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Geologic History
F SSILS
WHAT ARE FOSSILS?
the remains or trace of a oncethe remains or trace of a once
living thing, usually preserved inl...
F SSILS- How are they
formed?
ALIVE
F SSILS
DEAD AND
DECAYING
F SSILS
HARD PARTS
LEFT BEHIND
Hard parts are the bones
or the shells of an organism
F SSILS
BURIAL AND
FOSSILIZATION
FOSSILIZATION OCCURS WHEN
MINERALS REPLACE
ANY ORGANIC MATERIAL
TURNING IT INTO A FOSSIL ...
F SSILS
FOSSIL
F SSILS
TYPES OF FOSSILS
IMPRINTS
Occur when leaves andOccur when leaves and
feathers leave anfeathers leave an
impression...
F SSILS
TYPES OF FOSSILS
ORGANISMS GET TRAPPED
IN HARDENING TREE SAP
AND ARE PRESERVED AS
FOSSILS
AMBER
F SSILS
TYPES OF FOSSILS
ICE
SOME ORGANISMS
MAY BE PRESERVED AS
FOSSILS IN ICE
F SSILS
TYPES OF FOSSILS
TAR
ANIMALS GET
TRAPPED IN
TAR PITS AND
THEIR REMAINS
GET PRESERVED-
LA BREA TAR
PITS IN
CALIFORN...
F SSILS
TYPES OF FOSSILS
PETRIFIED
WOOD
PETRIFICATION OCCURS
WHEN MINERALS
DISSOLVED IN GROUND
WATER GRADUALLY
REPLACE THE...
F SSILS
WHAT DO FOSSILS TELL US?
APPEARANCE
AND ACTIVITIES
OF PAST LIFE
FOSSIL TEETH GIVE
US CLUES AS TO
WHAT THE ANIMAL
A...
F SSILS
WHAT DO FOSSILS TELL US?
SPECIES HAS
EVOLVED OR
CHANGED
F SSILS
WHAT DO FOSSILS TELL US?
EARTH’S PAST
CLIMATES
NYS
458 MILLION YEARS AGO 250 MILLION YEARS AGO
FOSSIL CORAL = WARM...
GE LOGIC TIME
The geologic time
scale is based on the
FOSSIL RECORD
LARGE
TIME
UNITS
SMALL
TIME
UNITS
EON
ERA
PERIOD
EPOCH
GE LOGIC TIME
Geologic History of
NYS- ESRT p. 8 & 9
Precambrian Eon
Archean
Proterozoic
Phanerozoic Eon
GE LOGIC TIME
Geologic History of
NYS- ESRT p. 8 & 9
Precambrian Eon
Archean
Proterozoic
Phanerozoic Eon
Cenozoic
Era
Meso...
GE LOGIC TIME
Phanerozoic Eon
Cenozoic
Era
Quartern
ary
Period
Mesozoic Paleozoic
Neogene Paleogene
GE LOGIC TIME
Cenozoic
Era
Quarterna
y Period
EARLY LIFE ON EARTH
Neogene Paleogene
Pleistocene Holocene
GE LOGIC TIMEGE LOGIC TIME
Why are the sections of
geologic time separated
this way?
Major
Extinctions Major Climate
Chang...
GE LOGIC TIME- Model of Geologic Time
Scale
Name of Era/Eon Millions of Years
Ago
Duration Percent of Earth’s
History
Ceno...
RELATIVE DATING
What is relative dating?
Determining the age of
something compared to
something else
NO NUMBER IS NEEDED!!...
RELATIVE DATING
Rules
for
Sequencing:
LAW OF SUPERPOSITION:
In undisturbed
sedimentary rock the
oldest layer is on the
bot...
RELATIVE DATING
Rules
for
Sequencing:
FAULTING:
A fault is younger
than the layers it
cuts across
Duh!!! Don’t the rock
la...
RELATIVE DATING
Rules
for
Sequencing:
IGNEOUS INTRUSION:
An igneous intrusion
is younger than the
rock layers it
penetrate...
