How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for Lifetm

Home , Age (geology), Geomagnetic reversal, Magnetostratigraphy, Paleomagnetism

- - - - http:// . ). Earth’s Magnetic Field Earth’s somewhat analo magnetic field is Earth’s created by fluid mo tromagnetic current outer core due to Earth’s tion in the liquid The north and south magnetic rotation. rotational axis, poles are close to Earth’s the latter represented by the geographic North Pole and South Pole, but Magnetic from North and Magnetic South are offset true North and true South. field is dynamic and magnetic Earth’s The magnetic poles are not complex. In 2005, the north magnetic stationary. moving pole was at 82.7°N, 114.4°W, northwest at approximately 40 km/yr, was while the south magnetic pole (2001) at 64.7°S, 138.0°E (www.ngdc.noaa.gov/ seg/geomag/faggeom.shtml magnetic field episodi In addition, Earth’s a reversal Prior to cally reverses polarity. randomizes of the magnetic field, the field there may be and and becomes weaker, The pro- multiple poles for a short time. gous to a bar magnet, in that the field is a gous to a bar magnet, pole and a south pole. dipole with a north is induced by an elec The magnetic field - - - - www.geocities.com/CapeCanaveral/Lab/6488/magfield.html Figure 1. Earth’s magnetic field under “normal polarity”. The arrows magnetic field under “normal polarity”. Figure 1. Earth’s depicting magnetic lines of force would be oriented in the opposite direction with a reversed field (reversed polarity). Figure from - - How Old Is It? Old Is How Part 2 – Magnetostratigraphy Part nature preserved in sediments or oceanic nature preserved in sediments or the crust (basalt) that can tell us about magnetic field changing nature of Earth’s through time. are The magnetic signal that geoscientists natural interested in measuring is called This remanent magnetization (NMR). signal is carried by magnetic minerals The NMR is preserved such as magnetite. past in basalt as it cools and crystallizes the the Curie temperature (~580°C for as mineral magnetite), or in sediments accumu detrital magnetic mineral grains Introduction the strati- In addition to biostratigraphy, the episodic reversals graphic record of is another tool to magnetic field of Earth’s and provide age establish a stratigraphy crustal rocks, intru information for cored This sequences. sions, and sedimentary of the magnetic sig is just one attribute situations, the In both late on the seafloor. with magnetic minerals become aligned magnetic field at the time of the Earth’s respectively. deposition, and crystallization a mag Not all rocks are good carriers of ing rock, while granite, a typical igneous rock of continental crust, is generally poor in magnetic min erals. Likewise, marine sediments composed of terrigenous silt and clay derived from the erosion of continental rocks have a much higher concentration of detrital magnetic mineral grains than does a pure biogenic sediment, such as calcareous or siliceous ooze. magnetic Describe the Earth’s field. What are the key features or characteristics of our A sketch may magnetic field? help. netic signal. The basalt that makes up netic signal. oceanic crust is a magnetite-bear

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PLEISTOCENE PLIOCENE MIOCENE

early late middle late middle Age 6 2.58 late 2 4 5 0.78 3.58 5.23 1.77 1 3 Jaramillo Cobb Mountain Olduvai Mammoth Cochiti Kaena Sidufjall Reunion Nunivak Thvera Chron, 2.150 subchron 4.620 4.290 4.890 4.480 4.180 3.330 3.220 3.040 3.110 0.990 1.070 1.211 1.770 1.950 2.140 4.980 5.230 4.800 1.201 BRUNHES MATUYAMA GAUSS GILBERT 2.581 5.890 3.580 0.780 Polarity r r n r n r n r 1r 2r r r r n n n n n 1n 1 2n 1 2r 1 2r 1 2 3n 1 2 3 4n Chron, C3Ar subchron C3r C3An C3n C1n C1r C2n C2r C2An C2Ar The Nature of the Earth’s Magnetic Field as Field Magnetic of the Earth’s Nature The Rocks and Sediments in Recorded pre directions typically two ancient field There are containing igneous rocks sedimentary or served in field of the magnetic reversal A minerals. magnetic in these directions. an abrupt change is seen as field direc- the affects over time also Plate motion in rocks. Inclination, or magnetic tions preserved angle of magnetization into or dip, represents the (Figures 1 and 3). surface out of the Earth’s of force are directed into the The magnetic lines Hemisphere (positive down), Earth in the Northern of the Earth in the Southern and directed out up; magnetic field is oriented Hemisphere (positive magnetic field (= words, today’s upwards). In other 2 ) ARTY - - P 1149 Inclination (° ITE CIENTIFIC S The inclinations of lithologic Unit I (Cores 185-1149A-1H through 13H) compared to the late the to compared 13H) through 185-1149A-1H (Cores I Unit lithologic of inclinations The 4, S 0

20 40 60 80 -90 -50 0 +50 +90 +50 0 -50 -90 Depth (mbsf) Depth 120 100 HAPTER HIPBOARD S C Figure F66. Figure 1995). al., et (Berggren scale time polarity magnetic Cenozoic for additional informa for additional - - . Figure 2a. Interpreted paleomagnetic in stratigraphy from Site 185-1149 the northwest Pacific (31°20.095’N, 143°21.805’E; 5817 m water depth). http://www-odp.tamu.edu/ publications/185_IR/chap_04/c4_f66. htm#573212 Activity depict the magnetic character The figures below sediment of two deep-sea (Fig- cores. Site 1149 ure 2a) is located in the northwest Pacific (~31°N latitude) near the Marianas (Fig- 1172 Site Trench. ure 2b) is located in the southwest Pacific (~44°S Tasmania. latitude) near Both records have been interpreted by correlating to the late Cenozoic Geomag tion about Earth’s magnetic field. magnetic field. tion about Earth’s field (paleomagnetism) is The ancient magnetic and sediments using a magne measured in rocks See http://www-odp.tamu.edu/sciops/labs/ tometer. of how shipboard pmag/ for a detailed discussion are collected. paleomagnetic data Scale Time netic Polarity (Berggren et al., 1995; Cande and Kent, 1995). Make a list of observations about the paleo magnetic record in these two deep-sea sediment sequences. How are they and how are they similar, different? cess is geologically rapid, taking several thousand thousand several rapid, taking is geologically cess polarity reverse completely field to for the years is referred to as field Today’s again. and stabilize of The last reversal 1). polarity” (Figure “normal 780,000 approximately field occurred the magnetic Refer to http://www.ngdc.noaa.gov/seg/ years ago. geomag/faqgeom.shtml#q1

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org

No recovery recovery No Reverse polarity polarity Reverse Normal polarity polarity Normal

9 90 0 -90 90 0 -90 90 0 -90

107.4 6.56

C3An.2n

105.4 6.26

100

100 100.75 6.13

C3An.1n

94.1 5.89

80 80

78.9 5.23

C3n.4n

4.62 66.6

C3n.2n

63.4 4.48

60 http://www-odp.tamu.edu/publications/189_IR/ 60 4.29

C3n.1n

Depth (mbsf) Depth 57.8 4.18

46.25

3.58

C2An.3n

41.7 3.33

40 40

3.22 40.2

C2An.2n

38.6 3.11

36.9 3.04

C2An.1n

30.9 2.58 .

20 20

19.55

1.75

C2n

17.1 1.77

ARTY 0.78 12.5

P C1n

1172 0 0

Figure 2b. Interpreted paleomagnetic stratigraphy from Site 189-1172 in the southwest Pacific Figure 2b. Interpreted paleomagnetic stratigraphy from Site 189-1172 (43°57.575’S, 149°55.701’E; 2622 m water depth). From chap_07/c7_f16.htm#382526

10 10 10 10 10 10 10 10 10

(mbsf)

ITE (Ma) -4 -6 -2 -6 -2 -4 -2 -4 CIENTIFIC -6

° ° ° Depth Age Polarity ) Intensity (mA/m) Intensity ) ( Inclination ) Intensity (mA/m) Intensity ) ( Inclination ) Intensity (mA/m) Intensity ) S ( Inclination

7,S Hole 1172A Hole Hole 1172B Hole Hole 1172C Hole

netostratigraphy.

Figure F16. Figure Long-core measurements from 0 to 100 mbsf for Holes 1172A, 1172B, and 1172C showing inclination, intensity, and interpreted ma interpreted and intensity, inclination, showing 1172C and 1172B, 1172A, Holes for mbsf 100 to 0 from measurements Long-core HAPTER g- HIPBOARD S C

