Transcript HISTORICAL_GEOLOGY_fossils

HISTORICAL GEOLOGY:
FOSSILS
How do fossils form?
What gets preserved?
• Fossils are the record of life preserved in
stone. Almost all living organisms can
leave fossils, but usually only the hard
parts of plants and animals fossilize.
• The soft part get yucky and do not get
preserved generally. There are some
exceptions.
Trace Fossils
• Trace Fossils include the footprints of
animals left in soft mud, later to be buried,
and turned into stone.
http://consumerincentivezone.com/?nc=1
Fossils Don’t Stink
• Under certain circumstances fossils of
animal dung, eggs, and even complete
nest with eggs have been preserved in
stone.
ABC of Fossil Preservation
• Fossils are formed in a number of different ways,
but most are formed when a plant or animal dies
in a watery environment and is buried in mud
and silt.
• Soft tissues quickly decompose leaving the hard
bones or shells behind.
• Over time sediment builds over the top and
hardens into rock.
• As the encased bones decay, minerals seep in
replacing the organic material cell by cell in a
process called "petrification."
Petrification
Mold Verse Cast
• Alternatively the bones may completely
decay leaving a cast of the organism. The
void left behind may then fill with minerals
making a stone replica of the organism
(mold).
http://people.uncw.edu/dockal/gly312/fossils/fossil2.jpg
http://www.gpc.edu/~pgore/myphotos/fossils/cast&mold.jpg
Sap to Amber
• Fossils can form in unusual ways. Small
bugs or insects can become trapped in
tree sap. Eventually the sap hardens and
forms the semiprecious material called
amber. In some pieces of amber the
entombed remains of organisms can be
found.
Let me Out of Here!!!!!
When your Hot your Hot!!!
• Volcanic eruptions can form fossils when
animals get trapped in the hot ash flows.
In this case, the fossil is a hole in the
shape of the animal.
http://www.msnucleus.org/membership/html/k-6/pt/hazards/3/images/pompeii.jpg
www.me.berkeley.edu
To the Sea, to the Sea, to the
Wonderful Sea.
• By far the most common fossil remains are
those of shelled invertebrate sea loving
creatures such as snails, corrals, and
clams. These make up most of the fossil
record.
http://oak.ucc.nau.edu/llc7/Photo%20Albums/Geology/slides/Cretaceous%20Marine%20Fossils.jpg
MARINE FOSSILS RULE
http://www.nhm.ac.uk/visit-us/galleries/lifegalleries/fossils-from-britain/index.html
www.lbl.gov
http://www.stonecompany.com/fossils/images/reptilez.JPG
http://www.langsfossils.com/sale-pics/marine/section-pics/marine-directory.jpg
http://www.nhm.ac.uk/visit-us/galleries/life-galleries/fossil-marine-reptiles/
Rare Finds
• Fossils of land animals are scarcer than those of
plants. In order to become fossilized, animals
must die in a watery environment and become
buried in the mud and silt. Because of this
requirement most land creatures never get the
chance to become fossilized unless they die
next to a lake or stream. Indeed there may be
whole species of land animals in which no fossil
record has been discovered. We may never
know how many and diverse these animals
were.
The Incomplete Record
http://www.blackwellpublishing.com/ridley/tutorials/Fossils_and_the_history_of_life22.asp
http://www.ucmp.berkeley.edu/carboniferous/carblife.html
Relative Time
• Telling relative
time simply
involves placing
events in a
sequence relative
to one another.
This sort of time
says nothing at
all about age in
years before the
present.
Geologic Column
•
• The geologic calendar
that we use to place
events in a sequence of
relative time is the
geologic column.
• The largest scale
division of time is
into two eons.
• Precambrian eon
(older)
• Phanerozoic eon
(younger)
ERAS
• Eons are divided into
eras.
• Archean (older
Precambrian)
• Proterozoic (younger
Precambrian)
• Paleozoic (oldest
Phanerozoic)
• Mesozoic (middle
Phanerozoic)
• Cenozoic (youngest
Phanerozoic)
•
PERIODS
•
• Eras are divided
into periods (see
column for
divisions)
• Periods are divided
into epochs (see
column for epochs
of the Tertiary
Period of the
Cenozoic Era
(Paleocene, Eocene,
etc.)
Absolute time
• Absolute time is
the age in years
before the
present of a rock
or a particular
geologic event. Ma
refers to millions
of years, and Ba
refers to billions
of years.
Absolute time
Absolute ages are
generally assigned to
events in the geologic
column by radiometric
dating of rocks formed
during the events.