RELATIVE DATING
Rules
for
Sequencing:
CONTACT METAMORPHISM:
The contact
metamorphism is
younger than the
layers it cuts th...
RELATIVE DATING
Rules
for
Sequencing:
Unconformity
A “missing” layer of rock.
buried erosional surface.
Rocks were
deposit...
RELATIVE DATING
Rules
for
Sequencing:
TILTING:
Tilting or folding of
rock layers is
younger than the
layers it affects
Relative Dating Instructions
Relative Time:
Ages of events are placed in order of
occurrence.
No exact date is identified....
Law of Uniformitarianism
• "The present is the key to the past."
• or what we see now has almost certainly
happened before...
Original Horizontality- Rocks are usually deposited
flat and level.
• You would say
– “Deposition of”
sandstone, limestone...
The law of cross-cutting relationships—an
igneous rock is younger than the rocks that
it has intruded into. This also appl...
Sequence 1: Uplift & Erosion
• Any time folding or tilting occurs
• UPLIFT will occur
• If there is uplift – EROSION will
...
Unconformity
• A “gap” in the rock
record where erosion
or non-deposition
occurred.
• You must include this
as a separate ...
•Layers are formed according to superposition.
Here’s How It Works!Here’s How It Works!
•Something happens to uplift the area-
(folding, faulting, etc).
•Erosion wears away the uppermost layers
•Area submerges (or sinks) and deposition
begins again.
Other Guidelines for figuring out a
sequence:
• Sedimentary rocks are usually formed
under water.
• Weathering and erosion...
Practice Sequencing
• Turn to page 7 in your notes.
• We will complete #1 together.
• Complete #2-#6 for homework, we will...
Practice Sequencing #3
8._________________________
7._________________________
6._________________________
5._____________...
Practice Sequencing #4
6._________________________
5._________________________
4._________________________
3._____________...
Practice Sequencing #5
7._________________________
6._________________________
5._________________________
4._____________...
Practice Sequencing #6
7._________________________
6._________________________
5._________________________
4._____________...
Rock Correlation
• Want to know what happened in Earth history in
widely different locations?
• Rock correlation -- hooks ...
Rock Correlation:
Matching up outcrops at
different locations
Volcanic Time
Markers
Index Fossils
Rock layers have:
Same c...
Outcrop 1 Outcrop 2 Outcrop 3 Outcrop 4
Correlating Rock Layers
Index Fossils
Short Lived
Wide Spread
Absolute Age
Examples
--65 Million Years Ago
--1990
What is absolute age?
Identifies the exact date
of an event
How can we figure it out?
Radio Active decay
Radioactive
(parent element):
Atom with an
unstable nucleus
that decays
Radioactive
(parent element):
Atom with an
unstable nucleus
that decays
Carbon 14: Carbon
Dating
Used to date organic rema...
Half-Life:
Time it takes for ½ of a
radioactive element
to decay into a stable
element
Is NOT affected by:
Heat Pressure
M...
Daughter Element:
Stable element, product
of radioactive decay
Geologic history academic
Geologic history academic
Geologic history academic
Geologic history academic
Geologic history academic
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Geologic history academic

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Geologic history academic

  1. 1. Geologic History
  2. 2. F SSILS WHAT ARE FOSSILS? the remains or trace of a oncethe remains or trace of a once living thing, usually preserved inliving thing, usually preserved in sedimentary rocksedimentary rock
  3. 3. F SSILS- How are they formed? ALIVE
  4. 4. F SSILS DEAD AND DECAYING
  5. 5. F SSILS HARD PARTS LEFT BEHIND Hard parts are the bones or the shells of an organism
  6. 6. F SSILS BURIAL AND FOSSILIZATION FOSSILIZATION OCCURS WHEN MINERALS REPLACE ANY ORGANIC MATERIAL TURNING IT INTO A FOSSIL (ROCK)
  7. 7. F SSILS FOSSIL
  8. 8. F SSILS TYPES OF FOSSILS IMPRINTS Occur when leaves andOccur when leaves and feathers leave anfeathers leave an impression in mud thatimpression in mud that later hardens into rock.later hardens into rock.