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org ------Ships towing magnetometers across the ocean the ocean across magnetometers towing Ships patterns era recorded the post-WWII during basins relative to intensity and lesser magnetic of greater and negative mag These positive field. the present netic anomalies represent linear bands of alternat linear bands of represent netic anomalies axis to the spreading that trend parallel ing polarity side of on the opposite image pattern with a mirror correspond with The positive anomalies the ridge. as today which amplifies the a magnetic polarity while the negative anomalies magnetic intensity, which partially a reversed polarity, correspond with influence of the present-day field. dampens out the led to a test of the seafloor These observations Matthews, 1963; and (Vine spreading hypothesis and Hess advanced by Dietz (1961) 1963) Morley, et al. (1968) created the first (1962). Heirtzler a single marine magnetic GPTS by correlating Atlantic to radio anomaly profile from the South sequences. metrically dated terrestrial reversal the prominent For the Late Cretaceous to present, to positive anomalies (i.e., those corresponding geomagnetic time intervals, or chrons, of normal Chron 1n in the polarity) have been numbered from to Chron 34n central axis of the spreading centers Long Normal at the younger end of the Cretaceous Zone; 83.5 Ma). (also called the Cretaceous Quiet number refers to The suffix “n” after the anomaly to reversed polar and the “r” refers normal polarity, Many of the younger chrons are divided into ity. shorter polarity intervals, or subchrons. anomalies The GPTS based on marine magnetic Jurassic extends back through the late Middle Kent and Grad (Callovian stage, ~162 Ma; e.g., eous microfossil datum events (calcareous nan nofossil and planktic foraminifera) and zonations to the GPTS, which serves as the modern stan- dard for biochronology of the past 65 million years Astrochronologic calibration (“orbital (Figure 6). tuning”) of the GPTS polarity boundaries based on Milankovitch cyclicity in continuous marine sec tions with excellent magneto- and biostratigraphy has been applied to the Pliocene and Pleistocene (Berggren et al., 1995, and references therein) and older Neogene sequences (e.g., Gradstein, Ogg, stein, 1986), while land-based polarity records go stein, 1986), while land-based polarity (e.g., Gradstein et al., Triassic back through the nomenclature called the “M-sequence” A 1995). is used for marine magnetic polarity chrons of the Early Cretaceous to late Middle Jurassic extending from Chron M0r at the base the Cretaceous Long Aptian stage in the Normal (Chron 34n; base of the Early Cretaceous, ~121 Ma) to Chron M39 in the Jurassic (Callovian stage). Berggren et al. (1995) correlated Cenozoic calcar 4 ------). for a discussion of magnetic Development of the Geomagnetic Polarity Time Development of the Geomagnetic Polarity Time Scale (GPTS) Sequences of magnetic reversals measured in deep-sea cores can be correlated with the Geo Scale (GPTS) in order to Time magnetic Polarity determine the age and sedimentation history of a Time The Geomagnetic Polarity drill site (Figure 5). Scale is based on the marine magnetic anomaly Atlantic Ocean, sequence recorded in the South which has then been compared with other ocean basin sequences (Cande and Kent, 1992, 1995). This is the currently accepted GPTS for the later part of the Cretaceous Period and Cenozoic Era (0-84 Ma; Ma = mega-annums). Nine radiometric age tie points, plus the zero-age ridge axis, are used to calibrate this part of the timescale (ages for the marine magnetic anomalies between the calibration points are interpolated by a cubic spline function; Berggren et al., 1995). overprinting and what demagnetization techniques overprinting and what demagnetization from deep-sea are used to remove this overprint cores (http://www.oceanleadership.org/learning/ classroom/lab_briefs.html ing the Paleomagnetism Laboratory aboard the ing the Paleomagnetism Laboratory JOIDES Resolution leomagnetic studies. However, near the equator, near the equator, leomagnetic studies. However, declination data paleomagnetists rely heavily on See the Integrated because inclination is so low. describ Ocean Drilling Program (IODP) document tion at the north and south magnetic pole, ~0° at magnetic pole, north and south tion at the in between. and intermediate values the equator, of to determine the paleolatitude Inclination is used the rocks and sediments at igneous or sedimentary or deposition. time of crystallization is the angle between true Declination, or azimuth, trace of the magnetic field north and the horizontal (Figure 4). It represents the direc for your location field is in a northerly (today’s tion of magnetization whereas during a reversed field, direction (+/- 0°), direction the declination would be in a southerly determined on (+/- 180°). Declination can only be during cor sediment cores that have been oriented magnetic field ing with respect to the present day tool. Tensor using the collected on The inclination and declination data to determine rock or sediment cores can be used or paleomag the ancient polarity of the earth, used for pa netism. Inclination data are widely tion in the Northern Hemisphere, and by negative by negative and Hemisphere, in the Northern tion Hemisphere. in the Southern inclination of force are the magnetic lines equator, Near the - magnet way, surface. In this the Earth’s parallel to inclina of latitude; ~90° is a function ic inclination “normal polarity”) is represented by positive inclina by positive represented is polarity”) “normal

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org , Nature, The Geology of , Geological Society of America, p. America, Society of , Geological 199:947-949. reversals, and motions of the ocean floor and floor and ocean of the motions and reversals, Research of Geophysical Journal continents. 73:2119-2136. A.F. of in Honor Volume A Studies, Petrologic Buddington 599-620 In, sic to recent chronology. Atlantic Region, North America, Western North America, p. of M, Geological Society Volume 45-50. over oceanic ridges. netic anomalies Activity by University Kristen St. John, James Madison ([email protected]), and R. Mark Leckie, University of Massachusetts- Amherst ([email protected]). by Leckie Adapted from School of Rock materials and St. John, 2005. History of the ocean basins. In, the ocean basins. 1962. History of Hess, H.H., Juras- A 1986. F.M., and Gradstein, Kent, D.V., 1963. Mag- and Matthews, D.H., F.J., Vine, 5 ------A Journal , SEPM . International . Cambridge Univer , 100:6093-6095. , SEPM (Society for Journal of Geophysical , 97:13,917-13,951. and Aubry, M.-P., 1995. A revised Cenozoic revised A 1995. M.-P., Aubry, and In, geochronology and chronostratigraphy. Scales, and Global Time Geochronology, Stratigraphic Correlation 54, Sedimentary Geology) Special Publication p. 129-212. Late Cre magnetic polarity time scale for the taceous and Cenozoic. Research bration of the geomagnetic polarity timescale bration of the geomagnetic polarity for the late Cretaceous and Cenozoic. of Geophysical Research man, W.C., III, and LePichon, X., 1968. Ma man, W.C., rine magnetic anomalies, geomagnetic field enbol, J., Van Veen, P., Thierry, J., and Huang, Thierry, P., Veen, enbol, J., Van Jurassic, and Cretaceous Triassic, A Z., 1995. Scales, Time time scale. In, Geochronology, and Global Stratigraphic Correlation (Society for Sedimentary Geology) Special Publication 54, p. 95-126. Scale 2004 2004. Geologic Time Cambridge Uni Commission on Stratigraphy, Scale 1989 Geologic Time sity Press, 263 p. versity Press, 500 p. A.G., and Smith, D.G., 1990. L.E., Smith, evolution by spreading of the sea floor. Nature, floor. evolution by spreading of the sea 190:854-857. Cande, S.C., and Kent, D.V., 1992. A new geo A 1992. Cande, S.C., and Kent, D.V., References C.C., III, Swisher, Kent, D.V., Berggren, W.A., pretations (correlation to the Geomagnetic Polarity to the Geomagnetic Polarity pretations (correlation These 7 and 9. are shown in Figures Timescale) age control for the two data provide excellent Age-depth plots based on the paleomagnetic sites. Age- shown in Figures 8 and 10. reversal ages are to quantify and graphically depth plots are used rate history of the sites. depict the sedimentation Cande, S.C., and Kent, D.V., 1995. Revised cali 1995. Cande, S.C., and Kent, D.V., land et al. timescale (Gradstein, Ogg, Smith et al., Ogg, Smith timescale (Gradstein, land et al. ). 2004; http://www.stratigraphy.org from data collected of paleomagnetic Examples Program sites and their inter two Ocean Drilling graphic has published the latest time scale for the latest time scale has published the graphic Har succeeds the 1989 Eon, which Phanerozoic Smith et al., 2004, and references therein). More More therein). references 2004, and et al., Smith on Strati Commission International the recently, Gradstein, F.M., Ogg, J.G., Smith, A.G., et al., Ogg, J.G., Smith, Gradstein, F.M., J.R., Dickson, G.O., Herron, E.M., Pitt Heirtzler, Harland, W.B., Armstrong, R.L., Cox, A.V., Craig, A.V., Armstrong, R.L., Cox, Harland, W.B., Gradstein, F.M., Agterberg, F.P., Ogg, J.G., Hard Ogg, Agterberg, F.P., Gradstein, F.M., Dietz, R.S., 1961. Continent and ocean basin Dietz, R.S., 1961. Continent and

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org ) 6 (http://www.ngdc.noaa.gov/seg/geomag/icons/wmm2000i.gif Inclination in the Earth’s magnetic field. Figure 3. Inclination in the Earth’s

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org ) 7 (http://www.ngdc.noaa.gov/seg/geomag/icons/WMM-00D.gif Declination in Earth’s magnetic field. magnetic Figure 4. Declination in Earth’s

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 43 Age (Ma) 1.770-1.950 2.140-2.150 0.990-1.070 0.990-1.070 3.040-3.110 3.220-3.330 4.180-4.290 4.480-4.620 4.800-4.890 4.980-5.230 5.894-6.137 6.269-6.567 8.225-8.257 6.935-7.091 7.341-7.375 7.432-7.562 7.650-8.072 13.703-14.076 14.178-14.612 8.699-9.025 9.740-9.880 9.920-10.949 14.800-14.888 15.034-15.155 16.014-16.293 16.327-16.488 16.556-16.726 9.230-9.308 9.580-9.642 11.052-11.099 11.476-11.531 11.935-12.078 12.148-12.401 12.991-13.139 13.302-13.510 12.678-12.708 12.775-12.819 Jaramillo Mountain Cobb C2n Olduvai Reunion Kaena Mammoth Cochiti Nunivak Sidufjall Thvera C5An.1n C5An.2n C5AAn C5ABn C5ACn C5ADn C4r.1n C4An C5n.1n C5n.2n C5r.1n C5r.2n C5Bn.1n C5Bn.2n C5Cn.1n C5Cn.2n C5Cn.3n C3An.1n C3An.2n C3Bn C3Br.2n C4n.1n C4n.2n C4Ar.1n C4Ar.2n C5Ar.1n C5Ar.2n Polarity event Polarity 8 OTES N

Polarity ARTY

Chron C5n C4Ar C2Ar C5Cr C1n C5Br C3An C5An C5ADn C5r C1r C3Bn C5Cn C4An C5Bn C4r C2An C5Ar C4n C3n C2r C2n C3r P C4 C5 C5B C5A C3B C5C C4A C3A Epoch C5AA C5AB C5AC C5AD 0.78 Ma 3.58 Ma 2.581 Ma 14.800 Ma 14.800 11.935 Ma 11.935 5.894 Ma 6.935 Ma 7.432 Ma 8.699 Ma 9.740 Ma Gilbert XPLANATORY Gauss Magnetic 16.014 Ma 16.014 Brunhes CIENTIFIC

