Monday, September 28, 2015

9/28/15 Report - Surge and Backwash and Cut Beach. Tropical Depression Eleven. Higher Waves.

Written by the TreasureGuide for the exclusive use of

Illustration Showing Surge and Backwash On A Beach With A Cut
A few days ago I presented a couple of illustrations to show how coin lines were formed.   My intention was to continue on that subject, but I got on some other subjects.

The illustration in the previous post showed how the surge went up the slope and gradually decreased and then washed back down the hill.  When there is a cut, the surge can hit the face of the cut before the water slows.  When that happens the surge bounces off of the cut and washes back down the slope with greater force than if it had gradually slowed down on the slope.

The tide is important.  When a cut is created before high tide, as the tide increases, more and more water hits the cut as the tide comes in.  When the tide starts to go down, and if the waves are not big enough, the water will no longer be hitting the cut at all.

If the cut is created at low tide, the high tide can over-wash the cut and smooth it out if the water is hitting the beach straight on.

The main thing to notice is that when the water continues to hit a cut with force there is no gradual slowing of water as the surge slows and reverses.  Instead the water can hit the cut with force and bounce back sending the water back down the slope with force.

When the waves are hitting straight on, the backwash will be colliding with new surges.  If the wave period is small, that will happen frequently.

When the surge and backwash collides there will be a reduction in force at that point, and items can be dropped off.

Any items washing out of the cliff can be temporarily covered and protected by sand eroded from the cliff.

If the water is hitting at a angle from the north, then the water can wash up onto the beach and curve back down without losing as much force.  That can move a lot of sand and other items.  Of course if it is coming in at a good angle it can still carve away at the cut when the water is high enough.  You get more erosion when there is a good angle and high water.

High water washing directly up the beach will not cause nearly as much erosion as water washing in at an angle.


Treasure Coast Beach This Afternoon

Last night we had a super moon and a lunar eclipse.  The tides were high, and I hear that in some areas there was flooding.  On the Treasure Coast the tide was about two feet higher than normal.  I didn't see any type of flooding.  In fact I thought the water was not any higher than yesterday.

Ida has finally disappeared.  We have Tropical Depression Eleven to the east of the Bahamas.  I expect it to stay out there and move north and not affect us much.  The waves were bigger though.  I thought in some places they looked like six to seven feet.  I saw a few surfers.

I found one cut that was close to two feet high.  I'm sure there were others around the Treasure Coast. I only looked at a couple of beaches.  One was mushy.  The other wasn't.

I wasn't finding anything old where I was.

There were some shells and fossil pieces.

We also have a disturbance in the Gulf.

The surf is supposed to be 3 to 5 feet until Wednesday when it is supposed to be up to 6 feet.

You might be able to find a good cut somewhere.  The waves are hitting directly from the East though.


The history of money diggers article that I presented yesterday is a good read.  You might be able to pick up a few good clues from it.  In any case the folklore and history is interesting enough by itself.

Also check out the bibliography at the end.


Happy hunting,