What are those notches for?
According to Wikipedia, the notches are for stringing barbed wire.
And what about the concrete blocks ?
Better answer, The notches are for attaching the concrete blocks to…
The photo shows them places in the shallows, where waves would knock them around … they had to be weighed down with concrete …
Must have been hell for France to clean up and remove all this stuff after the war, plus landmines.
The hedgehog obstacles at Normandy were originally emplaced in prewar Czech. Rommel had them relocated to Normandy. As these were designed to be land obstacles, the concrete feet were needed to keep them stationary in the water. But these feet were an afterthought after they were transferred from their original location and purpose. The land based tschechenigels never had concrete feet, but they always had notches.
Landmines are hell everywhere. As a teenager in the 50s I spent a happy summer volunteering as part of something called The Civic Trust, to clear up beach defences on South Coast beaches. Mostly steel and barbed wire but we did get to blow up some concrete bunkers. No landmines though.
They fed and housed (mostly in tents) us and we put in eight hours of hard work.
So they were still cleaning up beaches in the 1950’s? I wonder when they could finally declare France “landmine free”?
If you visit any European beach that might have been subject to invasion by the enemy, you will still find the almost indestructible remnants of the defences. In Normandy there is a whole tourist industry around them.
Even apart from the beaches there were two other lines of defence in England should the Germans have actually landed. Even today, these “pill boxes” as they are know (from their shape) can still be seen at strategic points in the hedges on country lanes in the South.
Mine free or shell free ?
As I understand there are still removing World War 1 shells form many battlefields. Full time crews doing this.
“Battlefields” has a pretty loose definition, given that aerial bombardment dropped bombs all over the place, including in cities. I saw a documentary not long ago in which a crew was replacing a section of tarmac at Frankfurt airport. The project was time-sensitive, and they were concerned about the possibility of unearthing unexploded ordnance; had this happened, an EOD team would have been called to remove it, which would have delayed the project.
See https://en.wikipedia.org/wiki/Unexploded_ordnance for more which indicates the French government pulls up about 900 tons of unexploded ordnance, including landmines, per year. That’s just under 3 tons per day, day in and day out, year after year.
Wiki also says the German authorities find & deal with about 15 items per day, mostly aerial bombs.
Sometime in the last year I read a dead-tree magazine article about the German federal agency that does this work. They believe they have about a century’s worth of work ahead of them at the current rate of recovery. This is assuming they can go a whole century without somebody having a war or revolution on their soil. Which sadly enough, given human nature, cannot be guaranteed.