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Placed with Permission from the St. Charles Park Department. Parking is at the posted coordinates. Please respect posted park hours, and stay on the marked trails. You may want to do this cache while simultaneously working on the other earthcache here, GC65HM0.
From the Illinois Nature Preserves Commission:
"Ferson's Creek Fen is a wetland ecosystem situated along the west bank of the Fox River. The preserve lies on a glacial outwash terrace and alluvial stream bed. Two natural communities featured here are meadows and wet floodplain forests. Occupying the core of the natural area, meadows are the prevalent community and range from undisturbed, very high quality portions to segments of moderate quality. Scattered in small "cameo-like" areas of the meadows are the characteristic calciophilic species such as fringed gentian, grass-of-parnassus, Kalm's lobelia, turtlehead and marsh wild timothy. Small bedstraw, great St. John's wort and northern fringed orchid are found in the sedge meadows. Wild rice is located on the edge of the marshy meadow and the floodplain forest."
A fen is a type of wetland. Wetlands are defined as an area of land saturated with water, resulting in a unique ecosystem heavily based on hydric soil and plants- its subcategories are fen, marshes, swamps, and bogs. Both bogs and fens are additionally classified as two types of mire- a wetland with peat-forming plants, and without forest cover. A fen is located on flat, sloped, or depressed land and gets its water from both rainwater and groundwater. A bog, meanwhile, exists in a dome-shape, is elevated relative to nearby land, and gets its water solely from rainwater (a term known as being ombrotrophic).
As mentioned, wetlands form in locations of saturated water. Therefore, the ground beneath a wetland must be impenetrable to water. To this end, limestone cannot hold a wetland (as it is porous), nor can sandstone (water escapes through the gaps in the sand). Granite, shale, and slate all undergo high temperature formation, resulting in the sealing of all pores, making them watertight and thus conductive to wetland formation.
Wetlands fall into three types: Topogenous, Soligenous, and Floodplain. Topogenous wetlands are formed based specifically on the shape of the land, forming in hollows in the ground. These are most common in areas with lower amounts of precipitation. Soligenous wetlands also form in hollows, but are the result of porous rock meeting non-porous rocks beneath. Water flows through the porous rock until it reach the non-porous rock, then spreads outwardly, resulting in springs that feed the wetland. Finally, Floodplain wetlands form in the lower parts of river valleys on gentle slopes. When the river overflows, excess water is collected in a lower area, resulting in the wetland.
Fens primarily consist of grasses and sedges, but can include a wide variety of plant types. The specific types of plants are dependent on water and nutrient concentrations. These plant species thrive on the mineral-rich groundwater or surface water. Fens can be categorized by their pH level: rich fens are alkaline, whereas poor fens are acidic. Rich fens have relatively small meadows and rely on a variety of water sources, while poor fens have more extensive meadows and mosses, and rely on less sources of water.
Fens are formed on layers and layers of peat- soil that partially consists of decomposing vegetation, resulting in the peat being nutrient-rich. Normally when plants and animals die, they are simply recycled into the soil. However, in a mire's perpetually wet conditions, the wildlife remnants instead form peat, providing water and nutrients for future plants to grow upon, which will later add onto the layers of peat and continue the cycle.
To get credit for this earthcache, you must email or message me the answers to the following questions:
1) What kind of meadow can be found at the fen?
2) In which season are native plants re-planted? Why do you think this season was chosen?
3) What kind of animal might live in the meadow here? Why?
4) List 3 kinds of invasive plants.
5) What type of soil exists beneath the peat of the Fox River Fen?
6) Is this a rich fen or a poor fen? Why?
7) What type of wetland is this? Topogenous, Soligenous, or Floodplain?
Additional Hints
(Decrypt)
Gur svefg svir dhrfgvbaf pna or nafjrerq ng gur svefg svir cyndhrf.