Still with Shipwrecks, but more like archaeology, which I'll be moving the interesting facts to.

Earlier this year, they found what they are calling one of the oldest shipwrecks found to date, over 3000 years old. It was off the coast of Devon and contained copper and tin ingots. What isn't know, is if the copper and tin was coming to Britain or if it was shipping to somewhere Europe.

The copper and tin would have been used for making bronze tools, weapons and possibly jewellery.

Still on shipwrecks. I meant to write this last night, but worked late last night and was so tired by the time I got back to my flat, I just fell asleep without turning on the PC. Fortunately I had already told Nick my interesting fact for the day, just didn't have the chance to inform any on-line readers. So here goes.

There is a cargo ship in the Thames Estuary that was sunk during WW2. It was carrying supplies to the UK and held over a thousand tons of high explosives (and low explosives) when it sank. That ship and the explosives are still there and could go off at any time, as it slowly rusts on the bottom of the estuary.

The anchor broke and it initially ran aground on a sandbar. Much of the cargo was removed, before it flooded and sank.

The condition of the ship is monitored, by the Coastguard, but because of an explosion during an attempt back in the 60's to remove explosives from a similar sunken ship, it was felt to leave things as they are.

It seems that various chemical reactions between the various elements of the explosives and the metals within the ship itself, makes the left explosives more reactive.

The last thing I remember, is that if it does explode, it will generate a large wave, and the every window in the local village will be broken and many buildings will be damaged.

Still on shipwrecks, today’s interesting fact has to do with the type of ship that gets sunk. Ships made of metal, with the sole exception of possibly aluminium; do not last as long as wooden ships once they reach the bottom of the sea.

Metal ships corrode in the sea, slowly turning into one metal oxide or another. The oldest metal ships on the seabed are rusting away and may soon only be identified by rust stains on the sea bed. Even these can disappear as metal ions dissolve into the water. As the oceans absorb more carbon dioxide from the air, the sea becomes more acidic and the process will intensify.

In addition, metal ships have different types of metal in them, which sets up electrical currents between different metals and increases the oxidation.

An aluminium shell, with no other metals, will last longer, because when a layer of aluminium oxide forms on the outside of the metal, which then protects the metal underneath, preventing further oxidation. However as most boats made from this material also includes other metals, the resulting electrical current created, will cause some damage from this type of boat.

Wood on the other hand, can last millennia, especially if they get covered by sedimentation. Witness the recent discovery of a Roman boat in Germany, which has been sitting on the sea floor for over 2000 years.

At great depths and in cold environments the dissolution of metal ships may be delayed, but Titanic, sunk deep in cold water, as been shown to be rapidly rusting away.