Matuyama

Miocene Miocene to Holocene geomagnetic polarity time scale (GPTS). In the polarity column, black = Pleistocene Pliocene late Miocene late middle Miocene middle 2, E Epoch

1 8 2 3 4 5 6 0 9 7

11 14 12 Age (Ma) Age 15 16 17 13 10 HAPTER HIPBOARD volume, Explanatory Notes chapter, (http://www-odp.tamu.edu/publications/191_IR/chap_02/ volume, Explanatory Notes chapter, ) S C Figure F6. F6. Figure are terminology chron magnetic and periods, geologic ages, Absolute polarity. reversed = white and normal GPTS. and(1995b) Kent (1995) and al. Cande et Berggren is based on the This figure left. at shown chap_02.htm Figure 5. Geomagnetic Polarity Time Scale (GPTS) for 17-0 Ma. In the polarity column, black = normal and Scale (GPTS) Time Figure 5. Geomagnetic Polarity periods, and magnetic chron terminology are shown at left. Absolute ages, geologic white = reversed polarity. Leg 191 From ODP This figure is based on the Berggren et al. (1995b) and Cande and Kent (1995) GPTS. Initial Reports

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 53 C4n C4r C4An C4Ar C5n C5r C5An C5Ar C2Ar C3n C3r C3An Polarity Inclination (°) -80 -40 0 40 80 Activity a list of observations Figure 4. Make Examine magnetic field Earth’s character of the about the last 17 million years. over the 50 9 100 150 200 250 300 - C2n C2An K M C1n J CM C1r C2r - Polarity ARTY P Inclination (°) 1208 ITE CIENTIFIC S after Inclination AF at peak demagnetization fields of 20 mT as measured with the shipboard 4, S -80 -40 0 40 80 0 50

150 100 HAPTER (mbsf) Depth HIPBOARD S C pass-through magnetometer at Hole 1208A. The column at the right of each plot shows interpreted zones of normal (black) and reversed (white) polarity. Gray intervals downsectionindicate zones farther zones in which polarity no certain polarity and inter- section the of top the at zones Polarity possible. is pretation are tentatively correlated to polarity chrons. Figure F19. Figure Use Figure 4 to interpret the paleomagnetic stra the paleomagnetic 4 to interpret Use Figure tigraphy (chrons and subchrons) recorded at Site recorded (chrons and subchrons) tigraphy Pacific (Shatsky in the northwest 1208 (below) if you must you make assumptions Rise). What pre reversal pattern the magnetic simply correlate with the Geomagnetic Polarity served in Site 1208 4? Scale shown in Figure Time Interpreting the Paleomagnetic Record Record the Paleomagnetic Interpreting Sediments Deep-Sea in Preserved

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 45 p. 54, T2, p. 52, T1, - "] Gephyrocapsa (1.71) [= B "G. oceanica B Nicklithus amplificus (6.84) B Globoconella conomiozea (7.12) B Amaurolithus primus (7.39) B Discoaster berggrenii (8.28) B Discoaster loeblichii (8.43) B Globorotalia plesiotumida (8.91) T Discoaster hamatus (9.63) T Catinaster calyculus (9.64) T Catinaster coalitus (9.69) B Neogloboquadrina acostaensis (9.89) T paracme Reticulofenestra pseudoumbilicus (7.29) B Hirsutella cibaoensis (7.91) B paracme Reticulofenestra pseudoumbilicus (8.79) B Globigerinoides extremus (8.94) B Hirsutella juanai (9.75) B Sphaeroidinella dehiscens s.l. (4.94) B Tuborotalia humilis (5.84) B Globigerinoides conglobatus (5.84) B Hirsutella margaritae (5.99) (0.26) B Emiliania huxleyi lacunosa (0.46) T Pseudoemiliania (0.61) T Globorotalia tosaensis (1.05) B Gephyrocapsa parallela G.] [= reentrance medium T large Gephyrocapsa spp. (1.24) T Globigerinoides obliquus (1.3) T Globigerina apertura (1.68) B medium T Globigerinoides extremus (1.91) T Discoaster brouweri (1.95) B Globorotalia truncatulinoides (2.03) T Pulleniatina finalis (2.05) T Globoturborotalia woodi (2.30) T Menardella miocenica (2.38) T Discoaster pentaradiatus (2.52) T Discoaster surculus (2.63) T Globigerina decoraperta (2.70) T Discoaster tamalis (2.83) T Menardella multicamerata (2.95) T Dentoglobigerina altispira (3.02) T Sphaeroidinellopsis seminulina (3.18) B Globorotalia tosaensis T Menardella miocenica (3.48) T Pulleniatina primalis (3.65) T Sphenolithus spp. (3.66) T Reticulofenestra pseudoumbilicus (3.80) T Neogloboquadrina acostaensis (3.83) T Hirsutella margaritae (3.88) T Globorotalia plesiotumida (4.15) T Hirsutella cibaoensis (4.16) B Globorotalia crassaformis (4.31) T Globoturborotalita nepenthes (4.37) T Amaurolithus spp. (4.56) T Ceratolithus acutus (5.05) B Ceratolithus rugosus (5.10) T Triquetrorhabdulus rugosus (5.23) B Ceratolithus acutus (5.37) T Discoaster quinqueramus (5.54) B Globorotalia tumida (5.96) T Nicklithus amplificus (6.00) T Fohsella lenguaensis (6.00) NN9 NN17 NN21 NN20 NN19 NN18 NN16 NN12 NN11 NN10 NN13-15 B = Base CN7 CN11 CN8b CN15 CN14 CN9a CN8a T = Top T = CN10c CN10b CN10a CN12d CN13b CN13a CN9bA CN9bB CN9bC CN12b+c CN12aB CN12aA rmation and references are given in Tables Tables in given are references and rmation ) 10 b a b a PL6 PL2 PL5 PL1 M14 M12 PL3+4

PT1 M13

Foraminifers Nannofossils Datum events volume, Explanatory Notes chapter, (http://www-odp.tamu. volume, Explanatory Notes chapter,

Pleistocene + Holocene + Pleistocene Gelasian Piacenzian Zanclean Messinian Tortonian

OTES

Age

N late -

late early late middle early ARTY middle

Miocene Pliocene Pleistocene Epoch 5.33 1.81 XPLANATORY CIENTIFIC 2 1 2 1 1 2 1 2 3 4 1 2 1 2 1 1 2 1 2 1 2 3 3 3 S Calcareous nannofossil and planktonic foraminiferal zonation used during Leg 208. References 208. Leg during used zonation foraminiferal planktonic and nannofossil Calcareous 2, E Chron C2r C4r C3r C1r C5n C3Bn C2n C1n C4n C3n C4Ar C3Ar C3Br C2Ar p. and CK95 = Cande occurrence. BC of = common bottom 57. TC occurrence, = of top common C2An C4An C3An Figure 6.(page 1 of three pages) Integration of biostratigraphy and magnetostratigraphy. Cal- Figure 6.(page 1 of three pages) Integration of biostratigraphy and magnetostratigraphy. Leg 208. Use this careous nannofossil and planktonic foraminiferal zonation used during ODP as a reference for the exercise that follows. References are cited in the text for each microfos edu/publications/208_IR/chap_02/chap_02.htm sil group. Shaded bands with dashed lines indicate that the zonal boundaries are not clearly sil group. Shaded bands with dashed lines indicate that the zonal boundaries are not clearly TC = = top, or last occurrence (LO) datum; B = base, or first occurrence (FO) datum; T delimited. Kent, 1995. top of common occurrence, BC = bottom of common occurrence. CK95 = Cande and Leg 208 Initial Reports From ODP T3, 0 1 2 3 4 5 6 7 8 9

10 HAPTER (Ma) Age HIPBOARD S C Figure F4. Figure are cited in the text for each microfossil group. Shaded bands with dashed info All lines delimited. indicate clearly that not are the boundaries zonal and Kent, 1995. (Continued on next four pages.) four next on (Continued 1995. Kent,

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 46 BC = Base common Discoaster deflandrei (15.6) B Discoaster hamatus (10.48) B Catinaster coalitus (10.79) TC Discoaster kugleri (11.60) BC Discoaster kugleri (11.88) B Triquetrorhabdulus rugosus (12.81) TC Cyclicargolithus floridanus (13.19) T Sphenolithus heteromorphus (13.55) T Helicosphaera ampliaperta (15.03) B Discoaster signus (15.6) B Sphenolithus heteromorphus (17.76) T Sphenolithus belemnos (17.89) B Sphenolithus belemnos (18.92) T Triquetrorhabdulus carinatus (19.6) T Fohsella fohsi s.l. (11.91) B Menardella archeomenardii (13.92) B Praeorbulina circularis (15.15) T Acme B Praeorbulina glomerosa (16.16) B Praeorbulina sicana (16.86) T Catapsydrax dissimilis (17.51) B Globigerinatella insueta s.s. (17.57) T Paragloborotalia mayeri (10.70) B Globoturborotalita nepenthes (11.64) B Fohsella fohsi s.l. (13.33) T Globoquadrina binaiensis (19.08) B Globoquadrina binaiensis (19.98) B Fohsella robusta (12.85) B Fohsella peripheroacuta (14.02) T Praeorbulina circularis (14.58) T Praeorbulina sicana (14.63) B Orbulina spp. (14.71) B Menardella archeomenardii (16.16) Menardella praemenardii (10.09) T Menardella praemenardii (10.43) T Paragloborotalia sikaensis (10.45) B Discoaster neohamatus Discoaster bellus gr. (10.48) T Coccolithus miopelagicus (11.02) B Globigerina apertura (11.06) T Globigerina decoraperta (11.46) T Clavatorella bermudezi (12.02) T Hirsutella praescitula (13.73) T Fohsella peripheroronda (13.92) B Menardella praemenardii (13.95) TC = Top common NN3 NN2 NN9 NN8 NN7 NN6 NN5 NN4 B = Base CN4 CN3 CN2 CN7 CN6 CN1c CN5b CN5a b a 11 s.s. = senso stricto s.l. = senso lato T = Top M9 M7 M6 M4 M3 M2 M8 M12 M11 M10 M5

Foraminifers Nannofossils Datum events

Langhian Burdigalian Tortonian Serravallian

Age OTES

early middle N late ARTY

P Miocene Epoch XPLANATORY 2 2 3 2 1 2 1 2 3 1 1 1 2 3 CIENTIFIC S Chron C6r C6n C5Er C5r 2, E C5ACr C5En C5Dr C5n C5Br C5Bn C5Cr C5Ar C5AAr C5ABr C5Dn C5ADr C5AAn C5ABn C5ADn C5ACn C5An C5Cn Figure 6, page 2.

