Strong Hall Rock Garden: a Story of Geologic Time in East Tennessee

At the cache location you will find displayed 18 examples of rocks telling the story of geologic changes in East Tennessee from 1.15 billion to 325 million years before the present day. This unique and educational collection is arranged in chronological order and serves as a great timeline of our region's geologic history.

The geology department at the University of Tennessee put together this rock garden outside the new Strong Hall in 2017, and my geology professor and his colleagues in the department are thrilled to have more people learn from the collection of rocks here. While not required for this cache, I do recommend heading to the 7th floor of Strong Hall to see another rock garden, excellent diagrams and maps on the walls, and a great view of Knoxville and the mountains.

This earthcache is available at all times but parking can be challenging during the school year. Be sure to park legally and reference the waypoints for nearby recommended parking. Also, there is no need to leave the sidewalk or touch the rocks to complete this earthcache. Use your eyes and leave the rocks as you found them! Thanks to the geology department for putting together this rock garden and to the generous donors who gave these specimens for students and visitors to enjoy and learn from. 

If you were to map the locations where each rock in this garden was collected onto the above map you would see a trend. The oldest rocks would be at the peak of the Appalachian Mountains and the rocks would be consistantly younger the farther their origin is to the peak. The colors on the geologic map above visualize that for us, showing the ages of the rocks below the surface.

The rocks in front of you were formed millions of years apart and were formed through various processes. This earthcache aims to highlight a few of these all in this one location and help geocachers be able to read a geologic map. The three rocks highlighted in the logging requirements below each were formed in drastically different events at varying periods throughout Earth's history, yet they all were collected from locations less than 70 miles from each other here in East Tennessee. I hope this stop gives you some perspective into the diversity of the rocks just below the surface in our region.

From your own observations of the rocks as well as information from the corresponding plaques, please send the answers to the following questions to me in the form of a message (preferably on the same day you log your cache find):

1. Locate rock #1. This chunk of Gneiss is not only the oldest rock in this garden but one of the oldest types of rock found in the Appalachian Mountains. It was formed over one billion years ago, miles beneath the Earth's surface. It and the layers above were pushed up in the collision that formed the Appalachians. They finally became exposed to the surface after the elevated layers of the Appalachians above weathered away over the past 300 million years.

    a.) What other two colors is this rock besides cranberry/orange?

    b.) Is this rock weathered/smooth or broken/rough?

2. Locate rock #13. This rock has numerous traverse ridges across the face of it that called trace fossils. These fossils are a result of organisms tunneling through a muddy and sandy substrate within a shallow marine environment. At the time of its formation, the area that is now the Cumberland Plateau was likely a submerged basin of warm ocean water (similar to today's Bahamaian Islands) before collision lifted the Appalachians.

    a.) Which of the three classifications does this rock fall under?

    b.) What is the approximate diameter of the trace fossils on the face of the rock?

3. Pick any other rock in the garden and provide answers to the following questions about it.

a.) What is the name and estimated age of this rock?

b.) What processes do you think created this rock?

I hope this earthcache helps visitors learn about the age of rocks relative to their location in Tennessee and what condidtions in which each rock was formed. If you want to lean more, here are the sources I referenced in writing this description:

https://pubs.usgs.gov/sim/2997/pdf/SIM2997.pdf

https://www.radford.edu/~fldsch/RUFieldschool/formationpages/Cranberry%20Gneiss/Cranberry.html

https://en.wikipedia.org/wiki/Geology_of_the_Appalachians#Mesozoic_Era_and_later