Radiometric dating
depends upon the
constant rate of decay
of radioactive isotopes
to produce stable
daughter products.
During the decay
process, the isotope
gives off energy in the
form of subatomic
particles and radiation
generating heat.
Radioactive parent isotopes
and their stable daughter
products
Radioactive Parent
Stable Daughter
Potassium 40
Argon 40
Rubidium 87
Strontium 87
Thorium 232
Lead 208
Uranium 235
Lead 207
Uranium 238
Lead 206
Carbon 14
Nitrogen 14
Absolute time
Radioactive
Parent
Stable
Daughter
Half life
Potassium 40
Argon 40
1.25 billion yrs
Rubidium 87
Strontium 87
48.8 billion yrs
Thorium 232
Lead 208
14 billion years
Uranium 235
Lead 207
704 million
years
Uranium 238
Lead 206
4.47 billion
years
Carbon 14
Nitrogen 14
5730 years
• Basically, the geologist
measures the ratio of
parent isotope to
daughter isotope in a
rock, and knowing the
rate of decay to form
the daughter product,
is able to calculate an
age in years before
the present.
• For this procedure to
work, the rock must
be a closed system,
that is, no material
can have been added
or lost following the
formation of the rock.
Absolute
time
• Dates on igneous rocks
give the age of
crystallization
• Dates on metamorphic
rocks give the age of
the last metamorphic
event.
• Dates on sedimentary
rocks are meaningless
if they come from
minerals that
predated the
formation of the rock
(i.e., minerals in a
siliciclastic or
terrigenous rock).
P Daugh
ar
ter
en
t
t1/2
Useful Range
4.47
b.y
238
U
206Pb
235
U
207Pb
232
Th
208Pb
40
K
40Ar &
40Ca
1.28
b.y
>10,000 years
87
Rb
87Sr
48 b.y
>10 million
years
147
Sm
14
C
143
14N
Type of Material
707
m.y
>10 million
years
14 b.y
106
b.y.
5,730
y
Igneous &
sometimes
metamorphic
rocks and minerals
>10 million
years
100 - 70,000
years
Organic Material
Absolute time
•
Sedimentary rocks are
usually dated by knowing
their relationships to
igneous rocks of known age,
using superposition and
cross-cutting relationships.
Telling relative time
• Principle of
Superposition - In a
layered or stratified
sequence of rocks,
such as sedimentary
rocks or lava flows or
ash deposits, the
rock at the bottom
of the pile is the
oldest and rocks
successively higher in
the pile are
successively younger.
• http://www.classzone.
com/books/earth_scie
nce/terc/content/inves
tigations/es2903/es29
03page03.cfm
•
Principle of Original horizontality
•
http://creationwiki.org/images/9/9f/Strata_folds.jpg
• Layered or stratified
rocks are generally
deposited
horizontally.
• Departure from
horizontality generally
indicates some sort of
deformation, such as
tilting or folding.
• Deformation usually
occurs during
mountain building, but
gentle regional tilting
of rocks can occur
during regional uplift
of otherwise stable
parts of the continent
(the craton).
Cross-Cutting Relationships
When one body of rock,
such as a dike, cuts
across another rock,
such as a sequence of
layered sedimentary
rocks, the rocks
being cut are older
and the rock doing
the cutting is
younger.
This also applies to
situations where a
fault cut across
rocks. The rocks
being faulted are
older than the fault.
•
Principle of faunal succession
• Organisms
change or evolve
through time
•
and species do
not repeat
themselves
during this
evolution.
• Certain fossils
may be good
indicators of
certain intervals
of time. “INDEX
FOSSILS” http://www.indiana.edu/~geol105b/images/gaia_chapter_6/relative_age_determination.htm
Index fossils
• Index fossils enable
geologists to
correlate
sedimentary rocks.
Index Fossils are
fossils of organisms
that were...
• abundant
• geographically wideranging
• readily preserved
• lived a short period
of time
•
http://www.utexas.edu/tmm/npl/beachcombing/images/austin_group.jpg
• Unconformities and their significance
• an unconformity is a surface in the rock record along which rocks
are missing and time is therefore not recorded.
• the most obvious type of unconformity is an angular unconformity,
where rocks beneath the surface are more strongly deformed and
those above the surface are less strongly deformed.
• unconformities often represent an interval of mountain building,
where rocks are deformed, intruded by plutons and uplifted.
Erosion removes rocks from the uplifted region, and subsequent
subsidence (sinking) of the region is followed by deposition of
sediment atop the unconformable surface.
