Re: [pct-l] Hey, easy on the "easy-PCT"

[Greg Hummel <ghummel@hydrogenburner.com>]

Former Attorney General Edwin Meese wrote:

>In terms of rocks AT is granite pretty much the entire way, PCT
>gradually changes from granite to volcanic midway through. 

Actually the PCT starts out in sedimentary rock throughout most of southern
Calif. with granite exceptions of San Jacinto, San Bernardino and San
Gabriel Mtns. then goes back to sedimentary between the San Gabriels and
the Tehachapi's.  The Sierra's are mostly granite but the PCT actually
crosses classic example of what geologists call "roof pendants", former
sedimentary rocks that existed prior to the emplacement of the Sierra
granite plutons.  These cooked, squeezed, intruded, pressurized and mostly
beat the hell out of the sedimentary rocks until they are now considered
metamorphic rocks.  A look at the Ansel Adams Wilderness area from the air
(or the top of Banner or Ritter Peaks) shows that all of the ridges and
valleys there follow massive stratified layers of metamorphic rocks laid on
edge.  The most of northern California crosses sedimentary rocks again
until you hit Lassen.  The volcanic rocks start in earnest there and
continue thru Oregon until you hit the granitics of the north Cascades in
Washington.  

The great contrast in the geology between the PCT and the AT is that the
west coast geology is all still active!  That is the plates are moving (the
San Andreas fault, San Jacinto fault, the Garlock fault, just to name a
few), the volcanoes are erupting (Mt. St. Helens and many other active
volcanoes), the granite is still intruding (a rising granitic pluton is
thought to be causing the multitude of ever shallowing earthquakes in the
Mammoth Lakes area) and the mountains are still rising (the Northridge
earthquake caused the mountains to the north, near Aqua Dulce, to rise
about four inches).  If you are just lucky enough, during the five or six
months it takes to hike the PCT you might just have your life time line
cross the geologic time line (a truly rare and magical occurence) and
witness first hand one of these active processes. 

On the AT nothing much has moved much other than an occassional small
earthquake or two for, oh, twenty million years or so, and isn't likely to
for another twenty million years.  Is there even a volcano any where on the
AT? 

IMHO.

Take great strides .  .   .

Greg "Strider" Hummel
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