteland in a matter of moments.

Trees are affected differently depending on what kind of volcanic explosion kills them. The Keetly Volcanos were more like Mt. St. Helens burying the surrounding area in hot ash. This ash solidified into stone around the buried trees quickly preventing decay. This started the long process of replacing the wood fibers with minerals, a process called permineralization. Mineral rich water infiltrated the cell walls of the wood and slowly replaced the structure preserving intricate details.

Permineralization

Many minerals have been identified in petrified wood, but silica minerals are the most common. This is due to the chemical composition of silica, which binds to the cellulose in the wood's cells. Later, additional silica replaces the cellulose as it decomposes. This slow process allows for even small details to be preserved. After the initial process other minerals at a smaller concentration are sometimes introduced which can change the color of the petrified wood. 

The most common colors in petrified wood include brown, white, grey, and red. Although there are also instances where brighter colors can occur such as blue, yellow, or green. 

Red and Pink colors are produced by the presence of hematite, a form of oxidized iron. - Fe₂O₃

Yellow, Brown and Orange colors are produced by the presence of goethite. - HFeO₂ and Fe₂O₃

Green colored petrified wood is produced by pure reduced iron. - Fe

White and tan are produced by silica. - SiO₂

Black is produced by Organic carbon or pyrite. - FeS₂

Purple and Blue are produced by manganese dioxide. - MnO₂

_{Thanks to my source}