This article are notes taken on the Great Lakes of North America, a colossal landform that has fascinated me. The notes are taken from an article by and from the National Geographic documentary, I leave the bibliography at the end.
I hope you enjoy and find useful all the dates that I leave. Now when I read about the native Indians that inhabited this area I will be able to understand its immensity.
Novels and essays that we talked about on the blog and are set in Native North American Comanche and Crazy Horse and Custer
What are the lakes?
The great lakes of North America are 5: Lake Superior, Lake Erie, Lake Huron, Lake Michigan, and Lake Ontario. They account for 84% of the fresh water of all of North America and 20% of the fresh water of the entire planet. Supplying nearly 40 million Americans and Canadians and irrigating a large number of crops.
They contain 22700 billion liters of fresh water.
How were they formed?
They were formed when deep valleys carved out by the advance and retreat of glaciers over thousands of years filled with meltwater at the end of the last ice age.
1,5km thick ice. The ice acts as a plug and the water that passed under it carved the land into channels.
In the upper lake there are rings formed by the water pressing the fine-grained sediments.
Great Lakes Profile
All the lakes are connected. The water enters the upper lake from the northwest, from there to Lake Michigan and Huron, which are two lobes of the same lake. From Huron to Erie where it plunges down Niagara Falls to Ontario, and from there out to the Atlantic via the St. Lawrence River.
It is one of the youngest colossal landforms on the continent. They date from the last ice age in North America. When glaciers several miles thick stretched from southern Kansas to the Arctic and as ice masses receded 11000 years ago, they excavated the basins that were filled with melt and became the Great Lakes. The current contours and drainage systems did not emerge until about 3000 years ago.
The Superior is the largest, the oldest and the least polluted, that is, the best preserved. Even so, the ice is decreasing and the lake is warming. it has sparsely populated banks. It supplies 581000 inhabitants and 9500 million liters are consumed per day.
Its depth is 406 meters
Lake Superiror is the body of fresh water with the largest surface area on the planet, containing more than half of the total water of the five Great Lakes.
Lake Michigan has dangerously clear waters due to invasive mussels that filter out phytoplankton. It supplies 13,3 million people who consume 40900 billion liters per day
It is the only one that is exclusively in the United States.
Manilou Canal on Lake Michigan
Mussels and cladophoric algae. Dead algae release a toxic (produces botulism toxin) lethal to fish and birds.
A cemetery of cladaphoras is produced.
Lake Huron, has a fairly healthy coastline, but there are beginning to be invasive mussels and overexploitation of salmon. It supplies 3,1 million inhabitants with 31600 liters consumed per day
Ferret is the youngest geologically speaking.
In Lake Huron there are subterranean falls larger than the Niagara.
10.000 years ago there were great drops and rises of water.
The climate affects the level of the lake.
In Lake Huron there is a ridge, a limestone mountain range that resisted the ice. It existed when the Paleo-Americans were already living. They have found deposits.
7000 to 8000 years ago it was dry land. They believe that there is a formation of man to hunt caribou.
Lake Ontario has an urban pollution problem. by rainwater and wastewater and by the generation of electricity with plants that use lake water as a coolant. It supplies 10, w million inhabitants and 38900 billion liters are consumed per day.
It is 244 meters deep
The levels of mercury and polychlorinated biphenyls are so high that many of your fish are inedible
5 thousand years ago the water level rose to the current level due to a climate change in the area that brought rain that filled them.
Crack-filled mountain ranges in Ontario indicate that the Great Lakes region is under pressure. There are uprisings. They are signs of seismic activity forming mountain ranges. they are compression fractures. It is not as geologically stable as previously believed. Its size is between 1 and 3 m high and 5 - 10 m wide and many km of lagro. It is all full of uprisings.
There are many very small earthquakes.
At the eastern end, in the San Lorenzo river basin, there is a void. It is the Subdury void, Subdury basin or Subdury structure. It is the second largest impact crater on Earth after the Vredefot crater. It is 1,2 km in diameter
Lake Erie has an excess of nutrients. It is the shallowest of the five, has a high population density on its coasts and high levels of pollution. Runoff from agriculture causes dangerous algal blooms. It supplies 12,2 million inhabitants who consume 26100 billion liters per day. It is the least deep 64 meters
In the summer of 2019, a proliferation of algae covered 1699 square kilometers of lake. These algae can release toxins into the water that cause skin blisters and liver damage.
Long Point has an island formed by sand that crushed glaciers.
Search Lake Eyre Bathymetric Map
It contains 2 numbers, Long Point and Dear crick ?, the 2 are made of sand.
Niagara Falls, 1 million liters of water fall in 135 minute.
Since the glaciers left, the falls have climbed 11 km from Upper Ontario to Lake Eyre.
Extreme weather events
Increasingly, extreme weather events are hitting the Great Lakes area due to climate change and are expected to continue to increase.
Fierce storms lash them like the call millennium storm. Floods due to flooding of the lake level that devastate the urban shore, powerful gales, etc.