Principle of Uniformitarianism
• Principle of Uniformitarianism or Actualism
• This principle underlies all of the work we do in geology. This is
the way it works. Natural laws are unchanging. Therefore, the
way natural laws govern geologic processes that are operating
today is the same way that natural laws governed geologic
processes that operated in the past. We can therefore use our
understanding of present-day geologic processes to interpret
past geologic events.
• Sometimes this principle is paraphrased as "the present is the
key to the past", but be careful.
• Note, however, that the principle does not imply that past
rates of process, or conditions under which the processes
work, were the same as today. Nor does it imply that
Earth's processes work at constant or uniform rates.
Consequently, to avoid confusion, we often refer to the
principle of uniformitarianism as "actualism."
PRECAMBRIAN
• The Precambrian
record starts about 3.8
billion years ago and
lasted till 543 million
years ago. Most of
the earth’s history is
during the
Precambrian. Index
fossil is the
Stromatolite formed
from Cyan bacteria
and sediments in a
shallow waters near
shore.
http://3.bp.blogspot.com/_CqK2iKj3zjM/R1B8CWDzmrI/AAAAAAAAAMk/1wOk7RZtmHI/s1600R/Proterozoic-Stroms.jpg
CAMBRIAN the first Period in the
Paleozoic Era
Time of the Cambrian
Explosion– Many
different life form
suddenly developed
(Burgess Shale).
Index fossils is the
Trilobite.
Time: 543 to 490 Million
years ago.
http://users.path.ox.ac.uk/~wjames/Evolution/evolution4_files/slide0006_image035.jpg
http://science.nationalgeographic.co.in/staticfiles/NGS/Shared/StaticFiles/Science/Images/Content/trilobite-fossil422863-ga.jpg
ORDOVICIAN PERIOD
• Ordovician life
consisted of
brachiopods,
bryozoans,
Cephalopods,
gastropods,
echinoderms, corals
pelecypods and the
graptolites (Index
fossil). Time span 443
-490 million years
ago.
http://www.fossils-facts-and-finds.com/images/graptolite-250.jpg
http://www.museumwales.ac.uk/media/3/7/3/4/thumb_200/graptolite.jpg
SILURIAN PERIOD
• Silurian life is similar
to those found in the
Ordovician. Except a
new animal has
appeared. The
Eurypterid (sea
scorpion). Shallow
seas covering N.A.
begin to dry up. Large
deposits of Salt and
Gypsum develop.
http://geology.stlawu.edu/wp-content/uploads/eurypterid.jpg
Devonian Period
• Age of the Fishes
– Jawless fish like
lampreys, jawed fish
which were armored.
– First lungfish appears.
– Birth of the
Appalachian
Mountains occurs.
– Time 417 - 354 Million
years ago.
http://allhatnocattle.net/fossil-fish.jpg
http://www.fmnh.helsinki.fi/verkkonayttelyt/elamanhistoria/nayttelykuvat/devoni_kalafossiili.jpg
Carboniferous Period
or the Mississippian and
Pennsylvanian Periods
• Mississippian was when
the crinoids and
foraminifera made their
appearance.
• Pennsylvanian (Swamps)
was when the first reptiles
became the 1st land
animals.
• Time Miss- 354 – 323
million years ago.
• Time Penn- 324 – 290
million years ago.
http://www.fossilmall.com/EDCOPE_Enterprises/echinoderms/crinoids11/CK04B.jpg
http://www.kgs.ku.edu/Extension/fossils/gifs/fusul_draw.gif
Permian Period
• Time of wide spread
mountain building.
Pangaea has formed
• Nearly ½ of all known
animal groups have
become extinct. Diversity
of animals within a group
is greatly reduced.
• Survivors Cephalopods
and reptiles.
• Time 290 to 248 Million
years ago.
http://www.gc.maricopa.edu/earthsci/imagearchive/cephalopod.jpg
http://www.tucsonshow.com/reports/tucson2002/images/mvc-112x.jpg
Mesozoic Era-Triassic, Jurassic, and
Cretaceous Periods
• Triassic Period 248206 million years ago.
Index fossil is the
Ammonites part of the
Cephalopods. Plants
have invaded the land
including fern trees,
cycads, and conifers.
Pangaea is joined still
but has begun to split.
http://www.discoveringfossils.co.uk/ammonite_sutures2.jpg
Mesozoic Era-Triassic, Jurassic, and
Cretaceous Periods
• Jurassic Period- 206 to
144 million years ago.
