This formation is approximately 250 feet thick and is composed of layers of metamorphosed shale called phyllitic shale, and the lower portion is composed of greenish brown quartzite. This formation was deposited in a slightly deeper, lower energy marine environment. C ontinue up the trail for approximately 600 feet until you have reached the last prominent quartzite outcrop on the south side of the trail. Trace Fossils C losely examine the outcrop on the south side of the trail for small linear rust stains, as well as small circular stains. These tiny rust stains are actually trace fossils.
Trace fossils are indications of organic activity such as tracks, trails and burrows.
The fossils you are looking at are burrows. These were left by tiny animals which moved, and burrowed, in the sandy ocean bottom. This is further evidence of the nature of the depositional environment. The ocean that deposited the Tintic Quartzite was gradually increasing in depth. At this location, sand and mud were now being deposited.