Geology of Lake Michigan
Lake Michigan is the second largest of the Great Lakes. It stretches across 313 miles of shoreline, and contains over 11,000 square miles of freshwater. Located in the Midwest region of the United States, its waters reach an impressive depth of 925 feet. The lake spans four very different states including Michigan, Illinois, Wisconsin, and Indiana.
Formed by the Laurentian Glaciation, Lake Michigan’s landforms have evolved over time. It is believed that the lake is about 15,000 years old and covers an area of more than 22,400 square miles. In terms of geology, the lake is divided into three parts. The western portion is composed of sedimentary rocks, while the central area features shale and limestone formations. The eastern section is comprised of sandstone and shale. The lake bed is made up of sand and silt, while the surficial region is composed of glacial till and outwash.
What is a Lake Flip?
A lake flip is an environmental phenomenon that occurs when an aquatic environment suddenly becomes stratified. Stratification happens when layers of varying temperatures and densities form in a body of water. In the case of Lake Michigan, this usually occurs towards the end of the summer when the thermoclines –the area of a lake where the temperature of the water changes–are pronounced. The stratification process is driven by the sun’s heating of the surface water, which causes a warmer, lighter layer of water to float on top of the cooler, heavier layer of water below.
When the two layers are sufficiently separated, the lake will flip. This has a dramatic effect on the lake as it prevents oxygen exchange and hinders the movement of nutrients. The lake will remain in this state until the weather changes and the layers of water can mix. This phenomenon typically last a few weeks until the lake is flipped back to its original condition.
Causes of Lake Flipping
Lake flipping is primarily caused by the sun’s heating of the lake surface water. As the lake’s temperature increases, the lake’s thermocline also deepens, creating a distinct boundary between the warm and cool layers of water. As this boundary builds, the lake will eventually flip, creating strata of water.
The amount of sunlight, as well as the surface area of the lake also affect a lake’s propensity to flip. Generally, larger bodies of water are more likely to stratify due to the influence of the sun’s rays. This is especially true of Lake Michigan, which is relatively large and receives substantial amounts of light.
When Does Lake Michigan Flip?
Lake Michigan usually flips in late summer. Because of the lake’s size and the prevalence of sunlight in this region, the water temperature can rise quickly, leading to stratification.
The exact timing of an offshore or inshore flip also depends on many outside factors, including wind and other weather patterns. These can create different levels of turbulence in the water and alter the stratification process.
In general, however, Lake Michigan will flip in August or early September and will remain in this state for a few weeks before the temperature and density layers mix again.
Effects of Lake Flipping
Lake flipping can have both positive and negative effects on the lake’s ecosystem. On the positive side, it can help reduce the growth of algae and protect against the spread of invasive species.
On the negative side, it can disrupt oxygen exchange between the two layers and create hypoxic conditions–low oxygen levels. This can lead to the death of aquatic animals living in the deeper, cooler layers, and can affect the entire ecosystem as a whole.
The stratification can also cause a decrease in oxygen levels in the lake as a whole, leading to a decrease in dissolved oxygen levels and an increase in organic material.
Solutions for Stratification
One solution for mitigating the negative effects of lake flipping is through processes like aeration and bottom-up circulation. If a lake has been stratified for a long period of time, a process of mixing the layers of water may need to be conducted by stirring or aerating the lake. This helps to increase the oxygen levels and prevents the buildup of organic material.
Bottom-up circulation is another method of breaking stratification, which involves pumping water from the deeper layers of the lake to the surface. The deeper water is typically much colder than the surface water, which causes the stratification to break and encourages oxygen exchange.
Reducing Lake Flipping
To reduce the frequency of lake flipping, there are several measures that can be taken. Limiting activities like boat wakes and motorsports near the lake can reduce the amount of turbulence in the area and prevent stratification.
In addition, controlling the amount of pollution entering the lake can prevent the water from becoming too warm, which helps to limit stratification. Limiting development around the lake’s shoreline can also reduce the amount of runoff entering the lake and further contributes to temperature control.
Finally, adding oxygen to the lake can help to increase dissolved oxygen levels, which can help to slow the stratification process.
Effects on Local Ecosystems
The effects of stratification on local ecosystems can be quite severe. With oxygen exchange disrupted, aquatic species may die off as their food sources are also disrupted. The decrease in oxygen can also make it difficult for nutrients to move around the lake. This can lead to a decrease in primary productivity, meaning fewer organisms will be able to survive in the lake.
Stratification can also lead to a decrease in the amount of habitable habitat for aquatic species. The decrease in dissolved oxygen can increase competition between species, pushing them out of their usual habitats and closer to shore. This can be particularly detrimental to shore-breeding species.
Effects on Local Wildlife
The period of stratification also has severe impacts on local wildlife. The lack of oxygen and nutrients in the lake can lead to a decrease in the number and diversity of aquatic bases such as fish and insects. A decrease in food can mean a decrease in wildlife populations.
Waterfowl, in particular, can be heavily affected by a decrease in food sources. Warming can also drive them away from their breeding grounds, which can have devastating effects on their populations.
Effects on Local Human Habitation
For local inhabitants, the effect of a flip on Lake Michigan is often felt through a decrease in recreational activities in the area. Boating, fishing, and swimming can become dangerous during a period of stratification, as the lack of oxygen exchange can cause water to become stagnant. The increase in organic material can lead to an increase in odor and an unpleasant experience for swimmers.
Moreover, the increase in organic material can also lead to an increase in mosquitoes in the area, posing a potential danger to residents. Additionally, the decrease in dissolved oxygen can increase the risk of algal blooms and the spread of other waterborne pathogens, making it difficult and unappealing to enjoy the lake.
Conclusion
Lake Michigan flipping is an environmental phenomenon that can have far-reaching effects on the region. Although an increase in water temperature is the primary cause of stratification, other factors such as the amount of sunlight, surface area of the lake, and outside weather patterns can also play a role. Stratification can cause severe disruption in the lake’s ecosystem, impacting both aquatic species and the habitat for local wildlife. In addition, the decrease in recreational activities can pose a risk to local human habitation and further disrupt the local environment. In order to reduce the frequency of Lake Michigan flipping, several measures may need to be taken, including reducing boat wakes and pollutant runoff, controlling development near the lake, and increasing oxygen levels.
