10,000 Year Old Concrete in Polynesia

a reply to: Violater1

I haven't heard of that before.

Limestone is natural concrete. Sandstone is natural concrete. A coral reef is composed of natural concrete.

I can see a concrete gear housing. I can see where the two narrow shafts come together at a 90 degree angle.

I can't. Even if I squint.

originally posted by: Phage
a reply to: Violater1

I haven't heard of that before.

Limestone is natural concrete. Sandstone is natural concrete. A coral reef is composed of natural concrete.

I can see a concrete gear housing. I can see where the two narrow shafts come together at a 90 degree angle.

I can't. Even if I squint.

Limestone, and Sandstone are natural concrete?
Really?
Really!
Please tell us what nature uses as the cement for concrete?

a reply to: Violater1

Please tell us what nature uses as the cement for concrete?

It varies. Silica, calcite, clay.

Durability of sandstones is determined not by the hardness or chemical stability of the major constituent (quartz grains), but by the cementing agent which binds them. The cementing mineral is used as a sliding-scale durability measure, with siliceous as most durable, followed by calcareous (calcite being the mineral binder), ferruginous (iron oxide) and at least durable argillaceous (clay binder).

www.sciencedirect.com...

originally posted by: Violater1

originally posted by: Phage
a reply to: Violater1

I haven't heard of that before.

Limestone is natural concrete. Sandstone is natural concrete. A coral reef is composed of natural concrete.

I can see a concrete gear housing. I can see where the two narrow shafts come together at a 90 degree angle.

I can't. Even if I squint.

Limestone, and Sandstone are natural concrete?

Really?
Really!
Please tell us what nature uses as the cement for concrete?

Happens all the time portlandite comes to mind for example. Yes, concrete can be naturally occurring in fact it been known to find things like spark plugs shovels, etc encased in concrete. the process can happen very quickly. My bet is this island has a very high alkaline content in the water. It makes more sense than a civilization 10000 years ago who thought cement could only be used to put a pole in the ground. If a civilization figures out about concrete it would quickly be used to build walls and floors or even aqueducts.

a reply to: dragonridr

The Coso Geode was a Concretion not actually naturally occurring Concrete, the substance was quite different to concrete and mistake for a natural rock but was baked onto the old Champion Spark plug (Circa 1920's) by the sun so actually baked on mud probably from a brook, that said the shovel sound's suspicious, a shovel is often used around concrete so how can that be known to be natural but you are correct Natural concrete does occur, some of it far better quality than we make use of in our construction.

It does however require very strange and unlikely conditions to be met, mixing strata of rock's some containing the matrix such as gravel and sand bearing layers and others with the limestone - to make it really concrete this natural occurrence has to then be heated to a high enough temperature to turn the lime stone into quick lime and to have water to allow the chemical reaction to take place, this is however made easier once you consider that natural concretes which have been found (and assumed to be natural concretes since there is no other plausible - to the current view of prehistory) have a long time to form.

However typically speaking concrete is actually unlikely to form naturally, it can and does however the earth has heat, water, geological stratification and faulting which can all contribute to allow this to occur, strange then that so little of the so called naturally forming concrete has formed in these conditions which of course then raises the eyebrow a little now does it not.

And remember that it is only an interpretation when this material is found if it is too old to be attributed to the KNOWN timeline of humanity for it to then be regarded (by opinion) as a naturally formed concrete.

But given time and pressure all strata are made into stone, clay is already stone as is sand, put either of these under enough pressure and they will turn back into a solid mass of stone, sandstone in the case of buried deserts, sea bed's and river sediment's though river sedimentation can also mix the correct ingredients to create natural concrete but not the conditions, if it is solidified because it is buried it has to be be buried under enough pressure (depth and therefore great age) to be pressed into a solid mass, is this still concrete though even if the same ingredients are present or is it just an analogue of concrete since it is hardened by pressure rather than the chemical reaction which hardened GENUINE concrete and cement.

So how old was that shovel again?, or was it artificial concrete perhaps quick lime on the shovel bonding with other materials in the matrix of material that it was buried in?, even that sound's implausible however since any workman worth his salt would not leave his shovel like that, he may lose one on a construction site however - could an ancient builder have done that only for someone to claim his shovel was contemporary to there time period when it became inconceivable to them that such could be the case.

However there are some interesting cases of petrification, not quite the same thing but close.
This is far from the only example of mineral rich water encasing objects.

originally posted by: Phage
a reply to: Violater1

I haven't heard of that before.

Limestone is natural concrete. Sandstone is natural concrete. A coral reef is composed of natural concrete.

I can see a concrete gear housing. I can see where the two narrow shafts come together at a 90 degree angle.

I can't. Even if I squint.

Essan a good fellow on another board posted this paper.

core.ac.uk...

a reply to: Hanslune

That place is pretty old. Lava and sedimentation of various types builds up in the Melanesia Trench, for a long time. From underwater it is then thrust to elevations of 1,300m. It then erodes for a while, while subsiding about 200m.Then it rises again, a little.

Fossil corals, basalts, sandstone.

Complicated. Someone who knows their stuff should have a look at the site. A geologist, I would expect.

originally posted by: Phage
a reply to: Hanslune

That place is pretty old. Lava and sedimentation of various types builds up in the Melanesia Trench, for a long time. From underwater it is then thrust to elevations of 1,300m. It then erodes for a while, while subsiding about 200m.Then it rises again, a little.

Fossil corals, basalts, sandstone.

Complicated. Someone who knows their stuff should have a look at the site. A geologist, I would expect.

Very complicated indeed! Yeah they need a geologist - oh actually a geochemical (chemical geology) engineer might be better
en.wikipedia.org...