A typical rock formationib.berkeley.edu/courses/bio1b/evolutionfall11/pdfs/...A typical rock...

A typical rock formation

Relative dating: some principles to follow...

Wednesday, October 26, 11

Principle of superposition


Principle of original horizontality


Principle of lateral continuity


Principle of cross-cutting relationships


Principle of inclusions


Principles of unconformities (missing time)


Radiometric Age Dating• Uses unstable isotopes of naturally

occurring elements. The isotopes decay: they change into different elements or different isotopes of the same element.

• The rate of decay is known (has been measured in the laboratory) for a variety of isotopes.

• When igneous rocks form, there is 100% parent and 0% daughter isotopes in the rock.

• The ratio of the parent and daughter isotopes can be measured using a mass spectrometer.


Method Parent isotope

Daughter isotope Half life Dating range

Rubidium-strontium Rb-87 Sr-87 47 by 10m-4.6b

Uranium-lead U-238 Pb-206 4.5 by 10m-4.6b

Uranium-lead U-235 Pb-207 71.3 my 10m-4.6b

Thorium-lead Th-232 Pb-208 14.1 by 10m-4.6b

Potassium-argon K-40 Ar-40 1.3 by .1m-4.6b

Carbon-14 C-14 N-14 5730 y 100-100,000


1999 GEOLOGIC TIME SCALECENOZOIC MESOZOIC PALEOZOIC

AGE(Ma)

EPOCH AGE PICKS(Ma)

MAGNETICPOLARITY PERIOD

HIST

.

ANO

M.

CHRO

N.

5

10

15

20

25

30

35

40

45

50

55

60

65

QUATER-NARY PLEISTOCENE

MIO

CENE

OLI

GO

CENE

TRIA

SSIC

JURA

SSIC

CRET

ACEO

US PERM

IAN

DEVO

NIAN

ORD

OVI

CIAN

SILU

RIAN

MIS

SISS

IPPI

ANPE

NNSY

LVAN

IAN

CAM

BRIA

N*CA

RBO

NIFE

ROUS

EOCE

NEPA

LEO

CENE

PLIOCENEPIACENZIANL

0.011.8

3.65.3

7.1

11.2

14.8

16.4

20.5

23.8

28.5

33.7

37.0

41.3

49.0

54.8

57.9

61.0

65.0

E

L

E

L

M

E

L

M

E

E

L

ZANCLEANMESSINIAN

TORTONIAN

SERRAVALLIAN

LANGHIAN

BURDIGALIAN

AQUITANIAN

CHATTIAN

RUPELIAN

PRIABONIAN

BARTONIAN

LUTETIAN

YPRESIAN

DANIAN

THANETIAN

SELANDIAN

CALABRIANHOLOCENE

TERT

IARY

PALE

OG

ENE

NEO

GEN

E1 C1

C2

C2A

C3

C3A

C4

C4A

C6

C6A

C6BC6C

C7

C8C9

C10

C11

C12

C13

C15C16

C17

C18

C19

C20

C21

C22

C23

C24

C25

C26

C27

C28

C29

C7A

C5

C5A

C5B

C5C

C5DC5E

22A

3

3A

44A

5

5B

5A

5C

66A

6B

7

8

910

1112

13

1516

17

18

19

20

21

22

23

24

25

28

29

26

27

7A

6C

5D5E

AGE(Ma)

EPOCH AGE PICKS(Ma)

UNCERT.(m.y.)

MAGNETICPOLARITY PERIOD

HIST

.

ANO

M.

CHRO

N.

AGE(Ma)

EPOCH AGE PICKS(Ma)PERIOD

70

260

280

300

320

340

380

360

400

420

440

460

480

500

520

540

80

90

100

110

120

130

140

150

160

170

180

190

210

200

220

230

240

NEO

COM

IAN

LATE

EARLY N.W

.S.