10 11 12 13 14 15 16 17 18 19 20 HAPTER (Ma) Age HIPBOARD S C Figure F4 (continued). F4 Figure

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 47 BC = Base common B Increase Ericsonia obruta (33.7) T Sphenolithus delphix (23.07) B Sphenolithus delphix (23.33) B Sphenolithus disbelemnos (22.67) B Discoaster druggii (22.82) T Sphenolithus ciperoensis (24.33) 24.79) T Acme Cyclicargolithus abisectus ( T Sphenolithus distentus (25.98) T Sphenolithus pseudoradians (29.10) B Sphenolithus distentus (30.32) T Ericsonia formosa (32.9) T Hantkenina spp. (33.7) T Turborotalia cerroazulensis (33.8) T Discoaster saipanensis (34.0) T Discoaster barbadiensis (34.2) B Isthmolithus recurvus (36.6) B Chiasmolithus oamaruensis (37.0) T Chiasmolithus grandis (37.1) B Globigerinatheka semiinvoluta (38.4) B Dictyococcites bisectus (38.5) B Globoquadrina dehiscens (21.44) T Paragloborotalia opima (26.64) TC Chiloguembelina cubensis (27.92) B Sphenolithus ciperoensis (27.55) B "Globigerina" angulisuturalis (28.89) T Turborotalia ampliapertura (30.12) T Pseudohastigerina (32.0) (21.03) T Paragloborotalia kugleri T Subbotina angiporoides (29.67) B Paragloborotalia opima (30.54) T Reticulofenestra umbilicus ≥14 µm (31.7) T Increase Ericsonia obruta (32.2) T Isthmolithus recurvus (32.7) B Cassigerinella chipolensis (33.6) T Globigerinatheka index (34.3) T Calcidiscus protoannulus (35.4) T Globigerinatheka semiinvoluta (35.3) T Subbotina linaperta (37.7) T Morozovella spinulosa (38.1) T Acarinina coalingensis (39.0) T Paragloborotalia pseudokugleri (21.22) T "Globigerina" angulisuturalis (21.90) T Paragloborotalia kugleri (22.87) B Globigerinoides trilobus (22.87) T Globigerina euaptertura (23.03) T Tenuitella gemma (23.54) BC Globigerinoides primordius (23.54) T Paragloborotalia pseudokugleri (25.15) TC = Top common NN1 T = Top NN2 NP25 NP21 NP20 NP19 NP18 NP17 NP24 NP23 NP22 CN1c CP18 CP15 CP17 B = Base CP16c CP14b CP19b CP19a CP16b CP16a CN1a+b 12 M2 M1 P22 P20 P19 P18 P16 P15 P14 P21b P21a

Foraminifers Nannofossils Datum events

atna Priabonian Bartonian Rupelian Aquitanian Chattian

Age OTES

middle early late late N early ARTY

P Eocene Oligocene Miocene Epoch 33.7 23.03 Switch to CK95 - break in timescale XPLANATORY 3 2 2 2 1 2 2 1 1 1 2 1 3 1 2 1 2 1 1 2 2 1 2 CIENTIFIC 1 3 S Chron C7r C8r C9r C7Ar C15n C9n 2, E C7An C13r C15r C16r C10r C12r C11r C7n C17r C13n C12n C8n C6Br C6Cr C6AAn C16n C17n C11n C10n C18n C6AAr C6Bn C6Ar C6An C6Cn Figure 6, page 3.

20 21 22 23 32 24 25 26 27 28 29 30 31 33 34 35 36 37 38 39 40 HAPTER (Ma) Age HIPBOARD S C Figure F4 (continued). F4 Figure

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0 Inclination (°) Inclination Top 24 m cores of not 1218B, including Hole

A. -90

Chron Gilbert Brunhes Matuyama Gauss Polarity 13 180 ARTY P 1218 ITE Declination (°) Declination CIENTIFIC S Composite magnetic stratigraphy Composite at magnetic stratigraphy Site Virtual 1218. geomagnetic pole (VGP) werelatitudes 11,S Figure 7. (page 1 of 3 pages) An example of geomagnetic data and interpretation. Composite magnetic An Figure 7. (page 1 of 3 pages) AF geomagnetic pole (VGP) latitudes were obtained after partial 1218. Virtual Site stratigraphy at ODP Polarity column shows interpreted demagnetization of continuous measurements at a peak field of 20 mT. zones with an zones of normal (black) and reversed (white) magnetization, and gray intervals indicate Tensor 24 m of Hole 1218B, including cores not oriented with the Top A. uncertain polarity interpretation. section. tool. Note that both declination and inclination data are provided. B. Early Miocene-Pliocene shows the latitude of the magnetic pole based Geomagnetic Pole). VGP (Virtual Note the use of VGP inclination, on a single location rather than an average of locations; it is calculated from the declination, Leg 199 Initial Reports and the drillsite location. C. Early Oligocene-early Miocene section. From ODP ) (http://www-odp.tamu.edu/publications/199_IR/chap_11/chap_11.htm volume, Site 1218 chapter, 0 8 0 4

24 20 16 12 HAPTER (mcd) Depth HIPBOARD A C S Figure F12. Figure obtained after partial AF demagnetization of continuous measurements at a peak field of 20 mT. Polarity interpreted shows column of zones and andreversed (black) gray intervals magnetization, normal (white) indicate zones with an uncertain polarity interpretation. oriented with the Tensor (Continuedtool. pages.) ontwo next

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54 Subchron Chron/

C5n C5An.1n C5An.2n C5AAn C5ABn C5ACn C5ADn C5Bn C5Cn C5Dn C5En C6n Polarity VGP latitude (°) VGP latitude -90 -60 -30 0 30 60 90 35 40 45 50 55 60

14 Subchron Chron/

C2Ar C3n.2n C3An.1n C3An.2n C4n C3Bn C4An C5n C3n.1n C3n.3n C3n.4n Polarity Early section. Miocene–Pliocene ARTY B.

P Hole 1218A Hole 1218B 1218 ITE VGP latitude (°) VGP latitude CIENTIFIC S 11, S Figure 7 (page 2). -90 -60 -30 0 30 60 90

35 30 25 20 15 10 HAPTER (mcd) Depth HIPBOARD C S Figure F12 (continued). F12 Figure B

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Subchron Chron/

C10n.2n C11n.1n C11n.2n C12n C9n C10n.1n Polarity VGP latitude (°) VGP latitude -100 -50 0 50 100 140 150 160 170 180 190 200 210

Subchron Chron/

C6An.2n C6AAn C6AAr.1n C6AAr.2n C6Bn.1n C6Bn.2n C6Cn.1n C6Cn.2n C6Cn.3n C7n.1n C7n.2n C7An C8n.1n C8n.2n C9n C6n C6An.1n Polarity Early Oligocene–early Miocene section. ARTY C.

P 1218 ITE Hole 1218A Hole 1218B Hole 1218C VGP latitude (°) VGP latitude CIENTIFIC S 11, S Figure 7 (page 3). -100 -50 0 50 100 90 80 70 60

140 130 120 110 100 HAPTER (mcd) Depth HIPBOARD C S C Figure F12 (continued). F12 Figure

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 61 50 11.1 m/m.y. 4.84 m/m.y. 40 Slump? 10.32 m/m.y. volume, Site 1218 chapter. (http:// volume, Site 1218 chapter. 18.11 m/m.y. 30 8.64 m/m.y. 5.92 m/m.y. 16 Age (Ma) 20 2.63 m/m.y. 2.69 m/m.y. 1.1 m/m.y. ARTY 4.44 m/m.y. P 10 1218 ITE Radiolarians Nannofossils Foraminifers reversal Paleomagnetic CIENTIFIC S LSRs and chronostratigraphic markers. and LSRs 11, S Figure 8. Age-depth plot of Site 1218 using paleomagnetic chron boundaries and biostratigraphic Age-depth Figure 8. for the datums. LSRs (linear sedimentation rates) and chronostratigraphic markers. Data tables depths and ages of the paleomagnetic chrons and biostratigraphic datums are also available Leg 199 Initial Reports online at the following URL. From ODP ) www-odp.tamu.edu/publications/199_IR/chap_11/chap_11.htm 0 0

100 150 200 250 300 Depth (mcd) Depth HAPTER HIPBOARD S C Figure F18. Figure

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 53 C2Ar C3r C4n C4r C4An C4Ar C5n C5r C5An C5Ar C3n C3An Polarity volume, Site 1208 chapter. volume, Site 1208 chapter. Inclination (°) Inclination ) -80 -40 0 40 80 50 150 100 17 C2n C2An C1n C1r C2r K M J CM Polarity ARTY P Inclination (°) Inclination 1208 ITE CIENTIFIC S Inclination after AF demagnetization at peak fields of 20 mT as measured with the shipboard with of 20 as mT measured fields at peak AF demagnetization after Inclination 4, S (http://www-odp.tamu.edu/publications/198_IR/chap_04/chap_04.htm Figure 9. A second example of geomagnetic data and interpretation. Inclination after AF demagnetization at peak AF demagnetization second example of geomagnetic data and interpretation. Inclination after A Figure 9. The column at the right with the shipboard pass-through magnetometer at Hole 1208A. as measured fields of 20 mT Gray intervals indicate zones in of each plot shows interpreted zones of normal (black) and reversed (white) polarity. certain polarity zones farther which no polarity interpretation is possible. Polarity zones at the top of the section and Leg 198 Initial Reports downsection are tentatively correlated to polarity chrons. From ODP -80 -40 0 40 80 0 50

150 100 HAPTER (mbsf) Depth HIPBOARD C S Figure Figure F19. pass-through magnetometer at Hole 1208A. The column at the right of each plot shows interpreted zones of normal (black) and reversed (white) polarity. Gray intervals downsectionindicate zones farther zones in which polarity no certain polarity and inter- section the of top the at zones Polarity possible. is pretation are tentatively correlated to polarity chrons.

