archealogical digs

[fly258]

when on a dig , how did the artifacts come to get covered in so much earth

[jno]

In pretty much the same way my floor gets covered in dust, only there's more of it because digs tend to be outdoors and dust, dirt, rain and so forth land on them  for centuries - and then maybe other civilisations come and go on top of it all, so you get crumbling buildings and rubbish all piling up and decaying...

It's not always like that; in the desert, for instance, you may come across long-dead caravan cities where artifacts are just lying on the ground waiting to be picked up.

[Marsh]

Even in deserts the sand drifts and covers things � check out Francis Frith's 1898 photo of the sphinx on http://www.geh.org/fm/frith/htmlsrc/frith_sld00001.html   (If you get "Page cannot be found" the gremlins have probably added a <P> to the address � delete it and try again).
In England worms cause boulders to sink.  They travel under rocks and then bring the earth up to the surface.  The worm casts slowly build up round the boulders, the earth recompacts beneath and the boulders disappear.  This is in the book that Charles Darwin wrote about earthworms (yes, that Charles Darwin).  I don't see why it shouldn't apply to smaller objects as well as all the things that jno mentioned

[cassimer]

Archaeologists call this stratigraphy - the layers of deposition that cover objects. In reality a lot of objects that we recover today were deliberately buried - burial goods, hoards etc. Another large source of artefacts is rubbish dumps which are filled in by hand and naturally over the ages- pottery is virtually indestructable so broken bits survive, as do some bones or wooden objects if the conditions are right.
Walls and foundations (think time team) survive as over time, particularly in towns the street levels rise due to the accumulation of dirt, the laying of new surfaces etc which significantly altars the ground level.
Natural land movements such as landslides and building collapses preserve a lot of material which we now uncover, famously in pompeii form the volcanic ash.
Other ways of getting buried are more simple - a labourer working in a field might drop a coin, which is hard to find, and would get worked into the soil.
Any bits of interest such as precious metals or weapons, and anything of value would not be left where possible, so the artefacts buried now are either religious context, or not worth keeping in antiquity.