***Welcome to my first ever hide!*** Please note that parking is available mere feet away from GZ.
The purpose of the Skokie Marsh Earthcache is to teach you about the geological history of what are today known as the "Skokie Lagoons". In reality, you stand today on the soil of the Skokie Marsh, an area that spans across western Winnetka, Glencoe, and Highland Park. In this earthcache you will learn a bit about the geology and function of marshes, lagoons, and will think about whether the Skokie Lagoons fit the criteria of 'lagoon'. Let’s start with some definitions:
What is a Marsh?
Broadly speaking, a marsh is a type of wetland that is dominated by herbaceous plants rather than woody vegetation. Marshes can be freshwater or saltwater and are characterized by waterlogged soils and the presence of standing or slow-moving water. Marshes provide critical habitats for a variety of wildlife, including birds, amphibians, and numerous plant species.
Types of Marshes
There are generally considered to be two types of marshes:
Tidal Marshes: Tidal marshes are found in coastal regions. They can be freshwater but are usually saltwater. In the US, they are most prevalent on the east coast, but some are also present on the Gulf Coast. Tidal marshes provide storm and flood protection, help with excess nutrient drainage, and offer habitat to many plants and animals. Urban development and pollution have hurt tidal marshes, but they have rebounded in recent years due to various conservation efforts.
Non-Tidal Marshes: Non-tidal marshes are the most common wetlands in the US and North America. They are usually freshwater marshes, although some are brackish/alkaline. They frequently occur along streams in poorly drained land depressions. Water levels can vary from a few inches to several feet, and some marshes may periodically dry out completely. Non-tidal marshes are incredibly biodiverse and play a role as a natural flood mitigation and excess nutrient filtration mechanism.
What is a Lagoon?
Lagoons are generally agreed upon to be any shallow body of water separated from a larger body of water, such as a sea or ocean (or in this case Lake Michigan), by a barrier of land or tidal barrier such as sand or reef.. Lagoons often have brackish water, a mix of saltwater and freshwater, although some are entirely freshwater. They typically feature calm waters due to the protective barrier.
Types of Lagoons
Lagoons are classified into 3 main types; Restricted Lagoons, Choked Lagoons, and Leaky Lagoons:
Restricted Lagoons: Restricted lagoons are partially enclosed water bodies with limited exchange between the lagoon and the open water. This limited exchange is typically due to narrow or infrequent inlets.
Choked Lagoons: Choked lagoons have even more limited exchange with the open sea compared to restricted lagoons. They are often connected to a large body of water through very narrow and sometimes obstructed channels.
Leaky Lagoons: Leaky lagoons have wide inlets or multiple connections to the open water, allowing for substantial water exchange. This exchange helps to stabilize salinity and temperature, creating a more homogeneous environment.have wide tidal channels, fast currents and unimpaired exchange of water with the larger body of water.
Debate about the ‘nature’ of lagoons
Historically there has been some disagreement on the technicalities of what defines a lagoon. Some authorities include freshwater lagoons in their definition of a ‘lagoon’, while others don’t. Scholars have also disagreed on the differences between the terms ‘lagoon’ and ‘estuary’ - some scholars such as Richard Davis say that what makes a lagoon distinct from an estuary is its lack or near lack of fresh water inflow, and lack of tidal flow. Other scholars state that lagoons can be identified when parallel to a coast, whereas estuaries are perpendicular to coastlines. Moreover, the word ‘lagoon’ translates in a variety of different ways in different languages. Scholars in the English speaking world do tend to agree, however, that a lagoon is always a shallow and elongated body of water separated from a large body of water by a stretch of land, shoal, or reef.
Why are they called the Skokie Lagoons? Are they truly ‘lagoons’?
While their name would indicate that they are indeed lagoons, the reality is a bit more blurry. At face value, the Skokie Lagoons fit the criteria of being lagoons. They run perpendicular to Lake Michigan, are fairly shallow (with an average depth under 6’), and are not directly connected to Lake Michigan. Yet, these lagoons are not saline, and by the hand of mankind are a transformed version of the historical Skokie Marsh wetland. I discuss the transformation of the Skokie Marsh into the Skokie Lagoons below:
History Lesson
In the early 20th century, efforts were made to convert the marsh into a more manageable and useful landscape for the suburban Chicago sprawl. Several driving factors behind this effort were reducing mosquitos, creating opportunities for outdoor recreation, and flood control.
Between 1933 and 1940, the Civilian Conservation Corps (CCC) - a public work relief program part of President Franklin D. Roosevelt's New Deal - undertook the ambitious project of draining this area of the marsh and creating a series of lagoons. In what was the largest public works program in the country during the Great Depression, they constructed dams, dikes, and channels to control water flow and created the system of seven interconnected lagoons that you see today.
The Skokie Lagoons Today
Today, the Skokie Lagoons are a beautiful and serene natural area, popular for boating, fishing, bird watching, walking, and of course geocaching. The lagoons are now a managed system, with man-made structures like dams and channels that control water flow and maintain stability of the ecosystem. Yet if one looks closely, the natural marshy landscape is clearly visible.
Earthcache Logging Tasks
To log this Earthcache, please visit the posted coordinates and take a moment to observe the area. Then, please message me your answers to the below questions using your observation skills and the information above:
- Describe the land in front of you between yourself and the shore. What trait of the ground in front of you can you identify that is indicative of historical marshland in the region? Hint: Think about a defining trait of marshes.
- Do you think the Skokie Lagoons should be called ‘lagoons’? If no, then why not? If yes, then how would you classify the Skokie Lagoons (restricted, choked, or leaky)?
- Take a photo at the plaque at the coordinates and attach with your log. You can take a photo of your thumb/caching item/caching name if you don’t want to show your face.
With the exception of your photo, please do not post your answers in your log.
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