Written by the Treasureguide for the exclusive use of the Treasure Beaches Report.
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| Family Photo Found 130 Miles From Home After Tornado. Source: See AP News link below. |
When Katie Posten walked outside Saturday morning to her car parked in her driveway, she saw something that looked like a note or receipt stuck to the windshield.
She grabbed it and saw it was a black and white photo of a woman in a striped sundress and headscarf holding a little boy in her lap. On the back, written in cursive, it said, “Gertie Swatzell & J.D. Swatzell 1942.” A few hours later, Posten would discover that the photo had made quite a journey - almost 130 miles (209 kilometers) on the back of monstrous winds...
Here is the link for more about that.
Photo from tornado-damaged home lands almost 130 miles away | AP News
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Yesterday I mentioned that wave tanks are not realistic in many ways. They can be useful, but also misleading.
If you take a look at the video linked below, you'll see a number of things that make it act unlike a natural beach. In this case, it is very easy to see some of those. First might be the narrowly directed focus of the wave tank waves. They can not spread out, and the there is a hard bottom and slope, which is very unlike a real sand beach.
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On a beach, unlike in the wave tank, there will be a primary and secondary swell. Waves coming from different directions interact. You can easily see that in the field.
In a wave tank, there are no tides. The water level remains constant. The generated waves continually bang away at the same high water mark.
See Wave tank demonstration showing the impact of coastal defences on flood risk - Bing video, for example.
The waves in a wave tank have a set period - seldom changing. The waves come at one-second, ten-second, or whatever intervals. The period of the wave makes a difference. In fact the wave period has a lot to do with erosion. I haven't studied that enough.
Small waves with a short period interact. A new wave coming in will hit a returning wave before it toes very far. That neutralizes the force of both waves.
If you've ever watched what goes on in the swash at the bottom of a beach when the summer waves are particularly small, you would see that easily moved shells such as olive shells will repeatedly move an inch or so in one direction and then back with the cominag and going of each wave and show no significant net movement in either direction.
One of the things I've not emphasized much in the past, is the importance of the slope of the beach. Since it is the returning or outgoing wave that carries sand away, the speed or force of those waveshas a lot to do with the amount of erosion that occurrs. If the slope is steeper (other things being constant and they never are) the returning water will have more speed and force and tend to carry more sand and other objects. During a small summer surf you'll see the water run up the slope and then disappear into the sand rather than returning down the beach with any force. And sand that was suspended will be dropped and added to the beach.
Sand can be loose or compact. That makes a difference too. I've never seen that discussed as it relates to erosion. When there is enough flow reaching the dry sand, loose sand will be washed away more easily than packed sand.
The most important thing I've discussed is the amount of force required to pick up or suspend sand and other objects and the amount of force required to keep various items moving. The difference between the force required to keep move and keep various items moving is very important in determining where they will end up. I've talked about coin lines, which are formed when the flow decreased at a location and drops of coins. As I've described before, you'll often see that quarters are lower than zinc pennies, which will often be higher in the line. Coin lines can be thick or narrow, and you'll see the result of categorization or sifting within the line.
Although I've talked a lot about angles and how important they can be in determining erosion, I've not talked enough about invisible features that like reefs that affect the shape of the beach as well as the location of erosion.
It looks like Wednesday the surf will be bigger. It will be up to four to seven feet, which is enough to possibly cause some significant erosion - depending, as I've been describing upon a number of factors.
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| Source: MagicSeaWeed.com. |
Unfortunately, the peak will not last long and the tides are not big, so there are two important factors that will not work in our favor. If there is any significant erosion, it will not be huge and it will not be widespread. Productive areas will be few. The productive areas will most likely be those where the beach has previously been reduced in recent weeks, even though the location has refilled since the last erosion event. While the surf is predicted to reduce a touch after Wednesday, there are supposed to be a few more days of four to six feet to follow.
Happy hunting,
TreasureGuide@comcast.net
Pray for tornado victims.