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 54 F19, 10 m/m.y. 8 10 12 volume, Site 1208 chapter. (http://www- volume, Site 1208 chapter. C4n C4An C5n C5An ) 6 18 Age (Ma) 24 m/m.y. C3n C3An Geomagnetic polarityGeomagnetic timescale 4 ARTY C2An P 2 40 m/m.y. 1208 ITE CIENTIFIC S Age-depth curve for Site 1208 derived from the magnetic stratigraphy shown in Figure C1n C2n 4, S Figure 10. Age-depth curve for Site 1208 derived from the magnetic stratigraphy shown in Figure 9 using Age-depth Figure 10. sedimentation rates in meters per Average the geomagnetic polarity timescale of Cande and Kent (1995). Leg 198 Initial Reports million years are also plotted. From ODP odp.tamu.edu/publications/198_IR/chap_04/chap_04.htm 0 0

300 250 200 150 100 Depth (mbsf) Depth HAPTER HIPBOARD S C p. 53, using the geomagnetic polarity timescale of Cande and Kent (1995). Average sedimentation rates in rates p.sedimentation Average (1995). Kent and Cande of timescale polarity geomagnetic the using 53, are plotted. also years million meters per Figure Figure F20.

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org provided (Table 1), interpret the polarity chrons interpret the polarity 1), (Table provided 1237C, and (Holes 1237B, Site 1237 for ODP in 4 sequence is shown The cored 1237D). meters 13 (upper 100 figures: Figure separate Figure 14 (100-200 depth, mcd); composite (200-300 mcd); and Figure 16 mcd); Figure 15 Construct your paleomagnetic (300-360 mcd). right of the data presented in stratigraphy to the in segments representing Figures 13-16. Color and leave segments of reverse normal polarity, polarity blank (white). (you can plot paleomagnetic interpretations as your biostratigraphic it on the same graph Use datums from the biostrat exercise). do the the graph paper provided. How well with calcareous nannofossil datums compare the polarity chron boundaries? 1. Using the Site 1237 biostratigraphic data biostratigraphic Site 1237 the 1. Using depth profile based on your 2. Plot an age versus 19 - - tion. Since this site is in the Southern Hemisphere, is in the Southern Hemisphere, tion. Since this site be represented by negative normal polarity will upwards, out of the Earth). inclination (positive magnetic data are either Second, well-preserved and there have reversed polarity, normal polarity or during the past 30 million been many reversals by the sequence cored at Site years represented independent means of will need some You 1237. black and white age control in order to interpret the respec- stripes of normal and reversed polarity, Biostratigraphy based on the established tively. of microfos sequence of first and last occurrences age control. sil species provides that first-order Paleomagnetic Stratigraphy Exercise Stratigraphy Paleomagnetic polarity the will interpret you exercise, In this for stratigraphy) reversal chrons (geomagnetic Pacific, located the southeast Site 1237 in ODP of Peru (16°0.421’S, margin on the continental the 12). First, notice and 11 Figures 76°22.685’W; Northern Hemisphere, this site. In the latitude of represented by positive inclina normal polarity is

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 29 Site locations and oceanographic fea- 70° B.

h CC nc 72° re T 20 Peru ru Peru e P 18 74° PCCC Pisco Pisco

PCC 76° ) 1237 20 78°

Site 1237 Nazca Fracture Zone Fracture Nazca 80° ARTY Site 1236

P Nazca Ridge Nazca (http://www-odp.tamu.edu/ volume, Site 1237 chapter. 82° 1237 1236 ITE CIENTIFIC Locations of Sites 1236 and 1237 and bathymetry. 20 S A. 84°W

>7000 <1000 1000-2000 2000-3000 3000-4000 4000-5000 5000-7000 8, S 22 Water depth (m) Water Figure 11. A. Locations of Sites 1236 and 1237 and bathymetry. B. Site locations B. Site 1236 and 1237 and bathymetry. A. Locations of Sites Figure 11. Peru and northern Chile (CC = Coastal Current, and oceanographic features off PCCC = Peru-Chile Countercurrent, PCC = Peru-Chile Current), after Strub et (contours al. (1998). Modern mean annual sea-surface temperatures (SSTs) 1999. From ODP are in degrees Celsius, after Ocean Climate Laboratory, Leg 202 Initial Reports publications/202_IR/chap_08/chap_08.htm S S HAPTER HIPBOARD 14° 16° 18° 20° 22° 24° 14° 16° 18° 20° 22° 24° A tures off Peru and northern Chile (CC = Coastal Current, PCCC = Peru-Chile Countercurrent, PCC = Peru- = PCC Countercurrent, Peru-Chile = PCCC Current, Coastal = (CC Chile northern and Peru off tures are (contours (SSTs) temperaturessea-surface annual meanModern (1998). al. et Strub after Current), Chile Celsius, degrees after in Ocean Climate Laboratory, 1999. S C Figure F1. Figure B

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 32 60° - volume, ) 70°

20 14 PCC Site 1237 80° 5 Ma Site 1236

5 Ma

18 16

90°

2 2

14 ARTY

38 Ma 24 P 25 Ma 100° SEC

24 1237 C) (° temperature sea-surface mean Annual ITE 25 Ma CIENTIFIC S

32 Ma

22 Tectonic backtrack of Site 1237, relative to a fixed South America. Poles of rotation are from Dun- 20

8, S

18 16 Figure 12. Tectonic backtrack of Site 1237, relative to a fixed South America. Poles of rotation are backtrack of Site 1237, relative to a fixed South Tectonic Figure 12. The dotted path represents positions from Duncan and Hargraves (1984) and Pisias et al. (1995). or direc in million-year increments. Numbers note ages (in millions of years) of changes in rate PCC = tion of drift. Contours of modern mean annual sea-surface temperature are superimposed. Leg 202 Initial Reports Peru-Chile Current, SEC = South Equatorial Current). From ODP (http://www-odp.tamu.edu/publications/202_IR/chap_08/chap_08.htm Site 1237 chapter. 110°W S 0° HAPTER HIPBOARD 40° 10° 30° 20° S C FigureF4. can and Hargraves inThe and Pisias represents al. dotted million-year positions path (1984) et (1995). in- mod- of Contours drift. of direction or rate in changes of years) of millions (in ages note Numbers crements. meanannualernsea-surface temperaturesuperimposed. arePeru-ChileSouth Equa-Current, PCC =SEC= Current).torial

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C3Ar/C3Bn/ C3Br C4n C4Ar/C4An/ C4Ar C5n C5r C5An C1n C1r C2r C2An C2Ar C3n C3r C3An C5Ar C5AAn/C5AAr/ C5ABn/C5ABr/ C5ACn C4ACn/C5ACr/ C5ADn C2

Cochiti Sifurfall Kaena Oldavai -

Jaramillo Reunion Nunivak Thvera Mammoth

interpretation Polarity zone

t Gilber Gauss Brunhes Matuyama 1r 2r 1r 3r Polarity Interpretation 2n 2n 3n 1n 2Ar 2r.1n 1r.1n 3n.1n 3n.2n 3n.3n 3n.3n 2An.1n °) Hole 1237D Inclination ( -90 -30 30 90 C 22 °) ) ) Hole) 1237D with accompanying the interpretations. polarity volume, Site 1237 chapter. (http://www-odp.tamu.edu/ volume, Site 1237 chapter. C Hole 1237C Inclination ( -90 -30 30 90 ARTY P °) ) Hole 1237C, and ( and 1237C, Hole ) 1237 B ITE CIENTIFIC S Hole 1237B Inclination ( 8, S Figure 13. Inclination after demagnetization at peak alternating fields of 25 mT for the upper 100 mcd Figure 13. Inclination after demagnetization at peak alternating fields of 25 mT interpreta of (A) Hole 1237B, (B) Hole 1237C, and (C) Hole 1237D with the accompanying polarity tions. From ODP Leg 202 Initial Reports tions. From ODP publications/202_IR/chap_08/chap_08.htm -90 -30 30 90 0 20 40 60 80 100

) Hole 1237B, ( 1237B, Hole ) HAPTER (mcd) Depth HIPBOARD A S C FigureF29. Inclination after demagnetization at peak alternating( fields of 25 mT for the upper 100 mcd of AB

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C3Ar/C3Bn/ C3Br C4n C4Ar/C4An/ C4Ar C5n C5r C5An C1n C1r C2r C2An C2Ar C3n C3r C3An C5Ar C5AAn/C5AAr/ C5ABn/C5ABr/ C5ACn C4ACn/C5ACr/ C5ADn C2 3Bn/3Br/4n interpretatio Polarity zone 5r Polarity Interpretation 4r 3r 5n 4Ar 3Ar 4An 3n.3n 5An.1n 5An.2n 3An.2n? 3An.1n ? °) volume, Site 1237 chapter. volume, Site 1237 chapter. ) MCD stack Inclination ( ) the stacked and smoothed record with the accompa- -90 -30 30 90 C °) 23 Hole 1237C Inclination ( ) Hole 1237C, and ( -90 -30 30 90 B ARTY P °) 1237 ITE CIENTIFIC ) ) Hole 1237B, ( A S Inclination after demagnetization at peak alternating fields of after mTatpeak 25 fields Inclination demagnetization thealternating to 100- for 200-mcd Hole 1237B Inclination ( 8, S Figure 14. Inclination after demagnetization at peak alternating fields of 25 mT for the 100- to 200- Figure 14. Inclination after demagnetization at peak alternating fields of 25 mT with the mcd interval of (A) Hole 1237B, (B) Hole 1237C, and (C) the stacked and smoothed record Leg 202 Initial Reports accompanying polarity interpretations. From ODP (http://www-odp.tamu.edu/publications/202_IR/chap_08/chap_08.htm -90 -60 -30 0 30 60 90

100 120 140 160 180 200 HAPTER (mcd) Depth HIPBOARD A BC S C Figure F30. interval of ( nying polarity interpretations.

