Wednesday, September 1, 2010

Dinosaur Fossils Impression Activity

At the beginning of our activity we looked at this real fern fossil (from Pennsylvania). We talked about how ferns have been around for millions of years and fossil records indicate they were around well before dinosaurs (we referred back to the chart we have on "what came first" from a previous day.)  Then we went into our woods and looked for different kinds of ferns for making our own fossil imprints.

We gathered our ferns and looked closely to see which one looked most like the shale fossil we had.
Using this cute coffee-clay recipe (below), we made impressions.  After a lot of tries, the kids decided ferns just didn't make a very good impression.  We talked about how conditions really had to be right for a fossil to be made.

Then we went on to make dinosaur tracks and trilobite impressions (I bought a plastic trilobite at the LaBrea Tar Pits in Los Angeles earlier this summer.)  Of course I pointed out to the kids that trilobites and dinosaurs were not around at the same time (and once again we looked at the chart of "what came first.") ED especially enjoyed this activity and spent well over an hour making dinosaur tracks again and again!
Lots of people probably know about this "rock" clay recipe which is great for making fossils, but it's worth sharing again here:
1/2 cup salt
1 cup flour
1/2 cup coffee
1 cup used coffee grounds
(I drank all my coffee that morning, so instead I put some coffee into a pot on the stove, brought it to a boil, let it cool a bit then added salt and flour.  I didn't follow the recipe exactly as written.)

Since we now live in a more humid area, I opted to bake our fossils slowly at 325 for 45-60 mins since we have it hanging around while we do our dinosaur unit. (But warning--it's smelly!!)


  1. Wow! You're dinosaur theme is GREAT! And thanks for the recipe, I didn't know that one.

  2. Thanks for the recipe. I'll be using it tomorrow with my dinsosaur unit!