Looking for San Andreas fault from highways 41/46
Kathy Rages
where do you cross the San Andreas fault and how visible is it? (I have
relatives coming from Missouri.)
Kathy Rages
Chuck Fry
If memory serves (and it's been a year since I drove through the area),
the fault is on the common stretch of 41/46 between the junctions of the
two highways, near the "town" of Cholame (and the James Dean memorial).
I seem to remember that the fault trace is readily visible.
There is a back road you can take south from there to CA 58 through the
Carrizo Plain, whose name escapes me, but it basically follows the fault
trace the whole way. Again, my memory is hazy, but I remember it is
either a good gravel road or a bad paved road. In either case most cars
should be able to handle it without difficulty.
-- Chuck, needs a road trip soon
--
Chuck Fry chu...@rahul.net
1791: US Constitution adopted, giving sweeping new powers to the people.
1993: Clipper chip proposed, giving sweeping new powers to the police.
What has happened to the US Government in the intervening 202 years?
Andy Michael USGS Guest
>In article <2u9uro$g...@news.arc.nasa.gov>,
>Kathy Rages <ra...@anarchy.arc.nasa.gov> wrote:
>>When driving from Visalia to the coast (Morro Bay/Cambria) on CA 41 and/or 46,
>>where do you cross the San Andreas fault and how visible is it? (I have
>>relatives coming from Missouri.)
>
>If memory serves (and it's been a year since I drove through the area),
>the fault is on the common stretch of 41/46 between the junctions of the
>two highways, near the "town" of Cholame (and the James Dean memorial).
>I seem to remember that the fault trace is readily visible.
On 46 just east the Dean Memorial (worth a stop, BTW) you can either
turn north and go to Parkfield (like the driver that collided with Dean
so watch out for fast moving traffic) or there is another small road that
follows the west wall of the valley to the south. If you drive along this
road and find a place to park you can find a few streams that take
right lateral bends because of fault movement. The bend shows you where
the fault is:
|
| Map of Stream
|
/
-- fault is along here
/
|
|
|
Side Road
Cholame Valley
A few of these are so obvious that I was able to find them. I know you
are thinking, but he's a seismologist. But I'm also a pathetic field
geologist and geomorphologist. One even has a little dirt jeep trail
along it that follows the stream.
Cholame Valley is there because the fault, at least at the surface, has
a step in it, to the north the fault is on the east side of the valley
and is not as well expressed.
If you drive into Parkfield you will eventually find the Parkfield Bridge
(it's just a low bridge with white guardrails, there is a larger green
truss bridge around but just ignore it). The Parkfield Bridge goes over
the fault and you can see that it is being bent by looking down the
guardrails (one is better than the other). If you go underneath (depends
on the water, but should be dry now) the supports are twisted too.
Have fun,
Andy
Glen Blankenship
The San Andreas fault crosses Highway 41 just after it joins Highway
46, about a mile east of the town of Cholame. The fault runs parallel
to Cholame Valley Road to the north, and Davis Road [also shown as
the southern half of Cholame Valley Road on some maps] to the south.
Sunset's EARTHQUAKE COUNTRY describes the area south of Highway 41/46
(beginning at Still Lake just north of the Palo Prieto Pass and
heading north) as follows:
"Still Lake and a steep scarp mark the fault line just north of
Carter Grade. Though it is far from the road, the fault zone north
of Still Lake can be clearly traced from the air or on maps by the
straight line of lakes - Twisselman, O'Brien, Long - that mark its
route.
"A row of impressive scarps and offset drainage lines is visible west
of Davis Road [which my map shows as Cholame Valley Road] just before
it meets State Highway 46 [which is also Hwy 41 at that point] (the
best example of offset drainage is 1.1 miles south of the highway).
On the flat plain east of Davis Road an oil company pipeline has
been mounted on skids to provide some "give" in case a major
movement takes place along the fault."
North of Highway 41/46, the fault continues up the Cholame Valley:
"Cholame Valley is a sunken block between two active brances of the
fault zone. The eastern branch is difficult to trace in the valley,
but the western branch is visible as a low, discontinuous scarp
at the base of the ridge bordering the valley. Where the main road
to Parkfield follows this ridge, the scarp and sag areas show up at
the edge of the roadway."
=-=-=-=-=-=-=
Hope that helps!
+---------------------------------------------------------------------+
| Glen Blankenship | obo...@netcom.com | g.blan...@genie.geis.com |
| Church of the Holy Toy - "We are seriously silly." |
| Remember: He who dies with the most toys, dies. |
+---------------------------------------------------------------------+
George L. Westlund
I believe it crosses both highways a short distance east of where they
come together just east of Cholame. Usually, I've only seen evidense
within a time period after a surface movement that damages the pavement.
Other than that, you do see several shacks around with antennas on them
(right when you cross the creek after 41 & 46 come together).
--
George L. Westlund || Internet: gwe...@calpoly.edu
Academic Computing Services || BITNET: DI...@CALPOLY.BITNET
Cal Poly || NoiseNET: (805)756-6543
San Luis Obispo, CA 93407 || FAX: (805)756-1536
Glenn Mandelkern
>In article <2u9uro$g...@news.arc.nasa.gov>,
>Kathy Rages <ra...@anarchy.arc.nasa.gov> wrote:
>>When driving from Visalia to the coast (Morro Bay/Cambria) on CA 41 and/or 46,
>>where do you cross the San Andreas fault and how visible is it? (I have
>>relatives coming from Missouri.)