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org SHIPBOARD SCIENTIFIC PARTY CHAPTER 8, SITE 1237 64 ) ) Hole B ) Hole 1237B, ( A

C5AAn/C5AAr/ C5ABn/C5ABr/ C5ACn C4ACn/C5ACr/ C5ADn C1n C1r C2n C2r C2An C2Ar C3n C3r C3An C3Ar/C3Bn/ C3Br C4n C4Ar/C4An/ C4Ar C5n C5r C5An C5Ar

to 5ADn to )

Polarity zone Polarity

interpretation n 5C AAn Not interpreted Not n n Polarity Interpretation 6n 5Ar 5Dr 6Bn 6Br 6C 5Br 5Cr 5En 5D Stack Inclination (°) -90 -60 -30 0 30 60 90 D Hole 1237D Hole Inclination (°) 24 -90 -60 -30 0 30 60 90 C Hole 1237C Hole Inclination (°) ) the stacked and smoothed record with the accompanying polarity interpretations. D -90 -60 -30 0 30 60 90 volume, Site 1237 chapter. (http://www-odp.tamu.edu/publications/202_IR/chap_08/chap_08.htm volume, Site 1237 chapter. B Inclination after demagnetization at peak alternating fields of 25 mT for the 200- to 300-mcd interval of ( Hole 1237B Hole Inclination (°) ) Hole) 1237D, and ( C Figure 15. Inclination after demagnetization at peak alternating fields of 25 mT for the 200- to 300-mcd interval of (A) Hole 1237B, Figure 15. Inclination after demagnetization at peak alternating fields of 25 mT polarity interpretations. From (B) Hole 1237C, (C) Hole 1237D, and (D) the stacked and smoothed record with the accompanying Initial Reports Leg 202 ODP -90 -60 -30 0 30 60 90

300 280 260 240 220 200 Depth (mcd) Depth A 1237C, ( Figure F31.

How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org 65 n C3Ar/C3Bn/ C3Br C4n C4Ar/C4An/ C4Ar C5n C5r C5An C1n C1r C2r C2An C2Ar C3n C3r C3An C5Ar C5AAn/C5AAr/ C5ABn/C5ABr/ C5ACn C4ACn/C5ACr/ C5ADn C2

interpretation Polarity zone Not interpreted Not 9N 8N 7N 6Cr Polarity Interpretation 6Cn.3n °) volume, Site 1237 chapter. volume, Site 1237 chapter. ) MCD Stack Inclination ( -90 -30 30 90 ) the stacked and smoothed record with the accompa- C 25 °) Hole 1237C Inclination ( ) Hole 1237C, and ( -90 -30 30 90 B BC ARTY P °) 1237 ITE CIENTIFIC ) ) Hole 1237B, ( A Hole 1237B S Inclination ( 8, S Figure 16. Inclination after demagnetization at peak alternating fields of 25 mT for the 300- to 360- Figure 16. Inclination after demagnetization at peak alternating fields of 25 mT with the mcd interval of (A) Hole 1237B, (B) Hole 1237C, and (C) the stacked and smoothed record Leg 202 Initial Reports accompanying polarity interpretations. From ODP (http://www-odp.tamu.edu/publications/202_IR/chap_08/chap_08.htm -90 -60 -30 0 30 60 90

360 350 340 330 320 310 300 HAPTER (mcd) Depth HIPBOARD S C Figure F32.of after mTatpeak 25 fields Inclination demagnetization thealternating to 300- for 360-mcd interval of ( nying polarity interpretations. A

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.4 .4 4-C 6194 5-C 3.676 .0140 4.84.63 146.18 134.03 0.00 7.64 138.66 1 15H-CC, 129.40 26 14H-CC, 7.64 7.64 D reinholdii Nitzschia FO

85 .0 .0 3-C 1.51H3 4128 .000 2.1127 1.56 132.71 121.31 0.00 7.30 122.86 34 14H-3, 119.75 1 13H-CC, 7.30 7.30 D s.l. miocenica Nitzschia FO

N72 .41H3 5127 5-,7 3.972 .0142 4.31.51 146.83 134.28 0.00 7.24 135.79 75 15H-5, 132.77 75 15H-3, 7.24 7.24 CN primus Amaurolithus FO

F71 .21HC,1197 4-C 6194 .200 2.8159 4.83 135.98 124.58 0.00 7.12 129.40 26 14H-CC, 119.75 1 13H-CC, 7.12 7.12 PF conomiozea Globorotalia FO

> mC .068 4-C 6194 5-,7 2.568 .0195 4.30.17 141.73 129.58 0.00 6.80 129.75 75 15H-1, 129.40 26 14H-CC, 6.80 6.80 CN µm >7 pseudoumbilicus Reticulofenestra interval Absence LO

Thalassiosira convexa v. aspinosa v. convexa Thalassiosira FO .7 .7 3-C 1.51H3 4128 .700 2.1127 1.56 132.71 121.31 0.00 6.57 122.86 34 14H-3, 119.75 1 13H-CC, 6.57 6.57 D

Pulletianita primalis Pulletianita FO F64 .01HC,1 0.11HC,1197 .000 1.8156 4.97 125.69 114.78 0.00 6.40 119.75 1 13H-CC, 109.81 18 12H-CC, 6.40 6.40 PF

Globigerinoides conglobarus Globigerinoides FO F62 .01HC,1 0.11HC,1197 .000 1.8156 4.97 125.69 114.78 0.00 6.20 119.75 1 13H-CC, 109.81 18 12H-CC, 6.20 6.20 PF

Globorotalia margaritae Globorotalia FO F60 .91HC,2 0.01HC,1 0.160 .0154 1.84.36 115.68 105.46 0.00 6.09 109.81 18 12H-CC, 101.10 25 11H-CC, 6.09 6.09 PF

.8 .8 2-,3 0.01HC,1197 .800 1.8134 7.18 123.49 112.58 0.00 6.08 119.75 1 13H-CC, 105.40 38 12H-4, 6.08 6.08 D s.s. miocenica Nitzschia LO

Globorotalia tumida Globorotalia FO F58 .21HC,1 12 1-C 5111 .200 62 0.44.90 105.64 96.20 0.00 5.82 101.10 25 11H-CC, 91.29 10 10H-CC, 5.82 5.82 PF

Thalassiosira oestrupii Thalassiosira FO .4 .4 1-C 5111 2-,2 0.256 .0109 1.3–0.19 111.13 100.91 0.00 5.64 100.72 22 12H-1, 101.10 25 11H-CC, 5.64 5.64 D

Discoaster quinqueramus Discoaster LO N55 .61H4 59.81H5 59.955 .09.4167 0.75 106.71 97.04 0.00 5.56 97.79 75 11H-5, 96.28 75 11H-4, 5.56 5.56 CN

Nitzschia jouseae Nitzschia FO .2 .2 HC,2 18 0-C 09.951 .08.89.74.72 94.87 86.58 0.00 5.12 91.29 10 10H-CC, 81.86 20 9H-CC, 5.12 5.12 D

Nitzschia cylindrica Nitzschia LO .8 .8 HC,3 26 H6 07.348 .07.58.93.59 82.79 76.25 0.00 4.88 79.83 30 9H-6, 72.66 39 8H-CC, 4.88 4.88 D

Sphaeroidinellopsis kochi Sphaeroidinellopsis LO F45 .38-C 97.69-C 08.645 .07.68.14.60 83.81 77.26 0.00 4.53 81.86 20 9H-CC, 72.66 39 8H-CC, 4.53 4.53 PF

Globoturborotalia nepenthes Globoturborotalia LO F42 .08-C 97.69-C 08.642 .07.68.14.60 83.81 77.26 0.00 4.20 81.86 20 9H-CC, 72.66 39 8H-CC, 4.20 4.20 PF

Pseudoemiliania lacunosa Pseudoemiliania FO N40 .09-,7 57 H4 57.740 .07.38.10.75 83.91 76.53 0.00 4.00 77.27 75 9H-4, 75.78 78 9H-3, 4.00 4.00 CN .

