Steve LeMaster wrote:

"Geologist have calculated that the Grand Canyon is 6
million years old. Due to the fact that it is 6,000
feet deep from its deepest point, this indicates for
every one million years the rock erodes 1,000 feet.
So, for every year over the past 6 million years,
the Colorado River has eroded the bedrock .001 feet,
or .12 inches per year.

Using the Grand Canyon as a model, it would take 3,000
years to erode three feet and 6,000 years to erode
six feet in the Sphinx enclosure."

This is a completely meaningless comparison as types
of erosional processes acting in the Grand Canyon are
quite different and more varied from those those
occurring in the Giza Plateau and they are acting
on a variety of different types that are also quite
different from those found in the Giza Plateau and
being controled by varying climatic conditions. This
comparison is also scientifically invalid as the rate
of erosion in the Grand Canyon has varied so much
over the last six million years, as the various
environmental factors, i.e. stream flow, climate,
and others have changed, to the point of rendering
the average value of erosion a rather meaningless
number. It is impossible to use the Grand Canyon as
a model for Sphinx erosion because the overall lack
of any similarity in climate, rock types, and
erosional processes involved.

Unless the rock type, climate, and environmental
setting, for which the weathering data is collected,
is very similar or identical to that of the Sphinx,
it is quite nonsensical to use it in a scientific
discussion of the age of the Sphinx. Also, in order
to use weathering rates to date something, a person
must demonstrate that the rates of weathering have
remained constant over the period of time in question.
This is a problem as small variations in environmental
conditions can cause large changes in weathering rates
to the point of truning any such calculations into
exercises in boring fiction.

Yours,

Paul
Baton Rouge, LA