beach sand versus dune sand

John Madill

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SW MI
There is a very long freshwater beach near me. And it is very busy. Behind the beach is a very tall sand dune. It is nearly 250 feet tall. And steep.

Visitors love to slowly climb to the top and then run, roll, etc, down to the bottom.

So my question is about the things dropped into the sand. On the flat beach i imagine the drops work their way straight down over time.

What happens on steep sandy slopes? Are they moving down the hill? do they get increasingly deeper?

What part of the dune is best for searching, the bottom or the whole thing?

thanks!
 
I have a similar situation in a local park that I hunt in the mountains. I find things on the whole slope and most is near the bottom. Of course, this is dirt and not sand so I'm not sure how the movement in sand would be.
 
The whole thing, just don't get swallowed up like that kid in Indiana did a few years ago.
Quite an interesting read if you want to google it. A scientist studied it afterward and learned a lot about sand movement.
 
I imagine a ring for example would carry down the dune for a long way initially due to it's momentum. Then people after it would knock it down further, but it would also bury into the sand then until it hit a layer that was solid enough to trap it.
You should dig a test hold into the base and see if there's such a layer. If it's just soft sand you'll need a lot of errosion, and not being the water that would come from wind.
 
The dune should have a windward and a leeward side. If the surrounding terrain is essentially flat (except for the possibility of other dunes), with the dune being developed on that surface, the dune will likely have a steeper side and a gentler slope on the other side. Most folks like to play on the steeper (leeward) side. The gentler (windward) side frequently has more vegetation and is relatively stabilized. Any progradation (dune development/movement through time) will most likely occur on the leeward side during periods of prevailing higher winds. That is also the side that sees the most burial as sand is moved from the windward side and redeposited on the leeward side.
If the dune is developed in an enclosed terrain such as the leeward side of a rocky cliff or canyon, it will likely not have a well developed gentler windward side slope because the winds drop their wind suspended and transported sand load in the lower pressure area below the obstruction (up wind cliff or canyon wall).
Unless a metal detectorist gets lucky and locates a recently lost item on the leeward dune face, lost items should otherwise tend to move to lower positions and become more deeply buried by subsequent sand deposition on that face.
If it was me trying to find something on the dune, I would look on the leeward dune face after a real gully washer rain storm that would have washed the sand down the dune leeward face, even as it excavated/eroded the items out of the sand. This is an interior dry land variation of the CA storm beach scarp technique. Another consideration in the foregoing is the water level/wave action along the lake/pond concentrating heavies from the toe of the leeward face of the dune. It also might be worth checking out.
 
I'm sorry , I'm still having a hard time wrapping my head around a steep 25 STORY sand dunes. Got some pics ?
 
I'm sorry , I'm still having a hard time wrapping my head around a steep 25 STORY sand dunes. Got some pics ?

Dunes all up the "coast" here, SW Michigan, East side of Lake Micihgan. some higher than 250 feet. They don't always look all that tall until you take a walk up one, like "Tower Hill" in Warren Dunes State Park, "Mount Baldy" in Indiana Dunes State Park, "Silver Lake ORV Park" or "Sleeping Bear Dunes" etc

Detecting is off limits on the actual dunes in Warren Dunes, likely same in the other parks.

This side of the lake is it's own unique "animal" in regards to sand movements.
 
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