cave log
.......updated 2/10/03
In the summer of 1996 while involved in preliminary
hydrology studies in and around the Oregon Caves Monument, Steve Knutsen was
searching the area for any springs to sample for some proposed dye tracing. He
found a resurgence on the bank of a creek about the same elevation as the
Oregon Caves and some miles away. A few rocks were removed from the bank at
that time. Later, at Steve’s suggestion, a couple of guides, Brad and Josh,
who were working for the Cave’s Company did some more rock moving and started
a notch in the creek bank. Why look here for a cave? There was a seam of
marble exposed in the bedrock of the creek. The water flowing out of the creek
bank seemed to have very slight temperature variations, as cave water would
and not creek water just flowing through rock piles and log jams along the
creek. The water also seemed to have more even flow than the near by creek
had, being a major water contributor in late summer and fall but increasing
only a little from 1 cfs to maybe only 2cfs in the winter. All these factors
were positive for the existence of a cave, but how big? A 4" crack or
cavernous halls?
In the summer of 1998 work was resumed on the
resurgence. At this time a small notch had been cut in the talus slope of an
alluvial deposit (quaternary?) where the water exited the hillside. A brief
investigation showed that the resurgent stream was flowing out of the alluvium
over marble bedrock underlain by an argillite with a 7’ to 10’ drop to the
creek. We, David Hodges and Don Young, started following the water by the
simple procedure of removing any rocks or boulders that were loose where the
water was flowing. By this method a tunnel was soon created. The walls were
formed by stacking rocks along both sides of the water, until a ceiling of
suitable stable, clay layer was reached. Boulders and rock walls to a suitable
depth and height to stop erosion reinforced the sides. This hole was digging
itself. The rocks were generally loose with no or very little mud and gravel
around them. As we went into the mountain large rocks were used for walls and
small ones were carried out forming a tunnel with a natural clay roof.
It was observed that the water was flowing through
cracks between the boulders where sand and silt had been washed out by the
water action. It seemed that over the years the water had taken various
passages out of the alluvial boulders. The boulders were up to 3’ in diameter.
Bedrock was followed up from the creek, starting with argillite at creek level
changing to marble where the resurgence exited the hillside. Bedrock was not
seen again that summer. In the first year approximately 20’ of tunnel was
carved out from 5’ to 8’ high and wide. The walls, floor, and ceiling were the
creek alluvium and no more marble was seen since the entrance.
Digging resumed in the spring of 1999 and the first
marble appeared at 25’ in from the entrance. The marble soon formed a ceiling
about 5’ high with a marble wall on the east side and alluvium on the west
side. Three or four speleogenic boulders were found between 25’ and 35’ into
the tunnel. At this point the water was coming from the east side which
appeared to have a marble roof. More digging caused the water to move to the
west side of the tunnel where the water was flowing out of a 1 foot hole in
the marble at the top of what appeared to be a joint dissolution cave
passageway about 10’ farther back into the cave. The notch showed a marble
ceiling approximately 7’ back from this hole on the west side. Digging was
stopped until we could determine how safe it was. Stopping was wise. Within
one half hour of vacating the tunnel, a large (2’x3’x5’) speleogenic boulder
peeled off the east wall right where we had been sitting. Soon another
speleogen joined this one and now leans against the east wall near by. Any
boulder small enough to remove was taken out and the large ones, speleogens
and placer boulders, were stacked on the west side. It should be noted that
these speleogens seem to have been formed and loosened in situ by the
dissolving action of ground water and cave water flowing through a plugged up
cave. However, at this point, we couldn’t be sure that we weren’t moving along
a cliff face or amongst large marble boulders. We also considered it quite
possible that all the alluvium could have been washed in by the creek forming
the initial plug in a cave. At this time whether this is true had not been
ascertained, since not all the ceiling in this part of the cave was exposed.
The boulders were typical of the creek outside the cave. All the marble showed
dissolution characteristics with protruding chert lenses. The deeper we dug,
the smaller the alluvial boulders became.
We continued by following the water, stone by stone,
inch by inch. More marble started showing up to the east side and slowly
moving across the ceiling from the west. It was still not possible to say that
this was a cave, and not a heap of marble boulders. Any dangerous work was
done from a distance with long handled hoes and long pipes that would pick
away at the base of any dangerous rock. When severely undercut, the boulder
would fall out of the bank that held it. Then the long handled hoe would be
used to hook the rock and drag it back to where it could be safely handled.
Small rocks were thrown out of the tunnel. Moveable boulders were used to
support walls in the alluvial entrance and immovable boulders were left in
place. A large rock, 3’x3’x2’, was found in the middle of this area. The upper
half of it showed no water action. It was undercut by the water, and fell and
broke into manageable pieces. It appeared to be a fractured chunk of the
intrusive dike noted in the bedrock of creek outside the cave.
Soon after this rock was removed, natural water action
undercut and collapsed a large section of the east wall. As the rubble was
cleared away and more marble was exposed, it became apparent we were indeed in
a cave. On August 16, 1999, I the author, David Hodges, recognized this
resurgence to be a cave. This was witnessed by assistant, John Dodge. At this
point in the digging we were almost through the first room in the cave we
called the Boulder Patch.
