Still digging, after all these years.

but until then, we wanted to bring a word about:

SEDIMENTARYAND VOLCANIC BEDROCK UNITS
La Habra Formation, undivided (late Pleistocene)Siltstone, thick-bedded friable sandstone, pebbly sandstone, and pebble-cobble conglomerate; locally abundant clasts of platy white siltstone.

This stuff is really hard to dig.  Also, it wasn't created 6000 years ago, but you can believe that if you want to.