There is, of course, the moisture content of soils to take too account. The liquification of soils is likely to reduce its ability to support heavy loads and therefore produce the necessary environment for sinkage.
On the subject of earthquakes, there is also a related phenomenon whereby the intense vibration of the quake causes the fabric of certain sedimentary rocks to temporarily 'liquify' as it takes on a plastic state. This is often the cause behind buildings and other manmade structures to sink in earthquake environments.
Sent from my Samsung Galaxy smartphone.-------- Original message --------From: Michael <[log in to unmask]> Date: 2017/02/22 09:20 (GMT+00:00) To: [log in to unmask] Subject: Re: [BRITARCH] Why archaeology gets buried - the Caterpillar effect
I'm convinced that whatever the reason, when viewed over very long
time-scales the top soil is more like quicksand than something firm.
If biological - it will no doubt depend on oxygen in some way - so must
decrease with depth
If mechanical from heat/cooling likewise
if mechanical from increase/decrease in water - the effect is likewise
greatest at the surface
If mechanical from periodic earthquakes (and we get a surprising number
of small ones in the UK) the rate of sinking will be uniform until any
object hits the bedrock.
Do you know of any work on rate of initial burial of finds. Relating
depth of burial, soil type, (I presume also artefact density) and length
of time at the site?
On 22/02/2017 09:02, Vince Russett wrote:
> Hi folks
> Yes, of course what I wrote was incredibly simplified (well, it was early
> in the morning!) and there are many other factors such as ploughing and
> colluviation in general, spreading of imported material in towns to level
> sites for construction (or indeed, to make gardens) - as John said -
> wind-blown soil, dust and sand, growth of surface lichens, then grasses to
> cover inert substrates, such as rock and so on.
> Although we always quote earthworms as the main generator of soils (Mr
> Darwin put us onto this one!), soil is generally an insanely complex
> ecosystem, which tends towards increase in bulk, except when agriculture
> and other disturbances interfere. There are many other micro- and
> macro-organisms that help to develop soils. If you want to see that in
> action, bring a couple of tablespoonfuls of garden soil in and look at them
> under a microscope. You will, I'm sure, be reminded that
> 'Great fleas have little fleas, upon their backs to bite 'em,
> And little fleas have lesser fleas, and so ad infinitum'