For this Earthcache, I am going to concentrate on the Kettle Lake and Eutrophic Ponds along the trail. The Pat McGee trail runs along the East side of Linlyco Lake. Linlyco Lake, according to the signage, is a Kettle Lake. Kettle Lakes are formed as a result of large blocks of ice (bigger than icebergs) being left behind from retreating glaciers. According to the Executive Director of the Pat McGee Trail, the lake and the surrounding acreage was purchased in the late 1940's by the Lincoln Lyon Company. The name of the lake is taken from the name of the company. The Lincoln Lynn Company sold lots around the lake but the ownership of the lake itself still remains in their family. The depth of most kettles is less than 32 feet; Linlyco Lake is only 8 to 10 feet deep and it covers about 13 acres.
There are several Eutrophic Ponds along the trail. While there has been much work done to prevent erosion from filling in the lake, the ponds have been changed over the years due to erosion in the area. The sign at the waypoint will tell you about the eutrophic ponds and the plants and fish that thrive in them. As you travel along the trail, see if you can spot other eutrophic ponds aside from the one at the sign. They will look different at different times of the year, depending on the season as they often dry up in the summer if there isn't sufficient rainfall.
Kettle Lakes
Kettle lakes were formed when glaciers were retreating from southern areas - moving backwards. Large pieces of ice (larger than icebergs) broke from the glacier and were left behind. As streams of meltwater from further north flowed away from the glacier, they carried with them gravel, sand and even boulders and deposited the sediment around the ice block to form broad outwash plains called sandurs. This outwash partially or completely covered the ice that was left behind from the glacier.
Most kettles are less than 33 feet deep but they may be up to 150 feet deep, they range in size from 15 feet to 18 miles in diameter and they are usually circular in shape because melting blocks of ice tend to become rounded. In most cases kettle holes fill with water, sediment, or vegetation. If the kettle is fed by surface or underground rivers or streams, it becomes a kettle lake. If the kettle receives its water from precipitation, the groundwater table or both, it becomes a kettle pond (or kettle wetland if vegetated).
Definitions:
Glacial outwash - generated when streams of meltwater flow away from the glacier and deposit sediment.
Sandurs - outwash plains formed by the glacial outwash deposits.
Kettle holes - depression in a glacial outwash drift made by the melting of the detached mass of glacial ice that becomes partially or fully buried.
Eutrophic Ponds
Pond Eutrophication is commonly known as pond stagnation or the natural aging process of a pond. This can occur naturally or it could be caused by human interaction. Natural pond eutrophication occurs when rainfall erodes the nutrients from the soil around the ponds edge into the water. Human involvement usually speeds up the natural aging process of a pond stagnation by releasing nutrients such as phosphorus into ponds from run off.
Over time, unless they have continued input from a fresh water source, closed aquatic ecosystems often become eutrophic. As a pond becomes covered with surface vegetation, the organic matter settles at the bottom, slowly filling up the pond and causing low dissolved oxygen levels as decomposition takes place.
A Eutrophic body of water usually has a soft mucky bottom. Due to the excessive nutrients, especially nitrogen and phosphorus, these water bodies are able to support an abundance of aquatic plants. Usually the water body will be dominated by either aquatic plants or algae. When plants dominate, the water tends to be clear; when algae dominates, the water tends to be darker. The algae engages in photosynthesis which supplies oxygen to the fish that may be living in the water.
To claim a find on this earthcache send me the answers to the following questions:
At the posted coordinates answer the following questions:
1: In observing the lake and using the description of kettle lakes and ponds, do you think this lake is fed by underground rivers and streams or by precipitation and the groundwater table?
2. Estimate the diameter of the lake.
At the additional waypoint answer the following questions:
3. What are three of the characteristic plants found in a eutrophic pond?
4. What are the characteristic fishes found in a eutrophic pond?
5. After reading the information about eutrophication, observe the eutrophic pond here - do you think erosion caused the eutrophication or do you think it was caused by human interaction?
I request that you email your answers to me on the same day that you log your “found it” log. (This does not have to be the day you visit, just the day you log the find on the computer.)As per Earthcache rules, I must delete your log if I don't receive your answers within five days of your visit.