San Andreas Fault

A drive along the fault.

Background Information

The San Andreas is a Slip Fault…

What does that mean?

It is two pieces of earth slipping past each other.

There areThree types Of faults:

1.Normal2.Reverse3.Slip

Why does the earth move?

The earth is dynamic!

That means it is in motion!

The earth is in layers…

The crust, the layer we live on floats on the thick mantle, which is fluid.

The Earth’s Crust

The earth’s crust is not one whole piece…it is in pieces that move around…

Scientists call these pieces “plates” and the study of the movement of these plates is called Plate Tectonics.

The San Andreas Fault

The San Andreas Fault is a boundary between the North America Plate and the Pacific Plate.

These two plates are both sliding past each other and in some places the Pacific Plate is sinking beneath the other.

How do earthquakes happen on the fault?

As the plates move past each other, the rocks get stuck and build up energy.

Eventually, the rocks can no longer withstand the build up and they break!!

Result:

How often does the San Andreas fault produce large earthquakes?

• Pallett Creek: – every 130 years on average

• But varies from 45 to 300 years

• Wrightwood: – every 100 years on average

• But varies from 62 to 192 years

Devore: – Every 150 years on average

• So when should we expect the next earthquake?• It’s been 193 years since the last one in San

Bernardino (in 1812).

How strong would the shaking be?

Factors that affect how strong the shaking in an earthquake will be

1) Earthquake magnitude

2) How far away the earthquake is

3) Soil conditions

Earthquake Waves

Earthquakes create several different types of waves.

p waves are compression waves

(like sound).

s waves are transverse waves that move side to side or up and down.

The Beginning

At the start of the trip we must all first pick up a forest pass from the Chevron station at the bottom of the pass.

We will meet up at the McDonald’s adjacent to the Chevron station.

You must pick up your $5 pass first!

Mormon Rocks

Our first stop is the Mormon Rocks.

Mormon Rocks

The Mormon Rocks were created

thru uplift of the fault.

They are sandstone,

but are fairly resistant

to weathering.

Mormon Rocks

Mormon Rocks

Lone Pine Canyon

The next part of the trip is along Lone Pine Canyon Road. This road and canyon directly follow the fault…In fact, this canyon is a direct result of the fault.

Marble Quarry

Traveling up Lone Pine Canyon Road towards Wrightwood, we stop at an old Marble quarry.

We stop here to collect marble samples before moving into Wrightwood.

Look for other rocks like actinalyte as well!

Marble Quarry

Marble Quarry

Plants at the Marble Quarry

At the quarry you will see various plant life representative of the lower valley.

Plants at the Quarry

Plants at the Quarry

Plants at the Quarry

Lone Pine Canyon Road through Wrightwood

We follow Lone Pine Canyon Road to Highway 2 and head west on Hwy. 2.

The fault runs through Wrightwood and here in Wrightwood is the sight of one of the largest earthquakes in the history of the fault, the 1857 quake.

Big Pine Information Center

The Big Pine Information Center is the next stop.

Here we will look in the small store and walk along a nature trail.

Big Pine Information Center

This tower sits on the fault. It is the highest point on the San Andreas Fault.

Big Pines Highway

We travel along Big Pines Highway now on the edge of the fault!

Appletree Campground

We will stop on the side of the road (Completely off the road!) and walk across the road to the Appletree Campground where we will then walk up a short forestry road to look down at the fault and collect some “fault flower”.

Lunch!!!

Lunch will be taken at a little off the road picnic area called Mescal Picnic Area.

Yummm…

Jackson Lake

Last stop…

Jackson Lake

Jackson Lake is a creation of the fault.

It is a sag pond…an

area which sank

as a result

of the fault.

Jackson Lake

Go Home!!!

Head back through Wrightwood on

Highway 2 and to

Highway 138…

Have a Safe Trip!

God Bless!