Reticulofenestra pseudoumbilicus Reticulofenestra LO N38 .08-,7 32 H2 86.938 .06.26.40.77 69.74 64.02 0.00 3.80 64.79 78 8H-2, 63.25 75 8H-1, 3.80 3.80 CN

Globorotalia plesiotumida Globorotalia LO F37 .77-C 96.08-C 97.637 .06.37.84.93 73.38 67.73 0.00 3.77 72.66 39 8H-CC, 62.80 19 7H-CC, 3.77 3.77 PF

Sphaeroidinella dehiscens Sphaeroidinella FO F32 .56-C 05.17-C 96.032 .05.66.04.65 63.80 58.16 0.00 3.25 62.80 19 7H-CC, 53.51 30 6H-CC, 3.25 3.25 PF

.7 .7 H1 1 41 H3 35.431 .05.26.91.32 60.99 55.42 0.00 3.17 56.74 73 7H-3, 54.10 110 7H-1, 3.17 3.17 D s.l. praebergonii Rhizosolenia FO

Sphaeroidinellopsis seminula Sphaeroidinellopsis LO F31 .26-C 05.17-C 96.031 .05.66.04.65 63.80 58.16 0.00 3.12 62.80 19 7H-CC, 53.51 30 6H-CC, 3.12 3.12 PF

Dentoglobigerina altispira Dentoglobigerina LO F30 .95-C 24.26-C 05.130 .04.75.64.75 53.26 48.77 0.00 3.09 53.51 30 6H-CC, 44.02 22 5H-CC, 3.09 3.09 PF

Nitzschia jouseae Nitzschia LO .7 .7 H1 54.56-,2 52 .700 47 04 0.49 50.46 44.74 0.00 2.77 45.23 22 6H-2, 44.25 75 6H-1, 2.77 2.77 D

Discoaster tamalis Discoaster LO N27 .66-,7 42 H2 54.627 .04.15.30.75 50.73 45.01 0.00 2.76 45.76 75 6H-2, 44.25 75 6H-1, 2.76 2.76 CN

Discoaster surculus Discoaster LO N26 .15-,7 23 HC,2 40 .100 31 64 0.86 46.43 43.16 0.00 2.61 44.02 22 5H-CC, 42.30 75 5H-6, 2.61 2.61 CN

Discoaster pentaradiatus Discoaster LO N24 .45-,7 23 HC,2 40 .400 31 64 0.86 46.43 43.16 0.00 2.44 44.02 22 5H-CC, 42.30 75 5H-6, 2.44 2.44 CN

.1 .1 H6 03.64-C 03.524 .03.13.11.04 37.81 33.51 0.00 2.41 34.55 20 4H-CC, 32.46 40 4H-6, 2.41 2.41 D s.l. convexa Thalassiosira LO

Globorotalia puncticulata Globorotalia LO F24 .13-C 92.04-C 03.524 .02.83.84.78 32.48 29.78 0.00 2.41 34.55 20 4H-CC, 25.00 19 3H-CC, 2.41 2.41 PF

volume, Site 1237 site chapter (choose pdf version rather than online html

Fragilariopsis doliolus Fragilariopsis FO .0 .0 H3 02.24-,4 24 .000 01 44 2.27 34.49 30.19 0.00 2.00 32.46 40 4H-6, 27.92 40 4H-3, 2.00 2.00 D

Discoaster brouweri Discoaster LO N19 .64-C 03.55-,7 47 .600 46 84 0.10 38.44 34.65 0.00 1.96 34.75 75 5H-1, 34.55 20 4H-CC, 1.96 1.96 CN

F17 .72-C 41.73-C 92.017 .02.42.64.77 20.36 20.24 0.00 1.77 25.00 19 3H-CC, 15.47 24 2H-CC, 1.77 1.77 PF extremus Globigerinoides LO

Calcidiscus macintyrei Calcidiscus LO N15 .94-,7 82 H6 53.115 .03.43.42.27 34.84 30.54 0.00 1.59 32.81 75 4H-6, 28.27 75 4H-3, 1.59 1.59 CN

(large) Gephyrocapsa FO N14 .54-,7 67 H3 52.714 .02.23.20.75 31.82 27.52 0.00 1.45 28.27 75 4H-3, 26.76 75 4H-2, 1.45 1.45 CN

(large) Gephyrocapsa LO N12 .44-,7 52 H2 52.612 .02.13.10.76 30.31 26.01 0.00 1.24 26.76 75 4H-2, 25.25 75 4H-1, 1.24 1.24 CN

Rhizosolenia matuyamai Rhizosolenia FO .8 .8 HC,1 50 H1 02.011 .02.52.5–0.05 27.65 24.95 0.00 1.18 24.90 40 4H-1, 25.00 19 3H-CC, 1.18 1.18 D

Reticulofenestra asanoi Reticulofenestra FO N10 .83-C 92.04-,7 52 .800 51 78 0.13 27.83 25.13 0.00 1.08 25.25 75 4H-1, 25.00 19 3H-CC, 1.08 1.08 CN

Rhizosolenia matuyamai Rhizosolenia LO .5 .5 H3 51.73-,7 17 .500 02 13 1.51 21.38 20.28 0.00 1.05 21.79 75 3H-5, 18.77 75 3H-3, 1.05 1.05 D

Reticulofenestra asanoi Reticulofenestra LO N08 .83-,6 01 H5 02.408 .02.92.90.75 21.99 20.89 0.00 0.88 21.64 60 3H-5, 20.13 60 3H-4, 0.88 0.88 CN

Nitzschia fossilis Nitzschia LO .0 .0 HC,2 54 HC,1 50 .000 02 03 4.77 20.36 20.24 0.00 0.70 25.00 19 3H-CC, 15.47 24 2H-CC, 0.70 0.70 D

ARTY Globorotalia tosaensis Globorotalia LO F06 .51-C .12-C 41.706 .01.91.74.98 10.07 10.49 0.00 0.65 15.47 24 2H-CC, 5.51 9 1H-CC, 0.65 0.65 PF

Nitzschia reinholdii Nitzschia LO P 3.16 18.76 18.63 0.00 0.62 21.79 75 3H-5, 15.47 24 2H-CC, 0.62 0.62 D

Pseudoemiliania lacunosa Pseudoemiliania LO N04 .62-,7 22 H7 01.404 .01.11.61.33 12.76 13.61 0.00 0.46 14.94 40 2H-7, 12.28 75 2H-5, 0.46 0.46 CN

Globorotalia hirsuta Globorotalia FO F04 .51-C .12-C 41.704 .01.91.74.98 10.07 10.49 0.00 0.45 15.47 24 2H-CC, 5.51 9 1H-CC, 0.45 0.45 PF

http://www-odp.tamu.edu/publications/202_IR/chap_08/chap_08.htm

Emiliania huxleyi Emiliania FO 1237 0.13 5.39 5.39 0.00 0.26 5.51 9 1H-CC, 5.26 75 1H-4, 0.26 0.26 CN

202-1237B- 202-1237B-

ITE CIENTIFIC

Minimum Maximum Maximum Minimum (±m) (mcd) (mbsf) (±) Average (mbsf) (cm) interval (mbsf) (cm) interval Datum

S Source

version), Table 1. (two pages) Age-Depth control points for ODP Hole 1237B. These are the biostratigraphic datums (microfossil These Hole 1237B. points for ODP Age-Depth control 1. (two pages) Table This image is of Site 1237. first and last occurrence datums; FOs and LOs) used to calibrate the paleomagnetic record 202 Initial Reports Leg scanned from the ODP

Uncertainty Uncertainty Average Average Uncertainty Depth section, Core, Depth section, Core,

8, 8, S (Ma) Age

(FO presence/LO absence) presence/LO (FO (LO presence/FO absence) Age (Ma) Age absence) presence/FO (LO Depth

Top sample Top Bottom sample Bottom

Table T10. Table See table notes. table See Age-depth control points, Hole 1237B. ( 1237B. Hole points, control Age-depth HAPTER page). next on Continued HIPBOARD S C

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Notes: FO = first occurrence, LO = last occurrence. CN = calcareous nannofossils, PF = planktonic foraminifers, D = diatoms. = D foraminifers, planktonic = PF nannofossils, calcareous = CN occurrence. last = LO occurrence, first = FO Notes:

F3.03.03HC,2 0.43H6 5382 03 .0344 5.63.88 355.16 304.42 0.00 30.30 308.29 75 33H-6, 300.54 25 32H-CC, 30.30 30.30 PF ampliapertura Turborotalia LO

F3.03.03HC,2 0.43H6 5382 00 .0344 5.83.88 355.28 304.42 0.00 30.00 308.29 75 33H-6, 300.54 25 32H-CC, 30.00 30.00 PF angiporoides Subbotina LO

Sphenolithus ciperoensis Sphenolithus FO N2. 993H5 5367 3-,7 0.92.000 0.4374 0.75 347.40 307.54 0.00 29.90 308.29 75 33H-6, 306.78 75 33H-5, 29.9 29.9 CN

Globoturborotalia angulisuturalis Globoturborotalia FO F2.02.03HC,1 9.73HC,2 0.42.000 9.1324 4.74 332.42 295.81 0.00 29.40 300.54 25 32H-CC, 291.07 16 31H-CC, 29.40 29.40 PF

Sphenolithus pseudoradians Sphenolithus LO N2. 913H5 5367 3-,7 0.92.000 0.4374 0.75 347.40 307.54 0.00 29.10 308.29 75 33H-6, 306.78 75 33H-5, 29.1 29.1 CN

Sphenolithus predistentus Sphenolithus LO N2. 753HC,1 9.73H1 5212 75 .0211 2.70.09 327.77 291.16 0.00 27.50 291.25 75 32H-1, 291.07 16 31H-CC, 27.5 27.5 CN

Sphenolithus distentus Sphenolithus LO N2. 753H7 0204 1-C 6210 75 .0207 2.80.30 326.18 290.77 0.00 27.50 291.07 16 31H-CC, 290.47 40 31H-7, 27.5 27.5 CN

Globigerinoides primordius Globigerinoides FO F2.02.03HC,0212 1-C 6210 67 .0261 2.74.91 320.67 286.16 0.00 26.70 291.07 16 31H-CC, 281.24 0 30H-CC, 26.70 26.70 PF

