Mount Rushmore

Deborah Confer <deborah.confer [at] colorado__edu> writes

>The comments of a friend who works for the National Park Service are
>below.  The comments are her opinion and do not necessarily
>represent the position of the NPS.
>
>Simon Barcham Green <simongreen [at] aol__com> writes
>
>>...
>>I don't know the answer to Bud Goldstone but I wondered why lichen
>>and mold are considered a problem on a mountain sized sculpture.
>>...
>
>I would guess that the plant life is a problem for 2 reasons:
>
>    1.  The mold and lichens discolor the stone.
>
>    2.  Other plant roots penetrate the stone, they open up little
>        cracks for water to get in. The freeze thaw cycle would,
>        over time, make the cracks bigger and ultimately lead to
>        more problems, greater cracks, etc.
>
>The idea of a "mountain size" sculpture not being susceptible to
>these things is funny. After all, plant roots and the freeze thaw
>cycle have helped to break rocks down into smaller rocks for time
>immemorial. It would seem that "small loss" of rock on this scale
>would ultimately lead to larger loss of rock.

Deborah Confer is amused because she interprets my email as implying
that mountain sized sculptures would not be susceptible to lichen,
roots, cracking etc. If she re-reads what I wrote she will see that
I did not suggest that these things don't happen but did question
whether they were a problem in this context. Mt. Rushmore and the
parts of it that are sculpted will eventually crumble and erode to
nothing. We all know that and that the lichens, roots, mountain
goats, frost etc all contribute to the process. No doubt the artist
knew that too and maybe expressed a view on how to respond to
natural processes. The proportionate impact on a mountain sized
sculpture may well be greater than on a stone carving a few feet
high.

Detritus and roots will damage a rock face but I suggested they
could have some protective effects too--compare erosion on forested
and deforested slopes.  Suitable earth scientists could comment on
this better than me or possibly Deborah and her friend.

If the real reason Mt. Rushmore is being cleaned is because it's
free, this raises a whole range of issues. I am sure there are large
number of people out there who would gladly clean famous paintings,
polish bronze sculptures etc for free--and sometimes get good
publicity for their services. Should curators and conservators let
them?

PS: Do we know whether any small pieces of rock were dislodged by
the high pressure water?

Simon


                                  ***
                  Conservation DistList Instance 19:9
                  Distributed: Friday, August 12, 2005
                        Message Id: cdl-19-9-006
                                  ***