Logging Requirements
To log this EarthCache, visit the posted coordinates at the central canyon floor and answer the following questions based on your on-site observations. Please send your responses before logging your find to me via the Geocaching message center or email. And as always, please be respectful of the natural features while you're exploring.
At the posted coordinates, face east and look down to observe the lignite here.
- Describe the lignite's appearance—color, texture, and layering—and estimate its thickness.
- What does its presence suggest about the past environment in this area?
- Walk south about 25'-30' along the canyon floor and observe the lignite here. Do the lignite features change? If so, describe what you notice.
To complete this EarthCache, please include a photo of yourself, your group, or a personal item at the posted coordinates with your log.
- Make sure your answers to the questions above are not visible in the photo.
Arkansas Little Grand Canyon
Located just beyond the dam and spillway at Lower White Oak Lake, this beautiful site offers a chance to see lignite up close. The rock layers here are part of the Cane River Formation, a geologic unit dating back to the Tertiary Period (approximately 66–23 million years ago). This formation records the dynamic shifts of ancient environments, from swamps and floodplains to shallow marine waters. As you stand on the central canyon floor, take a moment to look around at the walls and creek beds of exposed lignite. Each layer of these walls tells a part of the story of this landscape.
After exploring the canyon floor, take a short walk to the nearby spillway (trust me, you want to do this), where you can see water still at work reshaping the land. There’s also a nice 0.4-mile trail that loops around the Little Grand Canyon, giving you different views and plenty of photo opportunities. Note: A trail map provided by White Oak Lake State Park has been uploaded for reference.
Lignite
Lignite is a type of coal that forms from compressed plant material and is considered the lowest rank of coal in terms of energy content. It’s sometimes called “brown coal” because of its earthy brown color and crumbly texture. Lignite forms over millions of years when peat (partially decayed plant material found in wetlands) is buried under layers of sediment. As heat and pressure increase, the peat slowly transforms into lignite. However, it doesn’t get as compact or energy-rich as higher-grade coals like bituminous or anthracite.
Lignite contains a high amount of moisture, sometimes nearly 50% of its weight, which lowers its energy output and makes it less efficient and more polluting to burn compared to higher-grade coals. Its soft, crumbly texture also makes it difficult to transport over long distances as it tends to break apart during handling. For this reason, lignite is typically used for electricity generation in areas where it is mined locally, often with power plants built nearby to reduce transportation costs. While not the most efficient or clean-burning fuel, lignite has played a significant role in energy production in regions such as Texas, North Dakota, and parts of Germany where large deposits are easily accessible.
Lignite is present underground in southern Arkansas and certain regions of the state, such as the West Gulf Coastal Plain and Crowley’s Ridge, contain significant near-surface deposits. However, there are currently no active lignite mining operations in Arkansas and no plans for development in the foreseeable future. Lignite is not part of an indicated reserve at the Arkansas Little Grand Canyon. The nearest deposits with potential are located at Barham Lake, Lester (Ouachita County), and Panther Creek, all within roughly a 30-minute drive from this location. Although it isn’t mined in this area today, lignite remains an important indicator of the region’s geologic history.
Acknowledgments
This EarthCache was written based on GSA and Geocaching guidelines. Permission for this EarthCache was granted by Poison Springs State Forest. A very special thank you to the Office of the State Geologist and AllThingsEarthCache for their guidance and expertise in order to successfully create this EarthCache.