In 2016, a storm cut off electricity to the water supply system in Duluth, a city on the shores of Lake Superior, one of the largest bodies of fresh water on the planet.
They are protecting an urban riverbank with 69000 tons of stones to avoid damage, the road is running out and these small towns do not have the budgets to continue recovering it.
Some climate models predict that the number of extreme storms in the world will double for each degree centigrade of global warming.
The temperature differences between the mid and high latitudes that drive the jet stream have been attenuated, causing a deceleration of the air current that has affected seasonal weather patterns, the storms are increasingly sporadic and more intense.
In 1972, with the approval of the Clean Water Law, strict regulations were imposed on wastewater treatment plants that led to the elimination of phosphates from laundry detergents. Algae grow quickly when there is phosphorus. Without phosphorus they do not proliferate.
For 25 years everything went well and after this time there are again algae problems in the Great Lakes due to agriculture.
Instead of plowing the land and fertilizing it with manure every year, farmers were encouraged to use the direct seeding technique. But this type of technique requires granular fertilizers to grow well and the problem is that before the compost is sealed in the earth and now the phosphorus granules remain in the first 5 cm of the earth and when the rains saturate the soil it does so. dissolve and end up in the lakes
And it rains more and more intensely and attempts are being made to reduce runoff from the fields.
Improve monoculture land by planting cover crops in fallow seasons.
Here we link to the documentary Kiss the ground. Kiss the Earth: Regenerative Agriculture that can be seen on Netflix https://www.netflix.com/es/title/81321999
The impact of agriculture
The biggest problem is caused by macro-exploitations the CAFO (Concentrated Animal Feeding Operations)
The Great Lakes basin draws around 1500 billion liters of water daily to irrigate crops. It accounts for 25% of Canadian agricultural production and 7% for the United States.
The total cultivated area is 160,4 million hectares in the United States and 37,8 million hectares in Canada, normally under intensive monoculture. They tend to grow corn, soybeans and hay year after year.
The problem with this monoculture is that as the land is depleted it requires a large amount of compost, the longer a field is used to cultivate the same species, the more fertilizers are needed to replenish the nutrients in the soil.
By fertilizing a lot, nitrogen and phosphorus that are not absorbed by the land through runoff end up reaching tributaries that reach the great lakes. Once there, the algae eat these nutrients and reproduce in a massive way, absorbing sunlight, oxygen and suffocating the fauna. Dead plants and algae rot, bacteria steal even more oxygen by breaking down organic matter.
Excess algae caused by phosphorus forced a large city in Ohio to shut down the water supply.
The great black swamp
A 4000-square-kilometer swamp. It was a natural sink for excess nutrients and at the beginning of the XNUMXth century it was practically completely dried out so that the settlers could cultivate its fertile soil.
Diatoms are algae found in the planet's oceans, rivers, and lakes that generate more than half of the oxygen in the atmosphere, much more than the Amazon rainforest, considered the lung of the world.
Without diatoms the lakes would suffocate and serve as the primary source of food.
Some 3000 species of diatoms have been identified in the Great Lakes and it is believed that many more remain to be discovered.
They use light to convert water and carbon dioxide into simple carbohydrates and are warm foods for zooplankton.
They have discovered a worrying trend, the diatoms of the Great Lakes are getting smaller and smaller. They believe that it is due to climate change, as the water in lakes warms, diatoms have a difficult time floating in less dense surface water and they sink, but when they sink their ability to absorb light decreases.
They are getting smaller and smaller and there is less and they are being replaced by other types of algae of "poor quality" or even toxic
Mussels in Lake Erie have reduced diatoms by 90%
Without diatoms the food web collapses. Less diatoms, implies less zooplankton which implies less fish.
U as superficial gall is lost, the problem will worsen.
Photos that give us an idea of the size of the lakes
Term anishinaabe : zaasigaakwii, refers to when the birds arrive in spring and are suddenly carried away by a storm.
Empty the great lakes
It is a National Geographic documentary, where they tell us about the great lakes and they do a very interesting thing to simulate that they empty them from the data obtained by a side scan sonar.
From these data and those you already know, questions are raised about the formation of this natural mega-structure and what it was like in the past and what its future can be like.
I leave the documentary here (it is no longer on YouTube, I am very sorry) and under the data that I have found interesting.
There is a suspension bridge the Mackinac Bridge that crosses the Strait of Mackinac with 8 km in length between Lake Huron and Michigan.
In the Strait of Mackinac there is a deep 40km x 1km wide channel that snakes between the straits.
Draining Lake Maggiore they see that 5000 to 7000 years ago it was a stream. All the accounts were separated from each other, barely linked by streams.
There are about 6000 shipwrecks around the 5 lakes. The navigation in the 18,19th, 20th and early XNUMXth centuries was very intense. It was the busiest boat route in the world.
Edmund Fitzgerald sinking, the most iconic wreck in 1975. It is the largest ship ever sunk in the Great Lakes. It sank to 163 m with the worst storm in 3 decades. 29 dead that are still inside the bar. It broke in half. They think it sank at 56 km / h
This gives an idea of the outside of the lake and its wild nature