LATE

EARLY

MIDDLE

LATE

EARLY

MIDDLE

MAASTRICHTIAN65

248252256260

269

282

296303

290

323327

342

354

364370

380

391

400

412417419423428

443449

458464470

485490

500506512516

495

520

543

71.3 1

83.585.889.093.5

99.0

112

121

127

132

137

144

151154

164

159

CAMPANIAN

TATARIANUFIMIAN-KAZANIAN

KUNGURIAN

ARTINSKIAN

SAKMARIAN

ASSELIANGZELIAN

KASIMOVIANMOSCOVIAN

BASHKIRIANSERPUKHOVIAN

VISEAN

TOURNAISIAN

FAMENNIANFRASNIANGIVETIAN

EIFELIAN

EMSIANPRAGHIAN

LOCKHOVIANPRIDOLIANLUDLOVIAN

WENLOCKIAN

LLANDOVERIAN

ASHGILLIANCARADOCIANLLANDEILIANLLANVIRNIAN

ARENIGIAN

TREMADOCIANSUNWAPTAN*STEPTOEAN*MARJUMAN*

DELAMARAN*DYERAN*

MONTEZUMAN*

SANTONIANCONIACIANTURONIAN

CENOMANIAN

ALBIAN

APTIAN

BARREMIAN

HAUTERIVIAN

VALANGINIAN

BERRIASIAN

TITHONIAN

KIMMERIDGIANOXFORDIANCALLOVIAN

BATHONIAN

BAJOCIAN

AALENIAN

TOARCIAN

PLIENSBACHIAN

SINEMURIAN

HETTANGIAN

NORIAN

RHAETIAN

CARNIAN

LADINIAN

ANISIAN

OLENEKIANINDUAN

C31

C32

C33

31

3233

M0M1

M5

M10M12M14M16

M18M20M22

M25

M29

M3

169

176180

195

190

202206210

221

234

227

248245242

111

4

4

4

5

67

7

8

8

88

8

8

888

9

9

9

9910

1

2

3

3

.2

311

RAPI

D PO

LARI

TY C

HANG

ES

PRECAMBRIAN

PRO

TERO

ZOIC

ARCH

EAN

AGE(Ma)

EON ERABDY.AGES(Ma)

750

900

1600

2500

3000

3400

3800?

1000

1250

1500

1750

2000

2250

2500

2750

3000

3250

3500

3750

LATE

EARLY

MIDDLE

LATE

EARLY

MIDDLE

L

L

M

E

E

E

E

D

C

B

A

L

L

L

M

30 C30

30 C30

C3434

543


Paleomagnetics

Earth has a dipole magnetic field, with the direction in line with the axis of spin.

When rocks form, they are permanently magnetized in the direction of the current magnetic latitude.


Plate Tectonics


Fossils


A fossil is any recognizable evidence of preexisting life.

Types of fossils: (1) Trace fossils (2) Preserved material

Fossils are our only direct evidence ofwhat organisms looked like in the past.

The fossil record is a biased one.


Where is the time?


Taphonomy: The study of the process of fossilization, from death of the organismto discovery by the paleontologist.


Types of biases in the fossil record

• Fossils with no hard parts are rarely preserved. Fossil record is mostly a record of shells and bones.

• Organisms that lived in areas where they are likely to be preserved.

• Time averaging of fossil beds.

• Post-mortem transport, scavenging,


Diatoms Foraminifera

Microfossils


“Invertebrates”


Vertebrates


Stromatolites


TransitionalForms


Basilosaurus hind leg


Ankle bones of the archaeocetes Rodhocetus (Eocene)on the left, a pronghorn (middle) and Artiocetus (right).Note the double-pulleyed astragalus. Other features in common are a notched cuboid and a prominent fibular facet.


Tiktaalik roseae (late Devonian)Wednesday, October 26, 11

Microfossils from the Apex Chert, North Pole, Australia

About 3.465 billion years old, resembling filamentous cyanobacteria


Stromatolite, North Pole deposits, Western Australia

about 3.5 billion years old


Extant stromatolite showing closeup of cyanobacteria


Proterozoic (2.5 bya to 544 mya). Evolution of organisms with oxygenic photosynthesis caused an increase in oxygen levels. Rising oxygen levels in the world’s oceans caused the formation of iron oxide, often preserved in the banded iron formation.


Eukaryotic milestones

• 2.7 bya: chemical traces of eukaryotic-type lipids in fossil organic matter (controversial).

• 2.1 bya: Grypania spiralis, the first fairly well-accepted fossil eukaryote

• 1.6-1.8 bya: origin of single-celled algae of unknown type, known as acritarchs


Grypania spiralis from Michigan


acritarch


A typical rock formationib.berkeley.edu/courses/bio1b/evolutionfall11/pdfs/...A typical rock...

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