Many of the core concepts in earth science systems are complex and counterintuitive, but well illustrated through imagery and/or animation. We have developed a new tool, "ImageQuiz," that uses wireless technologies to present images and provide a question requiring a point response. In the study presented here, we use Peer Instruction techniques (Mazur, 1997) in a large geosciences class and deliver ImageQuizes via wireless PocketPC computers. We will discuss development, implementation and learning outcomes.

Sites dilled by Leg 199 form a latitudinal transect across the Paleogene equator, extending across paleolatitudes of 4.5°S to 18.5°N. Drillsites were explicitly located atop sea-floor anomaly 25, approximately 56 million years old, ensuring recovery of early Eocene carbonate sediment. Many of the earlier DSDP and ODP efforts with regard to Paleogene paleoceanography were confounded by the common Eocene cherts. The drilling strategy adopted by Leg 199 obviated some of these problems, with the result that we have increased amount of information regarding the Paleogene low-latitude CCD several fold. To reconstruct the CCD we have assumed that sea-floor subsidence follows the simple square root of age law, and that the depth of the Paleogene East Pacific Rise axis was 2750 meters, in agreement with earlier studies. Bulk density considerations suggest that sediment loading depresses the sea floor by an amount equal to half the sediment so any complete determination of age-depth histories requires an unloading step. Results of these determinations for the Leg 199 sites are such that paleodepths are comparable among the sites to ±50 meters, and the absolute values of the paleodepths depend on how good the ridge axis paleodepth assumption is. Results show a shallow early Eocene CCD of 3200 meters at the equator, deepening to 3600 meters at 10°N latitude. In the modern ocean the CCD always deepens towards the equator, so something quite different has occurred in the early Eocene. The CCD remained at these shallow levels until the end of the Eocene, with the exception of a sudden sharp excursion (drop/rise) of about 700 meters at 41 Ma. The large drop of the CCD at the end of the Eocene has been known since the earliest CCD studies, but completely recovered sections across this boundary have been few or none. Leg 199 recovered complete records of this event at all 8 drillsites. At the time of the Eocene/Oligocene boundary the CCD in the low-latitude Pacific fell by over 1000 meters to 4350m, the largest change in ocean paleochemistry in the entire Cenozoic. This drop occurred in two steps, each one occurring as rapidly as in thousands of years. A preliminary look at the oxygen isotopic record of these materials at Site 1218 shows the CCD drop is in phase with the long recognized O-18 shift at the E/O boundary. The Neogene CCD in sub-tropical North Pacific lies at about 4600 m, about 500 meters deeper than the CCD of the sub-tropical South Pacific.

Leg 199 drilled a series of sites in the equatorial Pacific in order to investigate the paleoceanography of the Paleogene Pacific Ocean. The two deepest cored sites, (1218 and 1219) have provided continuous/near continuous spliced sedimentary sections and in situ wireline log data. Comparison of core to log data sets shows the familiar non-linear, increasing with depth, miss-match between the core (metres composite depth - mcd) and log (mbsf) depths and concomitant offset between core and log physical property data sets e.g. porosity, density, velocity. The depth miss-matches represent core expansion due to elastic rebound experienced by the sediments upon unloading i.e. removal of overburden stress, which is a function of the sediment void ratio and log of the effective in situ stress. The increasing depth offset observed between the 1218 core and log data is used to calculate an expansion index (C$_{r}$) for continuous discrete measurement intervals, down the core. The C$_{r}$ values are used to re-compress the core (mcd) depth scale and as expected provide a good match with the log (mbsf) depths. The C$_{r}$ values are also used to correct the core index property data, to in situ values. The quality of the corrected core index property data is good when compared with the in situ measured log data. C$_{r}$ values are dependent upon the sediment composition (especially the quantity of clay) and core light absorption spectroscopy (LAS) data collected on Leg 199, provides a continuous down-core record of sediment composition, in terms of the percent clay, carbonate and opal. A relationship between the C$_{r}$ values and the sediment LAS composition is established and is then applied to the Site 1219 core LAS data, allowing appropriate C$_{r}$ values to be assigned to continuous, discrete core intervals. These composition based C$_{r}$ values are then used to re-calculate the core (mcd) depths and correct the index property data to in situ values. The quality of the depth and index property corrections are checked by comparison with the in situ measured log data, and provide encouraging results.

ODP Site 1218 was cored in the equatorial Pacific Ocean during Leg199. The 270 m of sediments from the site yielded an excellent record of the geomagnetic polarity reversals for the entire Miocene and most of the Oligocene. Nannofossils and radiolarians indicate that the section is biostratigraphically complete with no apparent hiatuses. The top 165 m of Site 1218 was cored using the Advanced Piston Corer and sediment cores could be azimuthally oriented preserving the declination information. The high-resolution magnetostratigraphic record has been obtained by measurements made on u-channel samples, augmented by about 300 discrete samples. U-channel samples were measured at 1cm interval and stepwise demagnetized in alternating field up to a maximum peak field of 80 mT. The Characteristic Remanent Magnetization directions were determined each 1 cm by principal component analysis for demagnetization steps in the 20 mT to 50mT peak field range. A similar treatment was carried out on the discrete samples, that gave results compatible with u-channel measurements. . Magnetostratigraphy from u-channel samples are compared with shipboard data that was based on blanket demagnetization at peak AF fields of 20 mT. U-channel measurements add more detail to the magnetostratigraphic record and allow identification of short polarity zones especially in the upper part of the section were the sedimentation rates are very low (~2m/Ma) The component magnetization directions determined from u-channel measurements also gave more reliable and precise estimates of inclination (paleolatitude). Although the calculation of the paleomagnetic pole is hindered by the low precision of the cores' azimuth orientation, the excellent data from both u-channel and discrete samples allow determining of the paleolatitude of the Site for different ages with relatively high precision. Paleomagnetic data indicate that the paleolatitude of Site 1218 is increasing with time form nearly equatorial in the Oligocene to its present latitude. Within the precision given by the paleomagnetic method, this is in agreement with current predictions of plate motion.

