Folding--
Anticlines & Synclines
Law of Horizontality....
When rock layers are
deposited, they are
deposited horizontally.
Look at the sand on the
beach, it’s a horizontal
surface!
Folds....From Compression!
During mountain building,
flat-lying & volcanic rocks
are often bent into
wavelike undulations--
called folds!!
Most folds are the result of
compressional stresses!
Think about the bend along
San Andreas Fault & our
local mountains!
Parts of a Fold...
Limbs: The two sides of a
fold
Axis: A line drawn along the
points of maximum
curvature of each layer.
**The oil derricks off of
Santa Barbara are located
along the axis of an
anticline!
Anticlines:
- • Anticline:Astructurein which the oldest strata (rock beds) are found in the center
- • Anticlinesare commonly formed by the upfolding or arching of rock layers.
Synclines....
Syncline: A structure in
which the youngest strata
(rock beds) are found in
the center
Synclines are
commonly formed by
the downfolds or
troughs of rock layers.
Oil Traps
Oil/petroleum is collected
between interconnected
rock particles of
sedimentary rocks
(permeable rocks).
Liquids can flow through
these spaces!!
Cap Rocks....
- • 3) Hydrocarbons & water move upward until they meet a layer of impermeable rock--a rock through which liquids cannot flow
- • The impermeable layer is usually a shale & is called a cap rock
1) As sedimentary rock becomes deeply buried under overlying sediments, pressure increases.
2) This forces water &
hydrocarbons out of pores
& up through layers of
permeable rock--to cap
rock
Oil Traps....
4) Hydrocarbons that accumulate beneath the cap rock forms an oil reservoir by saturating all the spaces between the rock particles.
Oil Traps....
5) Petroleum is less dense than water. Therefore it will float on top
of any trapped water.
Natural gas is less dense than petroleum. Therefore, if present, it
will float on top of petroleum.
Question:
What will happen if the cap rock is fractured?