Re: What substances can I use to make a clay matrix for a small archeology dig

Great!  Well, the Tate Museum in Casper, WY has been making "fossil digs" 
for the past several years.  I have to say I have run several quarries 
around Wyoming and I have to say these things are a blast even for the 
trained paleontologist!  Ok, the directions are relatively simple.

  Get a tray (disposable) of the size needed to bury the materials to be 
dug up.  You will need these supplies.

*  Tray (disposable)
*  Plaster (of Paris)
*  Mixing container/stir stick (disposable)
*  Cement powder dyes (optional)
*  Materials to be buried
*  Trash bag

To begin with put a trash bag on whatever surface you are going to prepare 
your "dig" on.  Then mix a small quantity of plaster (directions will be 
on the box, you want a semi-thick mixture) in the mix container, add a 
pigment if you want (ultimately this will appear as differing "strata").  
Pour in about a 1/6th -1/4 of your plaster into the dig tray.  Place 
materials that should be "discovered" in that area.  Then repeat the 
mixtures of plaster (alternating colors of pigment), adding successive 
layers with specific material in each layer.  
    Most sites, either archeological or paleontological are considered to 
be stratified.  In fossil sites there are often different species in the 
different layers (e.g. you wouldn't find a dinosaur with a sabre-toothed 
cat).  Archeological sites are similar.  You can have various people 
inhabiting the same area but in different times, and each group will leave 
something a little bit different.  You can represent this stratification 
by layering your material between each pouring of plaster.  
     Once all of your layers have been built then let the plaster set up.  
This can take up to two days, depending on the "wetness" of the plaster.  
You will no it is done when it no longer feels damp.  

      You can use all sorts of tools to "prep" the dig.  If allowed, visit 
your local dentist and ask for an old dental pick for use as a dig tool, 
it is what paleontologists really use.  Or you can make do with a nail, or 
even toothpicks.  Have fun on your dig(s).  Maybe while you are making one 
for yourself you can make one for one of your teachers.  It can be a very 
useful tool when discussing geological time, and paleo/archeology.  

Cheers