Download Types of stratigraphic discontinuities

UNIT
12
The history of the Earth
TYPES OF STRATIGRAPHIC
DISCONTINUITIES
Biology and Geology 4. Secondary Education
UNIT
UNIT
12
3
Types of stratigraphic discontinuities
Stratigraphic discontinuity is the absence of the
stratigraphic record for a specific period.
There is a geologic time interval in the Earth's history,
between two sequences separated by a discontinuity, that
is not represented by sediments.
There are many types of discontinuities:
Biology and Geology 4. Secondary Education
UNIT
UNIT
12
3
Types of stratigraphic discontinuities
ANGULAR UNCONFORMITY
Young horizontal
series
Old folded series
Discontinuity between an older stratigraphic series which
folded and eroded when the strata were exposed to the
weather and a more recent stratigraphic series.
Biology and Geology 4. Secondary Education
UNIT
UNIT
12
3
Types of stratigraphic discontinuities
DISCONFORMITY
Series deposited after the erosion of the previous series
Discontinuity between an old stratigraphic series which
underwent a period of erosion and the more recent
stratigraphic series which was deposited after that process.
Biology and Geology 4. Secondary Education
UNIT
UNIT
12
3
Types of stratigraphic discontinuities
NONCONFORMITY
Young sedimented series
Old eroded granite
Discontinuity between an old series consisting of eroded
rocks (e.g., granite) and the more recent sedimentary
strata.
Biology and Geology 4. Secondary Education
UNIT
UNIT
12
3
Types of stratigraphic discontinuities
PARACONFORMITY
Recently
deposited
young series
Interruption in
sedimentation
over several
million years
Old series deposited
millions of years ago.
Discontinuity between an old series deposited many
millions of years ago, after which there was an interruption
in sedimentation over millions of years, and the more
recent stratigraphic series.
Biology and Geology 4. Secondary Education