Whay are ancient civilizations always "unearthed"?

Question

This is probably a very basic question, but why is it that digging down beneath cities reveals older cities? HOw did they get covered over in the first place?

Answer 1

Time creates different landscapes. Besides the discussion of civilizations building on top of themselves/ old cities (cultural deposition-although it is more specific than this) there are several forms of natural deposition of sediment or even soil that do not require large natural disasters. (Dirt and soil are not the same. )  While things like earthquakes and volcanoes can definitely bury a site simple deposition and time will do the same thing. There is alluvial (sediment move by water), aeolian (wind deposition) deposition, and gravitational deposition (I don't remember the cute technical name for things falling down slope/mudslides/etc.). Each of these can be further modified by vegetation, animal movement (to a lesser extent) etc. If a site has developed soil (and not just loose sediment) then archaeologists (or geologists etc.) can learn much about site deposition, (age of the site, what the site may have looked like when inhabited,  etc.) which can give insight into the inhabitants interaction with their landscape.Understanding these deposition process allow for understanding stratigraphy which is the fancy and more technical word that encompasses my previous comment about human/site interaction, site age, etc.   Wow, I feel I have run on a babbled, sorry for being convoluted.

Answer 2

It seems citied during the normal use seem to sometimes bury themselves

one example is Beth Shan,  a city in Israel near the place Saul died.  The city is built level on level on level on many many oder versions of itself

also notice in England much of Hadriean's wall is now buried underground  In that case there is nothing manmade about it,  the natural processes tending to sometimes bury things naturally  as dust blows and erossion from one place dumps material slowly to another... or sometimes very quickly

why? not sure

Answer 3

Basically as old cities, and civilizations become abandoned and "go to dust"  they are buried beneath debris. So "unearthing" them is correct because to find them and study them we must first clear all the dirt of the earth away which has covered them for centuries.

Answer 4

Cities were usually built on top of the ruins of former cities.

Ancient cities could also be covered by landslides, earthquakes, volcanic eruptions, and moving bodies of water.

Answer 5

time, weather, new vegetation,

new dirt is formed on top or sand is blown over to cover it, and at times plants grow on top,  for unearthed, but as for the new cities part, it is a solid foundation to build upon and the location must have been chosen for a good reason the first time round