Maybe calcium carbonate lends itself to big scale mounds because it is easier to pile up than other stone nearby? Both easier to split and easier to carry than say, the silicone solidity of sarsen? For some reason I'd always assumed the pyramids were sandstone, with only the outside having been limestone.

http://www.touregypt.net/featurestories/giza.htm
reckons the core was limestone too. Also that "kher neter" means "the necropolis".

Forgive my schoolboy geology but isn't calcium carbonate just chalk which in turn is just a very fine grained limestone which is a term applied to any sedimentary rock consisting of carbonates.
I reckon if you took a poll of the geological composition of most of the great monuments & buildings of the world, you would find a great proportion of them to be built of these materials.
As for the fertile region- A greater proportion of the monuments in the above poll would be built in a 'fertile region' with some name eluding to that fact.

Finally, it's not very polite to start a brand new thread with a personal attack on a fellow contributor.
Etiquette demands that you allow them to make the first move before letting the vitriol flow.

Carboniferous stones come in a wide variety of forms: compact, crystalline, crynoidal, oolitic, pisolite, reef, and metamorphosed (marble), all with quite different properties from a constructional point of view.

The core of the Giza pyramids is made from oolitic limestone quarried nearby on the plateau. The rock comprises oolites (the shells or fossilised remains of small sea creatures) bound together by clay. The quality varies considerably across the plateau with some areas being so marly that the rock is crumbly and easily eroded by rainfall. The outer casing stones were made from fine white Tura limestone from across the Nile.

I think its unwise to claim any association between Silbury and the pyramids based on the materials used, since in both cases the builders used the most readily available materials at their respective sites.

Furthermore, the statistical significance in the agreement of a single number like five is virtually nil. It's probably more significant that it happens to be the number of fingers and thumbs on one hand.

Building a monument out of your local rock doesn't seem like a coincidence at all to me.

As I understand it, Silbury is built on a spur of chalk sticking out in the fertile flood plain so doesn't represent an intention to sacrifice good land, quite the reverse.

The connection between c*nt and fertile place..... now THAT seems like mere coincidence, stretched beyond reason, one being biology and one being geography.

The only matter yet to be resolved as being a coincidence or otherwise is why aggressive or trolly postings always get posted between 10.00 and 11.00pm at night. I wish they weren't.