fando

I haven't read much about the dam recently, so I browsed around and found this interesting article:

EXPOSING THE SECRETS OF THREE GORGES DAM

Here's a list of interests.

SULPHUR

Still no geophysical data has been seen. Also I would like to point out that a full scale hurricane moves alot of water

elwoodblues

Depends on your definition of 'tiny', of course, but I think it is.

Here's the best site I could find:

link

Moving mass of a spinning object from the poles towards the equator (ie, away from the axis of spin) WOULD slow down that object. Observe a spinning ice skater, extending his arms and slowing down, or drawing in his arms and speeding up. However, this effect is incredibly small. Miniscule. And, it seems, counteracted by the moon.

However, the big number here is the 10 billion metric tons. Three Gorges involves about 1 billion, so it's significant. Call it 11 billion metric tons. The earth weighs about 6 sextillion metric tons. That's a difference of something like 12 or 13 orders of magnitude (correct me if I'm wrong). The mass of water we're talking about is about a trillionth of the total mass of the earth.

There are something like 50 trillion cells in the human body. It's as if you're an ice skater, and 50 cells travelled from one part of your body to another to somehow affect your rotation. Much less than a sliver of a hair.

That matches my notion of 'tiny'.

Gurdur, I know full well you weren't necessarily putting this forward as your own idea. The 'you' was a handy way of ordering my statement; everything else sounded clumsy. You made it very clear in your post it wasn't your own ideas, and I certainly wasn't flaming you.

Gurdur

Thank goodness.

I can now reserve long sentences in upper-case lettering for Totalitarianist and Blixy Sticks.

ps418

Off-topic, and I can't remember the details right off, but I remember reading something about how glacial-interglacial cycles supposedly affected earth's rotation. At the last glacial maximum it is estimated the the volume of ice at the poles was about 50 million km3 greater than today, which is a signficant transfer of mass to the poles. That's equal to about ~1% of the ocean's water, IIRC? Not that that's comparable to the amount of water to be impounded behind 3 Gorges, of course.

Patrick

SULPHUR

The earth has natural wobble which is minutely changing the angle of the the axis all the time.There have been wobbles of various types throughout the history of the the planet. I don't think the three dam system is going to have the same effect as the two plates colliding to form the himalayas.

Starboy

Zonules, the concern for history is a hoot. Mankind builds over and destroys or abandons cities all the time. How is this any different? Life goes on. People who stop current history to preserve past history are forgetting that current events will become future history. History is history and in this case the dam doesn't diminish it one bit. After all, sometime in the dim future which site will be more historically important, just another ancient Chinese city or the great dam?

Starboy

SULPHUR

I think the initial problem was the effect on the earth. Unless the dam area has major structural geology problems it it is not going to have any major effect

echidna

Back in 1968 Egypt built the Aswan Dam which even involved moving The Temples of Abu Simbel. But entire cities, not so easy.

ps418

One of the coolest things I ever learned in geology was about the Milankovitch frequencies, how they influenced climate, and how they left a record of their passing in the ocean sediments. The axial 'wobble' is of course one of the Milankovitch cycles, and has a period of 23k years. The wobble is the reason that the axis does not point to Polaris, as it did a few thousand years ago.

An even better example may be the Permian-Triassic zenith of supercontinent Pangea, when most of the continents were clustered together in one hemisphere. That would have been a major mass imbalance, but did not seem to effect the earth's orbital geometry (as reconstructed from Perm-Triass. sediments evidencing Milankovitch cycles).

Patrick