>
>If memory serves (and it's been a year since I drove through the area),
>the fault is on the common stretch of 41/46 between the junctions of the
>two highways, near the "town" of Cholame (and the James Dean memorial).
>I seem to remember that the fault trace is readily visible.
This also appeared on local news on Channel 7 (KGO) when Good Morning America
did their Pacific Coast Highway tour over a week's time. Look eastward
from the intersection of Cholame Valley Road and 41/46. This road is found
where you'll see a sign that reads "Parkfield 15" with an arrow pointing
to the left.
If you're on 46 going west, you'll be in the fault's territory about 5 miles
after you pass a sign stating "Polonio Pass" along with its elevation.
>
>There is a back road you can take south from there to CA 58 through the
>Carrizo Plain, whose name escapes me, but it basically follows the fault
>trace the whole way. Again, my memory is hazy, but I remember it is
>either a good gravel road or a bad paved road. In either case most cars
>should be able to handle it without difficulty.
This is Soda Lake Road.
Most of Soda Lake Road has been repaved from 58 to about 3 miles south of
Soda Lake. Afterwards, it is a good gravel road for about 5 miles and then
it is paved again, until it finally ends at 166.
If you are a member of CSAA or AAA, ask for the Sequoia map. It covers
the area between Visalia and Morro Bay along with these roads. If you get
one of the San Luis Obispo County maps from Compass or Rand McNally,
please be aware that some of the roads drawn in the areas between 58 and 166
are private--I found this out the hard way when I tried taking Branch
Mountain Road and found a closed fence, armed with 11 combination locks!
Lastly, the California maps from Gousha show the layout of the Carrizo
Plain and the Temblor Range (temblor is Spanish noun meaning "shaking")
in relation to Soda Lake Road, 33, 41, 46, 58, and 166.
For sure, Soda Lake Road is public, I have taken it many times between
in both directions. As Chuck said, any car should be able to handle it.
Lastly, a really good book which covers this area is entitled
"Making the Most of San Luis Obispo County". There is a chapter which
covers the eastern section of this county, including Cholame and Soda Lake.
It costs $9.95.
Also, Soda Lake is covered in one of the books by Ron Stob, either
"Back Roads of the Central Coast" or "More Back Roads of the Central Coast".
--
_______________________________________________________________________________
Glenn Mandelkern Hee, hee, hee, hee!
gma...@megatest.com Questor the Elf lives!
(408) 451-3270
Steve Allen
Glenn Mandelkern <gma...@megatest.com> wrote:
>If you are a member of CSAA or AAA, ask for the Sequoia map. It covers
>the area between Visalia and Morro Bay along with these roads. If you get
>one of the San Luis Obispo County maps from Compass or Rand McNally,
>please be aware that some of the roads drawn in the areas between 58 and 166
>are private--I found this out the hard way when I tried taking Branch
>Mountain Road and found a closed fence, armed with 11 combination locks!
Also, AAA members may want to obtain the ACSC map of San Luis Obispo
County. This is probably the next best thing to exploring for all
the locked gates yourself.
This map covers the San Andreas from north of Parkfield down to Hwy 166,
and the cartography is the usual exquisite work done by ACSC showing
most of the topography without actually using contours.
If you walk along the fault just east of Soda Lake where it nestles
against the foothills you can see many offset streambeds of various
sizes and actually jump down into some of them and see the 1857
crack still visible in the soil.
There is also a sag pond along there. I've been there when it was dry
and at either end there were depressions in the mud where the water
had drained. Kerry Sieh said that he had been there when it was wet
and he could hear the water gurgling way, way down. It felt kindof funny
to be standing on that depressed mud after he said that, so I moved.
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064
s...@lick.ucsc.edu Voice: +1 408 459 3046 FAX: +1 408 454 9863
<a href=ftp://lick.ucsc.edu/pub/www/sla/sms.html>Seabright Morris & Sword</a>
Richard Stead
>ra...@anarchy.arc.nasa.gov (Kathy Rages) said...
>>When driving from Visalia to the coast (Morro Bay/Cambria) on CA 41 and/or 46,
>>where do you cross the San Andreas fault and how visible is it? (I have
>>relatives coming from Missouri.)
>
>come together just east of Cholame. Usually, I've only seen evidense
>within a time period after a surface movement that damages the pavement.
>Other than that, you do see several shacks around with antennas on them
>(right when you cross the creek after 41 & 46 come together).
It's been several years since I was there, but I think I remember where
the fault is. As you are going toward Cholame, you go around a broad
curve in the road in a valley and head toward a slope on the side of the
valley. The slope looks something like:
------
\
\
--
* \
* \
The stars mark the location of the fault (imagine you are looking at a
slice into the side of the hill). The fault is parallel to the face
of the hill. If you follow the hill, you can see where the fault
has offset small drainage channels. If you want to follow it up close,
be sure to ask permission from the property owners first, and don't
disturb any equipment.
--
Richard Stead
Arlington, VA
st...@seismo.css.gov