Tag Archives: long time

The earth formed from an accretion disk which collapsed to rings and then further collapsed into planets. This happened over a very long time and involved different lumps of matter colliding with other lumps and breaking apart before finally forming the planet. Think for a moment – the materials in the orbital plane will be everything from hydrogen to most of the heavier elements in varying quantities (eg, there is very little Francium, but lots of silicon). Anything heavier than iron in fact has come from a stellar explosion somewhere and some time in the past. Elements from iron and upwards are formed in these explosions – the only way they are made in fact – and flung at enormous velocities into space in all directions. They are fragmentary or mere atoms in most instances.

So, round and around the rings in the accretion disk go, being nudged and bumping into each other, and slowly increasing in mass until we have a reasonably circular planet. Over time we get some asteroid impacts; comets crash and give us oceans.

Then there are plate tectonics, where surface material is dragged under a plate and then compressed, and mixed around, while at the same time we are returned new rock/material in the form of either volcanoes or rock simply oozing out of another plate joint. This has been going on for a very long time – my guess would be over 3 billion years. Super-continents have come and gone; the Pangea’s, Rodina’s, etc. They are banged together and broken up in a never ending cycle.

During all this time rocks and deposits have been sucked underground to the depth where rock is almost liquid and has very odd properties. Nothing escapes. Continents continue to be ripped apart and smashed together – over geological ages. Why, with all the
- mixing in the accretion disk,
- followed by mixing through the planet forming process
- and then more mixing through the plate tectonic process
do we have concentrations of any elements anywhere?

All the time, old rock is sucked away and replaced by new rock. A geology site I saw said it takes 100 million years (as a rough guide) as the time it takes for rock to be sucked in, mixed about with lots of pressure and heat, and then spewed out as new rock … only to become old rock, and sucked away again … over and over and …

Think of diamonds in Russia and South Africa, emeralds down the skull coast (?), uranium in some places, copper in Chile, and so on (yes, diamonds are a bad example). I would have thought that all the mixing which occurs prior to, and during planet formation, and then subsequent mixings would leave no concentrations of anything; rather, some homogeneous stuff with unknown properties (unknown to me, that is). Every piece of earth has been through the plate-tectonic ‘sucking-under’ process about 40-50 times, so it ought to be really mixed up. I would expect that we had no concentrations of any element, but if you picked up a cup “stuff”, it would contain all the elements in a similar ratio to how they are formed in nature. (For instance, you know more iron will form in a supernova than say Iridium, which is scarce by comparison).

Therefore, my question is summarised as “Why are there concentrations of minerals in certain places, instead of a consistent mixture of everything, everywhere?”.

(Being creative, we would know it would be slightly magnetic, slightly radioactive, highly poisonous … etc. An interesting exercise in itself).
Gee XroZebo, do you masterbate in public as well?