'Uplift' baffles scientists, transforms area beach

[Cricket]

'Uplift' baffles scientists, transforms area beach



BY MICHAEL ARMSTRONG
STAFF WRITER
Like a giant fist punching through the earth, a 1,000-foot long
section of the
beach below Bluff Point rose up 20 feet from the tidelands sometime
last Friday
or late Thursday, pushing boulders up from the ocean bottom, cracking
sandstone
slabs and toppling rocks upside down.

Below Bluff Point, a new fissure opened up at the base of the 800-foot
high
cliff. The uplift could be a re-activation of a landslide that
happened perhaps
12,000 years ago.



Photo by Michael Armstrong

Two men climb an uplift on the beach below Bluff Point on Sunday.

"There was just beach before," said Ron Hess, who lives on Bluff Road
above the
new uplift. "Now there are tidal pools."

"You can see a rock circle," said Marilyn Hess. "All you used to see
was one big
rock, and now you can see this uplift of rock."

Scientists don't know exactly what caused the uplift. It would take an
earthquake over magnitude 7 to cause an uplift that high, said Peter
Haeussler,
a geologist with the U.S. Geological Survey in Anchorage.

"I have no idea," he said when he first learned of the uplift. "This
sounds
really, really bizarre."

The uplift runs in an arc around a small cove about 1.3 miles east of
Diamond
Creek Beach, a pleasant day hike accessible from a trailhead near
Diamond Ridge
Road and the Sterling Highway (see Outdoors, page 16). Where tide-
covered
boulders had once been, the ground now rises up in a long ridge of
gray clay,
sandstone, coal and barnacle-covered boulders. In last weekend's heat,
rockweed
had dried up and mussels rotted. The cobble beach itself seemed
higher. Small
rockfalls trickled down to the beach.

Visitors to the beach on Friday morning after low tide reported the
rockweed
remained wet and fresh, suggesting the uplift happened sometime early
July 3 or
late July 2.

The Hesses said they didn't feel any major earthquakes, and none were
measured
by USGS. They said they felt some small earthquakes last week.

"They felt like three-pointers to us," Marilyn Hess said. "We thought
'It's
probably Redoubt.' They didn't feel like hook-and-shake. They felt
like little
bumps."

Haeussler ruled out an earthquake causing the uplift.

"You would have felt a huge earthquake if it was earthquake related,"
he said.

Ed Berg, a naturalist with the U.S. Fish and Wildlife Service, Kenai,
visited
the site Sunday. He said at first he thought the uplift could have
been
earthquake related. The west-northwest to east-southeast orientation
of the
uplift cuts across known earthquake faults that run southwest-
northeast.

Bretwood Higman, a Seldovia geologist with a Ph.D. from the University
of
Washington, Seattle, speculated that the uplift could have been caused
by
reactivation of a 9,000 to 12,000-year-old landslide of Bluff Point.
The ancient
landslide would have eroded into the current bench below the Bluff
Point cliffs.

"It must have been a long time ago. It all had been beveled off into a
nicely
sloping beach," Berg said.

According to "Bluff Point Landslide: A Massive Rock Failure near
Homer, Alaska,"
a 1979 paper by Dick Reger, a geologist with the Alaska Division of
Geological
and Geophysical Surveys, a 1.5-mile long landslide below the cliffs
running
below Baycrest Hill happened sometime after the last glaciation,
perhaps 9,000
to 12,000 years ago. Wood found in the landslide has been carbon dated
at about
1,500 years old, Reger wrote.

Higman said that below the bluff and bench might be a curving zone of
weakness,
with the curve sloping up toward the beach. A huge land mass above the
zone
might have slipped, with the underground or beach end rotating up,
thrusting the
clay and rocks above it and causing the new uplift. The test of his
theory would
be to look for inland fissures, or scarps, at the base of the bluff.
The Hesses
said that's what they have seen.

"You can look down and see those crevices," Ron Hess said. "There's no
doubt.
It's quite noticeable."

"It's a big sand scoop," Marilyn Hess added. "The cracks are big and
black."

Why the uplift happened now -- and didn't happen in the 1964 Great
Alaska
Earthquake -- is unknown.

"That's what's really mysterious here is 'Why now?'" Higman said.
"There weren't
any substantial earthquakes. The ground wasn't really wet."

The area below Bluff Point is undeveloped, with only a few beach
cabins and
Overlook Park, part of Kachemak Bay State Park. Closer to Homer,
though, are a
few subdivisions on the bay side of Baycrest Hill.

"It has implications for that big slide block in general," Higman
said. "It says
things are still loose there. It must have been a substantial movement
to push
up that big a beach surface. That's relevant to people who live in the
area.
It's an important thing to investigate."

No field work by state or federal geologists has yet to be done,
although
Haeussler said he would be interested in examining the site. Berg
thought the
uplift could begin to erode with the next cycle of high tides and fall
storms.
The uplift is accessible on low tides and visible on high tides.
Unstable ground
and deep cracks make walking on the uplift treacherous. There also is
a deep
hole about 10-feet wide and 7-feet deep on the beach side of the
uplift -- wide
enough to swallow a four-wheeler.

"It's very intriguing," Higman said. "It certainly threw me for a
loop," he
added.