Sphenolithus ciperoensis Sphenolithus LO N2.52.52H5 5287 9-,7 6.82.500 6.8303 0.00 300.39 268.78 0.00 24.75 268.78 75 29H-5, 268.78 75 29H-5, 24.75 24.75 CN

Zygrhabdolithus bijugatus Zygrhabdolithus LO N2.02.02H5 5287 9-,7 6.82.000 6.8303 0.00 300.39 268.78 0.00 24.50 268.78 75 29H-5, 268.78 75 29H-5, 24.50 24.50 CN

F2.02.02HC,1 7.53HC,0212 43 .0266 0.14.65 309.21 276.60 0.00 24.30 281.24 0 30H-CC, 271.95 15 29H-CC, 24.30 24.30 PF common primordius Globigerinoides FO

Reticulofenestra bisecta Reticulofenestra LO N2.02.02H4 5272 9-,7 6.82.000 6.3296 0.75 299.64 268.03 0.00 23.90 268.78 75 29H-5, 267.27 75 29H-4, 23.90 23.90 CN

Globigerinoides trilobus Globigerinoides FO F2.02.02HC,1 6.82HC,1 7.52.000 6.2275 4.74 297.55 267.22 0.00 23.40 271.95 15 29H-CC, 262.48 16 28H-CC, 23.40 23.40 PF

Globoquadrina dehiscens Globoquadrina FO F2.02.02HC,1 5.02HC,1 6.82.000 5.4264 4.84 286.40 257.64 0.00 23.20 262.48 16 28H-CC, 252.80 14 27H-CC, 23.20 23.20 PF

Globoquadrina binaiensis Globoquadrina FO F2.02.02HC,1 5.02HC,1 6.82.000 5.4264 4.84 286.40 257.64 0.00 22.10 262.48 16 28H-CC, 252.80 14 27H-CC, 22.10 22.10 PF

Globoturborotalia angulisuturalis Globoturborotalia LO F2.02.02HC,1 3.82HC,9234 16 .0285 6.14.90 264.31 238.58 0.00 21.60 243.48 9 26H-CC, 233.68 10 25H-CC, 21.60 21.60 PF

Paragloborotalia kugleri Paragloborotalia LO F2.02.02HC,1 3.82HC,9234 15 .0285 6.14.90 264.31 238.58 0.00 21.50 243.48 9 26H-CC, 233.68 10 25H-CC, 21.50 21.50 PF

Sphenolithus belemnos Sphenolithus FO N1.01.02H6 5228 4-,4 2.61.000 2.9267 0.57 246.74 223.39 0.00 19.20 223.96 40 24H-7, 222.81 75 24H-6, 19.20 19.20 CN

Globoquadrina binaiensis Globoquadrina LO F1.01.02HC,1 2.72HC,1 3.81.000 2.3235 4.76 253.50 228.93 0.00 19.10 233.68 10 25H-CC, 224.17 10 24H-CC, 19.10 19.10 PF

Sphenolithus belemnos Sphenolithus LO N1.01.02HC,1 1.72H1 5252 85 .0249 3.10.29 237.71 214.96 0.00 18.50 215.25 75 24H-1, 214.67 16 23H-CC, 18.50 18.50 CN

Sphenolithus heteromorphus Sphenolithus FO N1.01.02HC,1 1.72H1 5252 82 .0249 3.10.29 237.71 214.96 0.00 18.20 215.25 75 24H-1, 214.67 16 23H-CC, 18.20 18.20 CN

Calcidiscus premacintyrei Calcidiscus FO N1.01.02H3 5287 3-,7 1.81.000 0.3216 0.75 231.68 209.53 0.00 17.40 210.28 75 23H-4, 208.77 75 23H-3, 17.40 17.40 CN

Catapsydrax dissimilis Catapsydrax LO F1.01.02HC,1 1.72HC,1 2.71.000 1.2221 4.75 242.17 219.42 0.00 17.30 224.17 10 24H-CC, 214.67 16 23H-CC, 17.30 17.30 PF

Globorotalia semivera Globorotalia LO F1.01.02HC,1 1.72HC,1 2.71.000 1.2221 4.75 242.17 219.42 0.00 17.30 224.17 10 24H-CC, 214.67 16 23H-CC, 17.30 17.30 PF

Globorotalia birnageae Globorotalia FO F1. 672HC,1 1.72HC,1 2.71.000 1.2221 4.75 242.17 219.42 0.00 16.70 224.17 10 24H-CC, 214.67 16 23H-CC, 16.7 16.7 PF

Globigerinoides diminitus Globigerinoides FO F1. 612HC,1254 3-C 6246 61 .0200 3.14.62 231.31 210.06 0.00 16.10 214.67 16 23H-CC, 205.44 1 22H-CC, 16.1 16.1 PF

Globorotalia miozea Globorotalia LO F1. 592HC,1 9.92HC,1254 59 .0206 2.94.83 220.39 200.62 0.00 15.90 205.44 1 22H-CC, 195.79 14 21H-CC, 15.9 15.9 PF

Globorotalia praemenardii Globorotalia FO F1. 492HC,1 9.92HC,1254 49 .0206 2.94.83 220.39 200.62 0.00 14.90 205.44 1 22H-CC, 195.79 14 21H-CC, 14.9 14.9 PF

Globorotalia peripheroacuta Globorotalia FO F1.01.02HC,1 9.92HC,1254 48 .0206 2.94.83 220.39 200.62 0.00 14.80 205.44 1 22H-CC, 195.79 14 21H-CC, 14.80 14.80 PF

Globorotalia peripheroronda Globorotalia LO F1. 462HC,2 8.12HC,1 9.91.000 9.0297 4.69 209.78 191.10 0.00 14.60 195.79 14 21H-CC, 186.41 24 20H-CC, 14.6 14.6 PF

Globorotalia archeomenardii Globorotalia LO F1. 421HC,1 7.12HC,2 8.11.000 8.1193 4.80 199.36 181.61 0.00 14.20 186.41 24 20H-CC, 176.81 13 19H-CC, 14.2 14.2 PF

Sphenolithus heteromorphus Sphenolithus LO N1.71.72H7 0159 0-C 4164 35 .0161 0.30.23 204.33 186.18 0.00 13.57 186.41 24 20H-CC, 185.95 40 20H-7, 13.57 13.57 CN

s.l. fohsi Globorotalia FO F1.21.21HC,1 7.12HC,2 8.11.200 8.1193 4.80 199.36 181.61 0.00 13.42 186.41 24 20H-CC, 176.81 13 19H-CC, 13.42 13.42 PF

Calcidiscus premacintyrei Calcidiscus LO N1. 241H6 5153 9-,4 7.61.000 7.8132 0.58 193.23 175.88 0.00 12.40 176.46 40 19H-7, 175.30 75 19H-6, 12.4 12.4 CN

s.l. fohsi Globorotalia LO F1.81.81HC,1168 9-C 3168 16 .0118 8.94.96 188.39 171.85 0.00 11.68 176.81 13 19H-CC, 166.89 1 18H-CC, 11.68 11.68 PF

Cyclicargolithus floridanus Cyclicargolithus LO N1. 31 9-,7 7.01H6 5153 24 .0145 9.00.75 191.90 174.55 0.80 12.40 175.30 75 19H-6, 173.80 75 19H-5, 13.19 11.6 CN

Coronocyclus nitescens Coronocyclus LO N1.31.31H3 5107 9-,7 7.91.300 7.4188 0.75 188.89 171.54 0.00 12.43 172.29 75 19H-4, 170.78 75 19H-3, 12.43 12.43 CN

ARTY Globoturborotalia nepenthes Globoturborotalia FO F1.91.91HC,1168 9-C 3168 11 .0118 8.94.96 188.39 171.85 0.00 11.19 176.81 13 19H-CC, 166.89 1 18H-CC, 11.19 11.19 PF

P Coccolithus miopelagicus Coccolithus LO N1.01.01H4 5124 8-,7 6.41.000 6.9189 0.75 178.92 163.19 0.00 10.40 163.94 75 18H-5, 162.43 75 18H-4, 10.40 10.40 CN

Neogloboquadrina acostaensis Neogloboquadrina FO F98 .21H1 8189 7-C 1180 .200 5.9182 4.51 168.29 153.49 0.00 9.82 158.00 21 17H-CC, 148.98 98 17H-1, 9.82 9.82 PF

Discoaster hamatus Discoaster LO N94 .01H5 5147 7-,7 5.894 .0155 7.30.75 170.33 155.53 0.00 9.40 156.28 75 17H-6, 154.78 75 17H-5, 9.40 9.40 CN

Reticulofenestra pseudoumbilicus Reticulofenestra interval absence FO 1237 0.06 163.61 148.81 0.00 8.85 148.86 86 17H-1, 148.75 75 17H-1, 8.85 8.85 CN >7µm

Globorotalia plesiotumida Globorotalia FO F85 .81HC,1186 6-C 2182 .800 4.4160 4.78 156.06 143.44 0.00 8.58 148.21 12 16H-CC, 138.66 1 15H-CC, 8.58 8.58 PF ITE CIENTIFIC

Table 1, page two. Table

Minimum Maximum Maximum Minimum (mbsf) Average Average (mbsf) (cm) interval (mbsf) (cm) interval (±m) (mcd) (mbsf) (±) Datum S Source

Core, section, section, Core, Depth Depth section, Core, Depth Uncertainty Uncertainty Uncertainty Uncertainty Average

8, 8, S Average Age (Ma) Age

(FO presence/LO absence) presence/LO (FO (LO presence/FO absence) Age (Ma) Age absence) presence/FO (LO Depth

Top sample Top Bottom sample Bottom HAPTER (continued). T10 Table HIPBOARD S C

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How Old Is It? Part 2 – Magnetostratigraphy Teaching for Science • Learning for LifeTM | www.oceanleadership.org