Dinosaur footprints

About 150 million years ago dinosaurs roamed over this plateau.  I'm not paleotologist but I gather that when these particular dinosaurs were here it was muddy and, not long after their footprints had dried out, a volcano erupted setting them in stone.  A while later (no idea how long) they were covered by another layer of stone, probably from another volcano, which preserved them.  Another while later (much more in our era) a land slide, or something similar, caused the second layer of stone to crack revealing the footprints. Some of the footprints were quite big - three of us sat in one, one in each toe - and to be honest it was quite awe inspiring and well worth the slog up to the plateau.