Geology of Cloudland Canyon Project

The Geology of cloudland canyon

SOPHIE FORBES AND MADDIE HURD

This interactive presentation is intended to serve as a guide to the geology of Cloudland Canyon in the northwestern corner of the state of Georgia, United States, near the city of Trenton. The geology of this area is interpreted based on observations regarding the sedimentology of the outcrops and the associated depositional environment of each facies. Information gathered from additional sources is utilized to enhance and corroborate interpretations based on observations from the field.

Here is a map of the route we took on our visit to Cloudland Canyon State Park. All observations were made along this route. In detail, we hikes to Main Overlook and Overlook #2, completed a portion of the West Rim Loop, and hiked down into the canyon as far as Cherokee Falls.

Map of Cloudland Canyon looking southward, up the canyon.

Marked on the map are places of geologic significance, accessible by the State Park trails.

Take a look at the interactive version of this map on the following pages to learn more about the geology of each location!

map area on next slide

Each of the outcrops highlighted on this map are at approximately 1,700 feet elevation, and three of them contain a visible channel deposit, characterized by massive sandstone of medium to coarse sand-sized grains.

Hover over each circle to see a picture of the correlated outcrops.

Comparison to Geologic Guide

We compared our findings to a geologic guide to Cloudland Canyon State Park (Griffin and Atkins, 1983). The guide explains that most of the sand and mud seen in the outcrops was deposited in a deltaic environment, which transitioned to a fluvial system on land. This is consistent with many of our observations of channel deposits at outcrops #2, #3, #4, and #5, as well as the varying tidally influenced facies that we saw below the channels (we can assume that a delta environment may have experienced strong tidal influence in addition to unidirectional current). The guide also details a particular outcrop that displays a filled channel deposit overlying marine facies influenced by tides, which is likely the same outcrop that we call outcrop #5. “Differential erosion” (what we called differential weathering) is described in relation to the canyon walls and the slope-forming shales versus the cliff-forming sandstones that are more resistant to erosion. The guide also mentions the abundance of talus at the bottom of cliffs deeper in the canyon, which we found in abundance near Cherokee Falls (this is where we saw beautiful trough cross-stratification). In contrast with the geologic guide, we saw some facies (specifically at outcrop #3) that we thought may have been deposited from an estuarine environment, though the evidence that led us to believe this may also be characteristic of a deltaic environment.

(Griffin and Atkins, 1983)

History of Sea Level Change

Cloudland Canyon is situated within the Appalachian Plateau geologic province, in the northwest corner of Georgia (Clark 2009). During the Pennsylvanian period, which began around 325 million years ago (Griffin and Atkins 1983), a shallow inland sea covered much of what is now the United States (Clark 2009). The sandstone and mudstone marine facies at Cloudland Canyon formed during the millions of years in which this inland sea covered the area (Clark 2009). The Pennsylvanian is characterized by cyclic sea level change, influenced by Southern Hemisphere glacial cycles and periods of global warming and global cooling (Cecil et al. 2014). The deposits seen within Cloudland Canyon document this history of sea level change; for example, the tidally influenced deposits covered by incised river valley deposits show a time of rapid sea level fall. Beginning around 270 million years ago, the North American Plate and the African Plate collided, producing the Appalachian Mountains (Clark 2009). The Appalachian Plateau is an uplifted portion of the Valley and Ridge geologic province, and formed during this orogeny (Clark 2009). The joints seen in multiple outcrops are evidence of the mountain-building event. Today, within the Appalachian Plateau, deposits of resistant sandstone stand as ridges and cliffs whereas deposits of weak mudstone and limestone are often weathered into valleys and fertile soil (Clark 2009).

Acknowledgements

We would like to thank Quentin Spencer and Emma Sprigle for their assistance on our field trip as trusty and knowledgeable companions, as well as their readiness to pose for scale in our pictures. We would also like to thank the professor of Introductory Geology at Georgia State University for his shared insight and willingness to answer our questions. Additionally, we would like to thank Dr. Holland and Samantha Khatri for teaching us everyhting we know about Sedimentary Geology.

References

• CECIL, C. B., DIMICHELE, W. A., and ELRICK, S. D., 2014, Middle and Late Pennsylvanian cyclothems, American Midcontinent: Ice-age environmental changes and terrestrial biotic dynamics: Comptes Rendus Geoscience, v. 346, p. 159-168. https://doi.org/10.1016/j.crte.2014.03.008
• CLARK, S. H. B., 2009, Birth of the mountains: The geologic story of the Southern Appalachian mountains: Denver, U.S. Geological Survey, p. 2-20. https://pubs.usgs.gov/gip/birth/birth.pdf
• GEORGIA DEPARTMENT OF NATURAL RESOURCES and GEOLOGIC AND WATER RESOURCES DIVISION, GEORGIA GEOLOGIC SURVEY, 1997, Geologic map of Georgia: Atlanta.
• GRIFFIN, M.M. and ATKINS, R.L., 1983, Geologic Guide to Cloudland Canyon State Park: Geologic Guide 7, Department of Natural Resources, Environmental Protection Division, Georgia Geologic Survey, p. 1-35.
• Google Earth Pro
• HOLLAND, S., 2023, GEOL 4500: Sedimentary Geology Syllabus. http://strata.uga.edu/4500/index.html

Thank you!

Outcrop #2

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Close-up of Outcrop #2

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Outcrop #3

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Outcrop #5

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Outcrop before Cherokee Falls

Cherokee Falls

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Cloudland Canyon documents a complex history of a marine environment that was later uplifted and eroded. Daniel Creek is a powerful erosive force that has exposed thousands of feet of cliff face and sedimentary facies.

East Rim

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