Βι¶ΉΤΌΕΔ

Ancient and ArchaeologyΒ  permalink

Why dig down?

• Message 1.Β 

  Posted by Tara (U7407206) on Thursday, 22nd February 2007

  I've never understood why we have to dig down?
  Do ancient ruins and artifacts sink or do they get covered by dust ect
  Does this happen at different rates in different places?

  Link to this forum: Why dig down?

  Report message1

• Message 2

  , in reply to message 1.

  Posted by Stoggler (U1647829) on Thursday, 22nd February 2007

  The reason why is because soil accumulates over time; it is the combination of mineral and organic matter and forms from the combination of physical, chemical, and biological process.
  
  Check out Wiki for a better explanation than I can give:
  
  
  
  
  It really struck me how much soil can accumulate over time when I visited the Roman villa at Bignor in Sussex. There's one mosaic where you're standing on a platform about one foot or so above the mosaic itself (which would have been floor level in Roman times), and there's a window next to you and through the window you can see the modern day surface level, which was level with my head. So that's about 7 feet in depth of soil accumulation in 1500 years or so. Not bad going!
  
  Again, I don't know any details but I'm sure that pedogenesis (the formation of soil) does vary from location to location, based on the soil type already there, the underlying geology, the flora, climate. And in some cases ruins and artefacts may sink if the underlying soil or geology is unstable (or it just slowly sinks itself over time, as can be seen at the Fishbourne Roman Palace where the famous mosaic of the boy on a dolphin is sunken in the middle) but essentially the reason why we have to dig in the first place is because of the buildup of soil over time.

  Link to this forum: Why dig down?

  Report message2

• Message 3

  , in reply to message 2.

  Posted by U2280797 (U2280797) on Thursday, 22nd February 2007

  If your wife made you sweep up leaves every year you'd not find this a bit baffling - and leafmould makes an excellent soil.

  Link to this forum: Why dig down?

  Report message3

• Message 4

  , in reply to message 3.

  Posted by DL (U1683040) on Thursday, 22nd February 2007

  "Why dig down?"
  
  Because digging upwards isn't very productive??
  
  Sorry, couldn't resist.

  Link to this forum: Why dig down?

  Report message4

• Message 5

  , in reply to message 2.

  Posted by Tara (U7407206) on Thursday, 22nd February 2007

  Thanks for that, It does make sense.
  The comments about digging upwards still has us laughing.
  However I must correct the comment about my wife making me sweep up leaves!
  1 As a women I dont have a wife, but I can see how useful it could be
  2. I've found that leaving the leaves cos they either blow away or disintergrate
  LOL

  Link to this forum: Why dig down?

  Report message5

• Message 6

  , in reply to message 1.

  Posted by TwinProbe (U4077936) on Thursday, 22nd February 2007

  Hi Autumn,
  
  This question crops up periodically, and I think must be a general puzzle. A great deal depends on where in the world you are, of course. In hot, dry areas like North Africa Roman remains may well still be on the surface (if they've escaped the odd sandstorm).
  
  Things are very different in Britain. As has been said the accumulation of organic material, like leaves, and the action of the earth worm tends to cover building foundations with soil in a century or two. This process occurred in antiquity as well, so it is not uncommon to find the remains of, say, one Roman villa built on top of an earlier, with perhaps an Iron Age round house under both.
  
  On well draining hill-top sites Roman remains may be just under the ploughsoil - and indeed are commonly damaged by the modern deep plough. Wet soil tends to move slowly downhill (colluvial flow) and therefore valley bottom sites have a thicker depth of soil as cover for any archaeology.
  
  In a wet UK urban site, York is the one I know best, things are very different again. Century after century organic materials have been imported into the city in vast quantities. Examples of these materials are wood, animal carcases, foodstuffs, thatch - and human beings that ultimately become dead bodies. The organic material survives very well in waterlogged soil and accumulates in the form of middens, cess pits, cemeteries, rubbish heaps, and so forth. Inexorably the soil level rises.
  
  Common practice seems to have been to remove those parts of a decaying building that were above ground, cover the site with soil or rubble and build again. The process went on century after century and the earliest structural remains may now be 3m deep or more.
  
  In parts of the world where building in sun dried mud brick was common the buildings returned to mud eventually (perhaps after rain) and further sun baked mud brick constructions were placed on top, only to decay in their turn. By this means, over thousands of years, large occupation mounds or tels were created.
  
  Regards TP

  Link to this forum: Why dig down?

  Report message6

• Message 7

  , in reply to message 5.

  Posted by U2280797 (U2280797) on Sunday, 25th February 2007

  Autumn - Sorry about the gender mistake. Obviously your leaves are blowing into my garden. Please come and take them back.

  Link to this forum: Why dig down?

  Report message7

Back to top