  9. 9. F SSILS TYPES OF FOSSILS ORGANISMS GET TRAPPED IN HARDENING TREE SAP AND ARE PRESERVED AS FOSSILS AMBER
  10. 10. F SSILS TYPES OF FOSSILS ICE SOME ORGANISMS MAY BE PRESERVED AS FOSSILS IN ICE
  11. 11. F SSILS TYPES OF FOSSILS TAR ANIMALS GET TRAPPED IN TAR PITS AND THEIR REMAINS GET PRESERVED- LA BREA TAR PITS IN CALIFORNIA
  12. 12. F SSILS TYPES OF FOSSILS PETRIFIED WOOD PETRIFICATION OCCURS WHEN MINERALS DISSOLVED IN GROUND WATER GRADUALLY REPLACE THE ORIGINAL TISSUES OF PLANTS AND ANIMALS
  13. 13. F SSILS WHAT DO FOSSILS TELL US? APPEARANCE AND ACTIVITIES OF PAST LIFE FOSSIL TEETH GIVE US CLUES AS TO WHAT THE ANIMAL ATE
  14. 14. F SSILS WHAT DO FOSSILS TELL US? SPECIES HAS EVOLVED OR CHANGED
  15. 15. F SSILS WHAT DO FOSSILS TELL US? EARTH’S PAST CLIMATES NYS 458 MILLION YEARS AGO 250 MILLION YEARS AGO FOSSIL CORAL = WARM CLIMATE
  16. 16. GE LOGIC TIME The geologic time scale is based on the FOSSIL RECORD LARGE TIME UNITS SMALL TIME UNITS EON ERA PERIOD EPOCH
  17. 17. GE LOGIC TIME Geologic History of NYS- ESRT p. 8 & 9 Precambrian Eon Archean Proterozoic Phanerozoic Eon
  18. 18. GE LOGIC TIME Geologic History of NYS- ESRT p. 8 & 9 Precambrian Eon Archean Proterozoic Phanerozoic Eon Cenozoic Era Mesozoic Paleozoic
  19. 19. GE LOGIC TIME Phanerozoic Eon Cenozoic Era Quartern ary Period Mesozoic Paleozoic Neogene Paleogene
  20. 20. GE LOGIC TIME Cenozoic Era Quarterna y Period EARLY LIFE ON EARTH Neogene Paleogene Pleistocene Holocene
  21. 21. GE LOGIC TIMEGE LOGIC TIME Why are the sections of geologic time separated this way? Major Extinctions Major Climate Change Appearance Of new life
  22. 22. GE LOGIC TIME- Model of Geologic Time Scale Name of Era/Eon Millions of Years Ago Duration Percent of Earth’s History Cenozoic Mesozoic Paleozoic Precambrian 0 to 65 65 to 251 251 to 544 544 to 4600 65 my 186 my 293 my 4056 my 1.4% 4% 6.4% 88.1%
  23. 23. RELATIVE DATING What is relative dating? Determining the age of something compared to something else NO NUMBER IS NEEDED!! THIS IS JUST LIKE SAYING: Trilobites are older than dinosaurs Dinosaurs are older than mastodonts We do this to determine how old rock layers are…
  24. 24. RELATIVE DATING Rules for Sequencing: LAW OF SUPERPOSITION: In undisturbed sedimentary rock the oldest layer is on the bottom, youngest on topYOUNGEST OLDEST
  25. 25. RELATIVE DATING Rules for Sequencing: FAULTING: A fault is younger than the layers it cuts across Duh!!! Don’t the rock layers need to be there in the first place?
  26. 26. RELATIVE DATING Rules for Sequencing: IGNEOUS INTRUSION: An igneous intrusion is younger than the rock layers it penetrates Remember igneous rocks form from magma. An igneous intrusion is when magma seeps up in between rock layers and hardens to form rock.
  27. 27. RELATIVE DATING Rules for Sequencing: CONTACT METAMORPHISM: The contact metamorphism is younger than the layers it cuts through When the magma seeps up between rock layers it is very hot and it bakes the rocks around it. The surrounding rocks do not melt but are metamorphosed. Duh again!!!! If there were no rock layers there then there wouldn’t be anything to turn into metamorphic rock.
