Are there joints compensating for the deformation?
>>How do you rule out a slope failure which caused brecciation at the time of
>>the fall and then re-cementation.
>It is a very thin slab. To become recemented in place it would have had to
>slide as a unit with enough integrity to prevent fragmentation. It has
>come down several hundred feet of topographical relief, presumably over a
>ramp which no longer exists. If the slab was fully lithified and it became
>brecciated during movement, its present level of integrity could not have
>been maintained. I will try to get some photos up where you can see them.
I look forward to this. But I do have one possible explanation. If it moved
as a single unit, it would have had to have been lithified. If the slab is
thin enough, the deformation could be post-landslide. I would suggest an
alternative to this rock being soft when it slide. There is a grave in Rock
Creek Park which bears on this issue:
"There is a gravestone in Rock Creek Park in Washington, D. C>
which consists of a rectangular slab 70" long and 2" thick
supported by posts at each corner (it lies horizontally). It was
put in place in 1850. By 1903 the center had sagged 3" and by
1932 it had sagged by 4 1/2". Assuming a density of 2.7 for the
limestone of the slab, calculate the viscosity of the limestone
in poise."~Dave Wiltschko, Advanced Structural Geology Problem
Set, problem #3, University of Michigan.
This horizontal gravestone is real. You can find discussions of it in the
Rock Creek cemetery
"Figure 2: Marble slab in cemetery (north of Soldiers' Home,
Washington, D.C.), bent downward by its own weight. Caption and
photo by W. T. Lee (1925; photo number 3279, U.S. Geological
Survey Photographic Library." ~R. Dirk Titamgim, "Are there Rocks
that Bend?" Rocks and Minerals,67(May/June 1992), p. 195
The picture is fantastic get this article.
Rock Creek cemetery
"In any case, the resulting beding of a marble slab, such as
the one shown( figure2), is usually a fairly slow process: the
results become evident only after several months, or more
commonly after some years, of exposure. The term creep is
frequently used to describe such relatively slow plastic flow."
"Other examples include bending of some facing slabs of
Italian marble on the Lincoln First Tower in rochester, New York,
and on the Amoco skyscraper in Chicago---see figure 3. Those
slabs have been or are in the process of being removed as a
safety precaution. it was thought thaty they might bend,
separate fromt heir moorings and plummet to the street below."
~R. Dirk Titamgim, "Are there Rocks that Bend?" Rocks and
Minerals,67(May/June 1992), p. 195-196
He shows a picture of the Italian marble in his figure 3 It also is bent
Rock Creek cemetery
"Some of the more leisurely sightseers in the National
Capital make the pilgrimage to the Rock Creek Cemetery not alone
to see the Adams monument of Saint Gaudens but to examine the
marble tombstone which has become bent during the course of years
due to being supported on four posts under the ends but left
without support in the middle. The stone is 180 cm long, 90 cm
wide and 5 cm thick, and the sagging amounts to some 8 cm. The
amount of sag makes any effect due to solution or weathering
inadequate as an explanation. That the phenomenon cannot be due
to a simple elastic deformation seems equally beyond question,
for had the workmen who put the stone in place eighty years ago
noted a three inch sag they would undoubtedly have supported the
"This stone must ahve beend escribed by scientists in the
journals and it is altogether probable that elsewhere the
phenomenon is well known. Is the flow viscous or platic or a new
type altogether? The following has come to light.
"A note appeared in the Scientific American nearly a
generation ago on the 'spontaneous bending of marble' in which
this particular stone is referred to (Sci. Amer. 88, 134 (1903)).
it calls attention to a report by Dr. Alexis A. Julien in Volume
10 of the Tenth Census Reports where, in tablets...generally show
a slight curvature in the center... Dolomeiu first made the
observation on an Italian marble, called betullio, that it
possessed a degree of flexibility allied to that of the
itacolumite of Brazil.'"~Eugene C. Bingham, "An Ancient Problem
in Rheology," Journal of Rheology, 3:3(July 1932), pp 341-344.
He goes on to note many examples of rock on buildings which
flowed in response to gravity over a number of years.
I would suggest that this is the phenomenon which accounts for your rock
which conformed to the underlying Tonto surface.
>>I guess I need clarification on whether the deformation you speak of is
>>WITHIN the various blocks of Redwall or BETWEEN the fragments of the Redwall.
>The whole slab is deformed by the irregularities of the surface on which it
>>Concerning the slumps into the canyon: Slumps occur along any steep slope.
>>If an entire section of paleozoic rock slumped into the canyon, I wouldn't
>>find that surprising. What I would find surprising is internal deformation
>>of the block which slid--deformation not caused by fracturing but by soft
>>sediment flow. It is the internal morphology of the blocks which is
>>important and I can't get that info from what you wrote.
>What is *surprising* about the Surprise Valley slump is that it is huge and
>does not appear to be associated with any known faults (except it is of
>course itself fault bounded) and is a Toreva-type slump (base outward
>rotation). This type of slump occurs most readily in unconsolidated or
>partially consolidated materials, and the present condition of the canyon
>walls certainly does not encourage this kind of development.
This doesn't seem consistent. If the slump is fault bounded, then it IS
associated with known faults. What am I missing?
I am unfamiliar with a Toreva type slump. Is this the normal slump where
the whole pile rotates backward into the hill?
Adam, Apes, and Anthropology: Finding the Soul of Fossil Man
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