Missing Islands ???

[Bigb23]

I was just watching a History Guy Doc on YouTube about the founding of Detroit by Cadillac. This map puzzled me because of the Islands smack in the middle of Lake St. Clair!
I know cartographers of the time could be way, way off. But this?

What happened, dredging? High water levels? Those islands are huge.

Unknown date of map.

[Jimaz]

Here's the video:

Antoine de la Mothe Cadillac and the Founding of Detroit

The map appears at the 10:00 mark.

A topographic map might help. I'm looking for one at USGS.

[Meddle]

Shorelines look different. Maybe much lower water levels then? Maybe those island are just marshy areas barely above the water surface?

[jcole]

This lone, large island in a map from a time before the above makes it even more curious

[Jason]

In real life the area around Alganac has a lot of weird rivers and marsh and islands and stuff, and so I think the map just has a really bad understanding of that area.

[Bigb23]

This lone, large island in a map from a time before the above makes it even more curious

You can see where they built I-75.

[Meddle]

The gang here might know something:

https://www.glerl.noaa.gov/

[Meddle]

You can see where they built I-75.

No, that's nature's sewerage drain line. Crap flows downhill.

[Bigb23]

Mackinaw City might disagree - unless they can blame it on the tourists.

[Bigb23]

Jimaz - Here's the video:

My clean up guy !

[Gistok]

Those islands are probably just the seaway islands otherwise known as the St. Clair River delta. Interestingly enough that delta is known as the largest freshwater delta in the world.

The seaway islands have undergone many changes over the last 3 centuries, partly because the dredging of the shipping lanes mostly ended up to form even more islands in the delta. I think that the largest of those islands on the old map is actually Walpole Island, on the Canadian side, and like the map of Michigan shown in the old 18th century maps of Michigan, the mapping of the islands left a lot to be desired.

[Bigb23]

I can't see the discrepancy of 200 years.

[Jimaz]

Those islands are probably just the seaway islands otherwise known as the St. Clair River delta. Interestingly enough that delta is known as the largest freshwater delta in the world....

I think that's the case here.

It must have been frustrating trying to navigate using maps like that. There's another one that shows California as a giant island separate from the continent!

[Dan Wesson]

Atlantis maybe?

[MikeM]

I was just watching a History Guy Doc on YouTube about the founding of Detroit by Cadillac. This map puzzled me because of the Islands smack in the middle of Lake St. Clair!
I know cartographers of the time could be way, way off. But this?

What happened, dredging? High water levels? Those islands are huge.

Unknown date of map.

That's the "Buffalo Map" made by Cadillac in 1702. If you could see the entire map, there is a Native American hunter shooting an arrow at bison in the lower left corner.

And yes, just like most maps of unexplored lands in the era, the shapes, areas, distance, and directions are all wacked.