I was out with friends and for some reason the factoid that lakes Michigan and Huron are, hydrologically speaking, one lake…nevermind the names.
Looking at a map you can see there is a very narrow link connecting the two but “narrow” is on the order of five miles wide and 120 feet deep at the Mackinac Strait. So it is not a river but rather just a relatively narrow bit compared to the much larger bodies of water it connects.
So what is the official rule on this? One lake that we have given different names to two sides or really two lakes?
If it is one like then it is technically, area-wise, the biggest lake in the world. Bigger than lake Superior (by volume lake Baikal in Russia wins easily largely due to it being ridiculously deep for a lake).
As you noted, hydrologically speaking, they are one lake. But while their connection is a strait big and deep enough to allow the lakes to be one level, it still serves as a bottleneck that slows interactions between the two bodies of water.
And culturally they definitely are (or at least were) two different lakes. So the official answer depends more on what sort of question you’re asking, I guess.
About 7,000 to 9,000 years ago they weren’t as complete as they are now, and there was a pretty big section of land between what is now Lake Michigan and Lake Huron. See this pic about their formation:
The remnants of the river that connected Lake Chippewa with Lake Stanley (the predecessors of Michigan & Huron, respectively) are still visible if you a relief map of the Mackinac Channel.
Also, at one point about 7500 years ago, Lake Michigan/Huron was joined with Lake Superior as well. The combined lake drained via what is now Georgian Bay and the Ottawa River.
Hydrologically speaking, NOAA considers it to be one lake with two basins.
But Mortimer showed that more water flows west-to-east through Mackinac than flows east-to-west, so there’s not 100% freeflow between the two bodies.
And Michigan, at least the lower half of it, tends to be warmer than Huron.
The bigger question to me would be whether the two bodies are home to different species of plants and animals. If they’re distinct enough to be home to different species, then I’d consider them two separate bodies. If not, I defer to the hydrologists.
The entire Great Lakes–St. Laurence system flows west to east / east-southeast.
I watched a video called “Drain the Great Lakes” which showed the lake bottoms with part of the water removed and all of it removed to reveal hidden underwater landscape features. The visualizations on that show what the lakes would have looked like around the end of the last glaciation, and though the GLs were recognizable shapes at that stage, their levels were lower. Lake Huron and Lake Michigan were completely separate. They did not even have a river connecting them.
With rising waters the channel of Mackinac was breached, and it was wide and flat enough to allow Lakes Huron and Michigan to attain a common level. By then the Detroit River would have come into existence too, I think, as part of the systemic west-northwest > east-southeast flow. Stabilized inflow and outflow via Lake Superior and Detroit River/Lake Erie etc. must have favored the common level shared across Mackinac channel. I’m not a hydrologist but I studied it some.
That seems sensible - we do that sort of thing with all kinds of connected entities anyway - from oceans to lakes to body parts - where does your nose stop being your nose and start being your cheek? Where does your forehead start being your scalp?
The Caspian “Sea” would still be larger. Of course, whether or not you want to call that a lake is a divisive issue among people who study such things.
Lake St. Clair is also sometimes considered a Great Lake (at least, it was close enough for whoever named the streets in downtown Cleveland), and Georgian Bay is very nearly a lake.
well, it is in the chain of lakes draining into the Saint Lawrence from Superior and Michigan, but I don’t think an area of 430 square miles qualifies as “great”. You allow that, and Lac Saint-Pierre will want to get in on the act.
