Ayup & thanks!
It's a cool site!
"What's going on there then" - do you mean just the tinyness of the chamber, or the little 'model' dolmen inside?
The 'Grand' one - the double-deckery-typethang, is the one that freaked us a bit! http://www.themodernantiquarian.com/site/10499/grand_dolmen_de_ferrussac.html
But actually, once you can see it 3-D it makes more sense as a low passage leading into a tall chamber. Dolmen 1 de Coste-Claude is a prettier version http://www.themodernantiquarian.com/site/10498/dolmen_1_de_costeclaude.html (tho no less freaky!)
love
Moth