"Dig your own fossil" kits have been around for ages. It’s always fun to chip away at dirt/clay/rock to find some sort of treasure inside. I’m sure many a geekkid (young and old) have blasted through a few. They are good for a few minutes of diversion, but they also mostly have an unsatisfying payoff (although I recently found these, and my 4-year-old was giddy at his full, 3D stegosaurus skeleton).
The trouble with many of these kits, beyond the lame toy at the end, is that they are short-lived. Dig for ten minutes and you’re done. So, what’s an intrepid geekdad to do? Why, make your own bigger and better, of course!
Here is a great summertime project that gets the geekkids involved. It’s messy, physical, and has a great payoff. Some amount of experimentation might be needed to find the optimal mix for your matrix, but the following should be good to get you started making your own fossil fields.
Plaster of paris
An equal amount of dirt, rock, and sand (for realism, naturally)
A small, shoebox sized plastic storage bin, or foil baking pan.
Plastic dinosaurs, shells, or other diggable treasures
A bucket for mixing
A large stick and garden trowel for stirring
A nice day
Material to water ratio is 2:1. Mix your plaster and dirt together in the bucket and add water a little at a time. Mix with your stick and keep mixing until you get good creamy mud. (Here is where the geeklets get a workout!) Pour in a layer of mixture into your mold. Add your "fossils," add a layer of mixture. Repeat in layers until you fill your mold.
The mixture will harden quickly, but will still feel wet. Digging takes a bit of effort, so have hammers, and other tools handy. A little extra dirt may make the matrix more crumbly, but the whole thing duplicates sandstone.