• Large Dinosaurs roam
the earth, and some
smaller dinosaurs are
evolving into birds and
Insects are everywhere.
• Mammals make their first
appearance (rodent like)
http://ngm.nationalgeographic.com/2008/07/tyrannosaur-trap/gwin-text
Mesozoic Era-Triassic, Jurassic, and
Cretaceous Periods
• Cretaceous Period 144 to
65 Million years ago.
• Tyrannosaurus roamed
the earth along with many
other large meat eaters.
• The period comes to an
abrupt halt. Why, not
really known. Possible
Asteroid impact, causing
dust to block the sun.
What ever the cause 50
% of all plants and
animals were wiped out.
http://www.uky.edu/KGS/education/images/k_extinct.jpg
Cenozoic Era – Paleogene,
Neogene, and Quaternary Periods
• Cenozoic Era 65 million
years ago to recent.
• Paleogene Period 65 to
24 million years.
• Consist of the Paleocene,
Eocene, and Oligocene
Epoch.
• During the Paleocene the
western mountains are
forming. In the Eocene
coal in western NA is
forming. And during the
Oligocene the Alps and
Himalayas are rising.
• The Cenozoic Era
http://hoopermuseum.earthsci.carleton.ca/evolution/equidae/cenozoicera.html
Cenozoic Era – Paleogene,
Neogene, and Quaternary Periods
• Plaeogene Periodfossils indicate many
new species of
mammals.
http://www.paleocene.com/copyright/images/paleocene_forest.jpg
Cenozoic Era – Paleogene,
Neogene, and Quaternary Periods
• Neogene Period 24 to 2
million years ago.
• Consist of the Miocene,
and Pliocene Epochs.
• Mammals have made
great progress and are
the dominate large
organism.
• During the Pliocene Man
makes his entrance. The
climate is changing.
http://www.talkorigins.org/faqs/homs/dawn.gif
Cenozoic Era – Paleogene,
Neogene, and Quaternary Periods
• Welcome to the
Quaternary Period
which started about 2
million years ago and
continues thru today.
• If you haven’t noticed
Hominids have done
real well, and are now
the top dog so to
speak.
1 HOMO HABILIS ~ NICKNAME:
Handyman LIVED: 2.4 to 1.6 million years
ago HABITAT: Tropical Africa DIET:
Omnivorous – nuts, seeds, tubers, fruits,
some meat
2 HOMO SAPIEN ~ NICKNAME: Human
LIVED: 200,000 years ago to present
HABITAT: All DIET: Omnivorous - meat,
vegetables, tubers, nuts, pizza, sushi
3 HOMO FLORESIENSIS ~ NICKNAME:
Hobbit LIVED: 95,000 to 13,000 years ago
HABITAT: Flores, Indonesia (tropical) DIET:
Omnivorous - meat included pygmy
stegodon, giant rat
4 HOMO ERECTUS ~ NICKNAME: Erectus
LIVED: 1.8 million years to 250,000 to
30,000 years ago HABITAT: Europe and
Western Asia DIET: Relied heavily on meat,
such as bison, deer and musk ox
100,000 years ago HABITAT: Tropical to
temperate - Africa, Asia, Europe DIET:
Omnivorous - meat, tubers, fruits, nuts
5 PARANTHROPUS BOISEI ~ NICKNAME:
Nutcracker man LIVED: 2.3 to 1.4 million
years ago HABITAT: Tropical Africa DIET:
Omnivorous - nuts, seeds, leaves, tubers,
fruits, maybe some meat
6 HOMO HEIDELBERGENSIS ~
NICKNAME: Goliath LIVED: 700,000 to
300,000 years ago HABITAT: Temperate
and tropical, Africa and Europe DIET:
Omnivorous - meat, vegetables, tubers, nuts
7 HOMO NEANDERTHALENSIS ~
NICKNAME: Neanderthal LIVED:
The Family
Picture
http://www.theage.com.au/ffximage/2005/03/18/evolution_1903_wideweb__430x328,1.jpg
Cited
• http://www.scienceviews.com/dinosaurs/fo
ssilformation.html
http://www.winona.edu/geology/MRW/lecture5.ht
ml
http://facstaff.gpc.edu/~pgore/geology/geo102/ra
dio.htm
http://www.tulane.edu/~sanelson/eens211/radio
metric_dating.htm
http://websearch.cs.com/cs/img.jsp?img=http%3A%2F%2Fwww.theage.com
.au%2Fffximage%2F2005%2F03%2F18%2Fevolution_1903_wideweb__
__430x328%2C1.jpg