Whitesell Park EarthCache
This earthcache will take you to Whitesell Park and lake. Whitesell is a multi-use park with softball games and a trail. Please note the park hours, 8am to 10pm, park closes at dusk. Parking can be limited during games, so it is recommended tacking this earthcache in the morning. There is no hidden container. You will be visiting the park and answering questions based on your observations and the information provided below. The earthcache is less than 200 ft from provided parking with unlevel terrain.
Logging Task
- Lake Lesson : What is the process that causes a body of water to become overly enriched with nutrients? What are the two most common ones that act like a fertilizer for aquatic life and algae that cause algal bloom?
- Reading the Mud: Examine the soil at the lakebed mud from the floating dock or a few feet from the lakebed. What color does it appear to be? Now take a look at the soil or sediment at the lakebank. Does it match the appearance of lakebed mud?
- Based on the information provided, what geological or chemical factor responsible for the color of the lakebed mud you observed?
- Add a picture from the dock or lakebank with the lake in the background (you do not need to be in it)
Geological History
This area was one part of a 500 acre lake known as Lake Largo. It was drained in 1918 and turned into farmland. The crops thrived in the rich soil but after a harsh freeze it was resold and eventually repurposed for modern recreation. The softball field was developed and a new lake was reformed.
But why was the lake able to reform? Geology is the answer! This little lake has lived many lives, but hidden in its mud and sediment is the story about how lakes form, change, and even fight for balance.
Natural vs Man-Made
For a lake to form the area needs the right geological feature
- A natural depression or low-lying basin, for water to gather
- Soil that is able to withhold water, like clay-rich or low-permeability. If the soil is too fine or porous, like sand or gravel the water will drain away.
- A proper water table, this allowed water to feed into the lake. This can be from a river, rainwater, groundwater or runoff.
When one of these key factors is out of balance the lake can create dead zones and eutrophication. This will cause a geological chemical change in the nutrients and minerals that make up the lakebed mud sedimentary soils.
👀 A Closer Look at Eutrophication and its Effects on Mud
Eutrophication is a process where a body of water becomes overly enriched with nutrients and minerals. These chemicals, like nitrogen and phosphorus, cause aquatic plants and algae to rapidly grow out of control. This is known as an algal bloom. This bloom eventually dies and sinks to the bottom. As decaying bacteria begin to break it down, it consumes huge amounts of oxygen. In an oxygen-rich lake the mud at the bottom acts as a nutrient trap, but without oxygen the mud releases it. This causes a change to the chemistry of the water, lakebed mud, mineral, and surrounding soil. A change you can see!
🧪 The Geochemistry of Mud and Sediment
Lake mud isn't just dirt; it's a living part of a lake's health and serves as a historical archive.
Stuff from the outside: This is called allochthonous material. This is dirt, leaves, and other material that washes into the lake from the surrounding land.
Stuff from the inside: This is called autochthonous material. This is what's created inside the lake itself, such as dead algae, leftover plants, and fish waste.
Lakebed mud acts like a sponge, soaking up and trapping nutrients and minerals. The color depends on the composition of the soil.
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Darkish/black
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Reddish
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Yellow/Brown
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Pale
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Greenish
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a high content of organic matter, nitrogen and phosphorus
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Iron and aluminum oxides
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low to moderate iron and phosphorus
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Calcium,silicate, and very little heavy nutrients
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Low oxygen causing iron and manganese to form other compounds like methane and sulfur. This will give the soil a smell.
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By studying this mix, scientists can learn a lot about a lake's history and what's going on around it.
What was once part of a freshwater lake, then fertile agriculture is now once again a lake teeming with life, both good and not so good. The landscape may have developed by man and nature over time, but the geology of a lake like a low-lying basin and clay-rich soil, are the fundamental building blocks that allow a lake to exist, even a century later.
References
Hand, C., 2016, Dead Zone:Twenty First Century Book, Minneapolis.
Hine, A., 2013,Geological History of Florida: University Press of Florida, Gainesville.
Jones, D., Randazzo, A., The Geology of Florida : University Press of Florida, Gainesville.
Szary, W., 2016, Revisiting Florida’s Geology: A guide to the state’s Geological History, Formation, & Landscapes:Earth2Energy Educational Publishing. Tampa.
https://baysoundings.com/central-pinellas-a-century-ago-lowering-lakes-to-raise-agriculture/?hl=en-US
https://thegabber.com/dam-that-lake
Role of Phosphorus in Eutrophication https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey
Eutrophication | U.S. Geological Survey - USGS.gov,https://www.usgs.gov/centers/wetland-and-aquatic-research-center/science/science-topics/eutrophication
AI Disclaimer: Parts of the text on this EarthCache page were edited with the assistance of AI tools (ChatGPT). AI was used to check scientific sources, ensure against plagiarism, and help craft a lesson that is unique and not duplicative of nearby EarthCaches. The cache owner created, verified, and is fully responsible for all content presented here.