✔️ Important Stuff!

This is an Earthcache-- this means that there is no physical container.  To be able to log this as a find, you must complete the tasks below (Including the photo).  

The Earthcache is located in Cherokee Bluffs Park.  The cache is NOT 24/7.  Hours vary by season, but dawn-to-dusk is a good general starting point.  Please be sure to follow all park rules.

❓ Why are you here?

When I visited the site, I saw what looked like "potholes" here.  I had leanred about them from other Earthcaches and for researching a different Earthcache of my own.  I thought this was an usuual spot for a pothole, so I learned more and want to share!  To help, here is an example of what you are looking for:

🥾 Logging Requirements

To claim a find for this Earthcache, please post your photo with your log and send your answers to the three questions below via geocaching message or email. Do not post the answers in your public log. You may log your find immediately after sending your answers

Photo (Required) : Post a photo of yourself, your GPS, or a personal item with the bluffs and a "pothole" in the background. Note the photo is a requirement.  Logs without photos will be deleted.

Question 1:  Located one of the pits (See photo for example)  Is the bottom of the pit perfectly clean granite, or has it begun to accumulate soil, leaves, and organic debris?

Question 2: Are there other, smaller pits nearby starting to form, or is this the only one? Do you see any evidence of flowing river currents (like smooth, water-polished channels), or does the rock look weathered strictly by standing water and weather?

Question 3: Do you think these are potholes?  If they are, why do you think they are?  If not, what are they and how did the form?

📌 About Cherokee Bluffs

(Note: this introduction section is repeated in each of the Earthcaches hidden here.  Feel free to skip if you are doing multiple EC's...)

Cherokee Bluffs Park in Flowery Branch, GA, features natural granite rock outcrops and cliff overhangs formed from the Piedmont region's crystalline bedrock. These formations sit atop rolling hills, providing distinct topographical features alongside historical significance.  As you walk beneath the massive overhanging rock shelters here (locally known as "Stone Mountain's Toenails"), look closely at the walls of the cliff face.

Key Geological Features

• Granitic Outcrops: The main feature of the bluffs is a massive granite and gneiss outcropping that emerges along the ridge. Sometimes locally compared to Stone Mountain's geology, these formations are composed of minerals such as quartz and feldspar.
• Origin and Age: Like many geological units in Hall County, the underlying rock is part of the Piedmont Province. It formed during the Paleozoic Era when magma solidified several miles beneath the Earth's surface before tectonic uplift and erosion brought the rock to the surface.

📌 Geology Introduction

Welcome to Cherokee Bluffs Park! As you explore the impressive granite outcroppings along the ridge line (locally nicknamed "Stone Mountain's Toenails"), you might notice unique, shallow bowl-shaped depressions carved right into the horizontal and sloped faces of the rock.

At first glance, they look exactly like the circular potholes you find carved into rocks at the bottom of fast-flowing riverbeds. However, we are high above the water table! These structures are actually called gnammas (or weathering pits), and they are a fascinating example of how stagnant rain water and tiny plants can hollow out solid stone over thousands of years.

📖 The Geological Lesson: How Gnammas Form

A gnamma begins its life as a minor, microscopic irregularity or small depression on a flat granite surface. When it rains, water pools in this tiny dip instead of shedding off the rock face.

The formation process relies on a few key steps:

1. Chemical Solution: Granite is made of minerals like feldspar, mica, and quartz. When rainwater sit in a depression, it becomes slightly acidic from absorbing carbon dioxide from the air. This weak acid slowly breaks down the feldspar and mica, turning them into soft clay and leaving behind loose quartz grains.

2. Biological Assistance: As a tiny bit of dirt and moisture accumulates in the developing bowl, organic pioneers like moss, lichens, and small plants (like the little green shoot visible at this cache site!) take root. The acids from their roots accelerate the chemical breakdown, and their roots physically wedge into microscopic grain boundaries.

3. Evaporation and Wind Cleansing: When the sun comes out, the pool dries up. Strong winds or heavy downpours then blow or wash away the loosened, crumbly mineral grains.

Over hundreds or thousands of years, this repetitive cycle of pool, dissolve, crumble, and clear deepens and expands the pit horizontally and vertically, creating a miniature oasis capable of supporting life right on the bare rock.

Why Is the Rock Flaky?

One unusual feature of this outcrop is the brittle, flaky texture of the rock.

Instead of breaking into large solid blocks, thin layers of rock can peel and crumble away from the surface.

How do Potholes Form?

A geologic pothole is a circular or bowl-shaped depression carved into solid bedrock by the erosive action of water. These features form when flowing water traps sand, gravel, and small stones in a natural hollow. As the sediment swirls around in an eddy, it acts like a drill, gradually grinding deeper and wider into the rock over many years. Geologic potholes are commonly found in streambeds and river channels where water flow is strong enough to create the necessary rotational motion.

Are These True Potholes?

Probably not.

True geological potholes usually form in active rivers where swirling water carrying sand and pebbles grinds circular holes into bedrock.

The features here likely formed through differential weathering, meaning some parts of the rock weather faster than others.

Water tends to collect in small depressions and cracks. Once moisture remains in one place repeatedly, weathering speeds up in those locations.

Over long periods of time, these weak spots slowly enlarge into the rounded holes and cavities visible today.

Even without a river, nature can still carve surprisingly smooth and rounded shapes into solid rock.

This happens because the rock contains natural planes of weakness such as:

• Small fractures
• Mineral layers
• Thin bands within the rock

Water can enter these weak areas and gradually loosen the layers.

As pieces flake away, the rock surface becomes rougher and more uneven. Small cracks can slowly grow into larger pits, grooves, and cavities.

The flaky texture of the rock allows weathering to happen more quickly than it would in harder, more resistant rock.