Conglomerate is sedimentary - I think I might go for one of those fridge cake mixtures.

The problem is that it should be formed in the same way as the original, with carbon based chemistry replacing the silica.

The BBC web site on geology suggested marzipan layers all scrunched up for metamorphic rocks, and I'm all set for that.

What's Christmas candy? Is it like rock candy crystals?

Penny