Why do archaeologists have to dig?

Question

Ok, this is a serious question. I feel ashamed not to know the answers, but I never understood this.

I was standing in an early medieval church in Ireland a few years back. It had been excavated and its ground floor was now at least a meter below ground. How did it get there?

I don’t understand the process, of how pottery, churches, spearheads, streets or dinosaur bones for that matter, disappear below ground. I know that the ground consists of layers, and that geologists can determine the date of a find, by looking at the layer it comes from. But how are these layers formed? I don’t suppose the earth got any bigger? Where did the ground on top of these finds come from? How does the earth burry its own history?

Now I know that floods, wind and volcanic activity can shift soil and leave deposits, but surely that cannot account for all of this. And then how is it possible that in Australia the remains of pre-historic campfires can still be found on the surface?

Thanks!

Answer 1

well you basically answered your own question. winds and rain are most of the reason. lets say an animal dies it falls on the ground and decomposes until nothing is left but bones. over time wind blows and covers a little bit of dirt not much just enought to maybe cover 1/2 inch. then it rains and the soil turns to mud the bones sink a little maybe a full inch. then the wind starts to blow again covering another 1/2 inch, then it rains again and so on and so forth. now multiply that by a couple of million years

Answer 2

Archaeological artifcacts become buried under debris caused by changes in the weather, just as you mentioned, (wind, rain, volcanoes and also earthquakes) Eventually, pottery, metals, bones etc, return to the earth and need to be dug up in order to study.

As for Australia, there are still primitive tribes inhabiting the outlands and surviving much the way their pre historic ancestors did.

Answer 3

The dirt accumulates in a number of different ways, such as by flooding and blowing dust. Given enough time, it can become arbitrarily deep.