  28. 28. RELATIVE DATING Rules for Sequencing: Unconformity A “missing” layer of rock. buried erosional surface. Rocks were deposited, erosion occurred at the surface and then new rock was deposited.
  29. 29. RELATIVE DATING Rules for Sequencing: TILTING: Tilting or folding of rock layers is younger than the layers it affects
  30. 30. Relative Dating Instructions Relative Time: Ages of events are placed in order of occurrence. No exact date is identified. Ex. WWI and WWII "I am the second child in my family."
  31. 31. Law of Uniformitarianism • "The present is the key to the past." • or what we see now has almost certainly happened before and therefore can be used for interpreting the past.
  32. 32. Original Horizontality- Rocks are usually deposited flat and level. • You would say – “Deposition of” sandstone, limestone, shale, etc. – This applies to sedimentary rocks ONLY
  33. 33. The law of cross-cutting relationships—an igneous rock is younger than the rocks that it has intruded into. This also applies to faults. You would say— “Igneous intrusion” or faulting/folding. 4. Faulting 3. Deposition of Shale 2. Deposition of Sandstone 1. Deposition of Limestone
  34. 34. Sequence 1: Uplift & Erosion • Any time folding or tilting occurs • UPLIFT will occur • If there is uplift – EROSION will occur
  35. 35. Unconformity • A “gap” in the rock record where erosion or non-deposition occurred. • You must include this as a separate step in the sequence of events.
  36. 36. •Layers are formed according to superposition. Here’s How It Works!Here’s How It Works!
  37. 37. •Something happens to uplift the area- (folding, faulting, etc).
  38. 38. •Erosion wears away the uppermost layers
  39. 39. •Area submerges (or sinks) and deposition begins again.
  40. 40. Other Guidelines for figuring out a sequence: • Sedimentary rocks are usually formed under water. • Weathering and erosion usually happen above water (on dry land).
  41. 41. Practice Sequencing • Turn to page 7 in your notes. • We will complete #1 together. • Complete #2-#6 for homework, we will go over them tomorrow.
  42. 42. Practice Sequencing #3 8._________________________ 7._________________________ 6._________________________ 5._________________________ 4._________________________ 3._________________________ 2._________________________ 1._____________________________
  43. 43. Practice Sequencing #4 6._________________________ 5._________________________ 4._________________________ 3._________________________ 2._________________________ 1._____________________________
  44. 44. Practice Sequencing #5 7._________________________ 6._________________________ 5._________________________ 4._________________________ 3._________________________ 2._________________________ 1._____________________________
  45. 45. Practice Sequencing #6 7._________________________ 6._________________________ 5._________________________ 4._________________________ 3._________________________ 2._________________________ 1._____________________________
  46. 46. Rock Correlation • Want to know what happened in Earth history in widely different locations? • Rock correlation -- hooks up rocks that look alike – The key bed – a particular strata that is very distinctive – Fossil correlation -- hooks up rocks that formed at the same time and relies on the following: • index fossils • Rock type (color and composition)
  47. 47. Rock Correlation: Matching up outcrops at different locations Volcanic Time Markers Index Fossils Rock layers have: Same color, and composition
  48. 48. Outcrop 1 Outcrop 2 Outcrop 3 Outcrop 4 Correlating Rock Layers
  49. 49. Index Fossils Short Lived Wide Spread
  50. 50. Absolute Age Examples --65 Million Years Ago --1990 What is absolute age? Identifies the exact date of an event
  51. 51. How can we figure it out? Radio Active decay Radioactive (parent element): Atom with an unstable nucleus that decays
  52. 52. Radioactive (parent element): Atom with an unstable nucleus that decays Carbon 14: Carbon Dating Used to date organic remains (woods, bones) no older than 50,000 years
  53. 53. Half-Life: Time it takes for ½ of a radioactive element to decay into a stable element Is NOT affected by: Heat Pressure Mass
  54. 54. Daughter Element: Stable element, product of radioactive decay

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