Fossilized Muck (Chert)

When the debris of life fall into water or plants and animals die in the ocean, sometimes they sink to the bottom and decompose form an organic muck. Think of leaves and dead stuff rotting on the bottom of a pond. When the muck is covered up, such as by soil washing into the pond during flooding or limestone ooze settling over ocean-bottom muck, the muck can become fossilized. Around Las Vegas, fossilized muck is most often recognized as layers of unrecognizable "fossiliferous material" that punctuate layers of gray limestone. Occasionally, shells or other fossils can be seen in the muck, but usually it is simply reddish-brown, unrecognizable, dark-colored stuff mixed into the gray limestone rock.