GEOLOGY OF OLYMPIC NATIONAL PARK:
PART Il NOTES ON THE GEOLOGY
Hurricane
Ridge Road
STOP 10:
Hurricane Hill Trail The old
roadcut along the Hurricane Hill Nature Trail reveals alternating layers
of gray sandstone and shale. These rocks have been strongly folded,
and in the outcrop along the trail, the careful observer can trace sandstone
beds around the bend of the fold (fig. FT 21).

Fig. FT 21.
Folded thin-bedded sandstone and shale.
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At the
last climb of the Hurricane Hill Nature Trail, where the trail begins
to zigzag, the mountain stroller reaches the first thin beds of volcanic
rock (of the Crescent Formation)
that spilled out across the ocean floor about 55 million years ago.
To the left, these lavas make small, rugged cliffs. Rubble weathered
from alternating layers of dark volcanic and sedimentary rocks is found
all the way up to the gentle meadow on top of Hurricane Hill. Much of
the volcanic rock here is sprinkled with white dots which are small
cavities filled with white minerals, mostly calcite and zeolites. The
cavities were formed by gas bubbles escaping from the once-molten rock.
Later the zeolite and calcite precipitated from mineral solutions in
the rock and filled these fossil bubbles At the very summit, where the
old fire lookout used to be, is a ledge of pillow basalt, much like
that described along the Dungeness River (Field
trip stop 1).
The main
mass of the submarine volcanic field, now tilted on end, can be seen
on Mount Angeles across the valley to the east.

Fig. FT 22. Cross Section of Klahhane Rige area showing tipped
up volcanic field (the Crescent Formation) and other rock units.
For a key to the colors see the
geologic map. |
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