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Stop # 6 Boulders
These two large
boulders look nothing like the surrounding rock. However,
they look very similar to the rock type located well up
the mountain. In fact,
they are identical to the grey rock which can
be seen above. The dark gray boulder (on the bottom) is
limestone, most likely from the lower portion of the
Maxfield Limestone (see geologic map). The light gray
boulder (on top) is dolomite, most likely from the upper
portion of the Maxfield Limestone (see geologic map
description).
Ophir Formation
(elevation 5,500 feet)
The surrounding rock on the canyon walls looks nothing like the steep faced walls indicative of the Tintic Quartzite. In fact, the slope is reduced and the rock is very broken and eroded. In addition, there is a significant increase in the amount of vegetation. This point marks the change from the Tintic Quartzite to the metamorphosed shale of the Ophir Formation. 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.
Continue up the trail for approximately 600 feet until you have reached the last prominent quartzite outcrop on the south side of the trail.
Closely 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. The mud was turned to shale and the sand to sandstone after they were deeply buried and many millions of years had passed. Even later, after being buried more deeply, the sandstone turned to quartzite and the shale into phyllite.