Archaeology - I don't get it.

If you dig down a few feet you find artifacts from medieval times, go down a few feet further and you find yourself in the Roman era, keep going and you’ll be in the Bronze age.

If you go down maybe 10/15 feet you find objects from pre-historic times.

Doesn’t this mean that the diameter of the Earth was 10/15 feet smaller in pre-historic times than it is now?

That in 3000 years or so, everything that is on the surface of the planet now will be under a further 10/15 foot layer of dirt?

Where does all this extra dirt come from?

Is the planet bigger now than it was in prehistoric times?

Is it going to keep on getting bigger?

I just don’t get it.

It’s not new dirt, it’s shifted dirt. Moved by wind and rain.

Sounds like there should be a law that covers this. Dirtropy or something like that.

Sounds somewhat like my cleaning method.

OK, we have two factors here. Deposition and erosion. Dirt is deposited by wind and water but also eroded by wind and water. So the dirt that fills up the valleys comes from the mountains. So why do we still have mountains? Well, volcanoes and shifting plates lift up the mountains. And you can get alternating periods of deposition and erosion in one location.

Another major depositor of material for archeological sites is humans. If a village has been inhabited for thousands of years, then you have thousands of years of garbage piling up. Many ancient villages in the middle east are now built on hills, after thousands of years of collapsed mud brick buildings.

Keep in mind that while some places accumulate new layers, other areas are losing layers. If you dig down under my house you will hit extremely old granite in a few feet. The former top layers of soil that date from even 1 million years ago are long gone (where they covered up artifacts some place else).

Also, worms and other dirt critters continually move soil up while leaving rocks and such behind. (But frost heave works the other way.)

FtG

Also in some places the land is still rising again after being pushed down by glaciers during the ice-age.

It’s a side point, but I though I should mention that the earth is “struck” by many tons of space dust and rock each year. Most of it burns up on its trip through the atmosphere, but nonetheless, the mass is added to the mass of the earth.

So the earth does get bigger by a relatively tiny amount, but it has nothing to do with the burying of artifacts.

Soil is created through the pedogenic process, which is the transformation of surface geologic materials through chemical, physical and geologic processes. The amount and type of soils created will depend on five factors:
[ul]
[li]parent material[/li][li]climate[/li][li]topography[/li][li]organisms[/li][li]time[/li][/ul]

So in an area with lots of organisms, lots of parent material (rocks that are decomposing, sediment deposits, alluvial deposits, etc.), a condusive climate, and lots of time, you’re going to get a lot of soil created. Ok, so it’ll take a long time, but we’re thinking geologically here.

Dirt is constantly being transported hither and yon, so with these pedogenic processes going on, you’re not getting huge influxes of soil just in one place. So yeah, the planet is growing I’m sure, but not all at once, and not as dramatically as you’d think.

Heh, haven’t put my archaeology degree to use in a while. Thanks.

Is it true about what the creationists say about artifacts being found on mountain tops? If it is, what other ways could they have got there other than the fabled flood?

Speaker, I’m not sure what you mean by “what the creationists say”, but sure, artifacts have been found on mountaintops. How they got there is probably the same way people get there today–walking or climbing to the summit. Human burials have been found there as well. Mountaintop climates (like peat bogs) are very good from a preservation standpoint.

If you have some specific examples, I’d be glad to try to answer more questions about them.

Remember the Ice Man. He was very well preserved as were his accessories which included straw stuffed shoes and birch bark container. Deserts are also great climates for preservation.

I thought the whole thing with creationists and mountain tops was about seashells; “how else could they have got there if not a global flood?” - entirely (and possibly deliberately) missing the point that mountains weren’t always mountains.

The question seems to have been answered satifactorily. Movement of dirt. Some places are losing dirt like the Apalachians, others are gaining dirt like the Gulf of Mexico. This is why if you’re looking for 80 million year old soil you can’t just go anywhere you have to go to specific places that have soil that old in other places it has been lost by being washed away.

Anyway the real reason I’m here is to say that the OP is right the Earth is gaining mass as it has been since the very beginning as asteroids, comets and other space dust fall into our gravity well. But this growth is imperceptible. I can’t tell you how fast this is going on since theories about how often we are hit varies considerably but it’s there and certain, just very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very very slowly.

I vaguely remember seeing somethign simliar before, but don’t remember the results really… Do some atmospheric gases leave the atmosphere and venture into space? If so, how does the mass of such gases compare to the accumulated mass of asteroids hitting the earth? Still gaining mass? Ultimately losing mass? Pretty much the same?

Mostly it’s just hydrogen that escapes which is of course very very light. The lightest thing there is. Element wise. I’m sure it works out that more then a ton in mass is acrued by the earth over a year. Although the earth weighs 6,580,000,000,000,000,000,000 tons. So if we acrued a ton a year ever since the dinosaurs died that would be 65,000,000 tons which is what? about 0.000000000000987% We’re simply so huge it’s not noticible.

Note: we do not gain 1 ton a year, it was merely an example as like I said estimates vary.

Sea shells found in the Andes are seen as evidence of massive meteor strikes into the Pacific Ocean, which cast the sea shells into the air, and which landed on the tops of the mountains.

Yeah yeah, I was trying to remember his name, Otzi or something like that. I’m currently watching a special on Nova on the 2400 yr old mummies that Russian archaeologists found in Siberia. Oh my GOD is the preservation amazing. The female mummy was so well preserved you could see her facial features and tattoos, and her clothing was completely intact. Gave me the shivers.

Mangetout covered the shells on mountains thing; so I’ll just toss my agreement in with what he said.

Mangetout and Dave Stewart covered it, I should say. Sorry bout that.