Calcareous nannofossil assemblages from the first Paleocene/Eocene sections ever to be sampled in the central tropical Pacific (ODP Sites 1215, 1220 and 1221) were preliminary studied with the purpose of obtaining informations on the evolutionary turnovers associated with the P/E boundary time and the peculiar global climatic conditions. We have documented the distribution ranges of some taxa, as {\it Ericsonia, Discoaster, Fasciculithus, Rhomboaster} and {\it Tribrachiatus}. Data were obtained through quantitative analyses on the assemblages. These detailed analyses were mainly focused on the evolution of {\it Rhomboaster- Tribrachiatus} lineage in the lower Eocene interval, and on the stratigraphic relationship of these taxa with the genus {\it Fasciculithus}. We have documented the consistent occurrence of {\it Thoracosphaera} cysts at the P/E boundary interval. Thoracosphaerids are considered representatives of opportunistic flora, and blooms of these forms are observed in sediments immediately above the extinction horizon of the Cretaceous/Paleogene boundary. Their abundance at the P/E transition could document a change of critical boundary conditions in surface waters. The analyses on calcareous nannofossils from the Early Paleogene sediments recovered during ODP Leg 199 provide also a new set of data for the nannofossil biostratigraphy and biochronology at the P/E transition interval.

ODP Leg 199 drilled a latitudinal transect of sites across the position of the early Eocene equator, designed to study the evolution of the equatorial Pacific current and wind system as the Earth went from maximum Cenozoic warmth to initial Antarctic glaciations. The cruise recovered a biogenic sedimentary record of equatorial processes from the early Miocene to the late Paleocene, roughly from 18 to 56 Ma. Above the biogenic sediments are 10 m or more of nonfossiliferous clay, representing most of the Neogene interval. We found that equatorial deposition patterns were stable for the Eocene but very different from those of the Neogene. The Eocene is marked by a very shallow carbonate compensation depth (CCD) and radiolarian ooze sediments. In contrast, Pleistocene equatorial sediments are carbonate and diatom rich. The Eocene equatorial sedimentation regime was also much wider than modern, expanding in the middle Eocene to about 10 degrees north of the paleoequator. We interpret the Eocene sedimentary environment to indicate significantly more diffuse upwelling than is found in the modern ocean and a deeper-than-modern eastern Pacific thermocline. Eocene deep waters appear to have been well-oxygenated despite being much warmer than modern deep waters . There is an abrupt sedimentological transition coincident with the first major glaciation of Antarctica in the early Oligocene from Eocene equatorial conditions to proto-modern conditions. Over a time period of about 120 kyr the CCD dropped by more than 1.3 km and sedimentation focused into a narrow equatorial band similar to equatorial sedimentation in the Holocene equatorial Pacific. We interpret the change to mark the first Cenozoic appearance of the modern Pacific equatorial upwelling system. We also recovered examples of the Paleocene-Eocene boundary at 3 different drillsites from about 1 degree south of the 55 Ma paleoequator to 11 degrees north of it. The P-E boundary event, one of the largest carbon-isotope excursions of the Cenozoic, is represented by a carbonate-poor multi-colored sediment interval. Consistent banding between two sites more than 200 km apart suggest significant changes in deep ocean chemistry during this time interval.

ODP Leg 199 was the first leg in which reflectance spectra were routinely measured from sediment cores at an extended bandwidth (350-2500 nm) using light absorption spectroscopy (LAS). Precruise calibration of spectral features to local ground-truth samples enabled shipboard calculation of concentrations of calcite and opal, the two biogenic sediment components, and smectite and illite, the two main terrigenous sediment components. These mineral calculation transforms were refined postcruise with additional ground-truth samples. Using multiple regression and LAS mineralogy, the multi-sensor track physical properties data were converted into high-resolution mineralogy logs. These logs, as well as age and dry-bulk density, were used to calculate high-resolution carbonate, opal, and terrigenous mass accumulation rates (MAR) for each Leg 199 site. Plots of opal MAR versus paleolatitude show that during the Paleogene, the opal equatorial accumulation bulge extended to about 12 degrees N, whereas in the Neogene the bulge extended only to about 7 degrees N. Carbonate accumulation rates during the middle to late Eocene were very low except for a few isolated intervals (e.g., around 41 Ma). Carbonate accumulation rates in the Oligocene and early Miocene were much higher than in the Eocene, with the carbonate equatorial bulge extending to 4 degrees N. Terrigenous MAR are much more variable between adjacent sites, probably because of ocean bottom currents. A Pliocene increase in terrigenous accumulations in the north (20-25 degrees N) may correspond to an increase in the Asian dust flux that occurred ~2.6 Ma.

Latitudinal transects of eolian deposition can help define patterns of equatorial zonal winds during Paleogene warm periods and their movement in response to global climatic transitions of the Cenozoic. We examined geochemical and mineralogical data from a number of piston cores and ODP drill sites in the tropical and subtropical Pacific Ocean. In the modern Pacific, dust deposited beneath the northeast trade winds reflects Asian provenance and is likely transported back west through the trade wind system via input from the mid-latitude westerly winds. The amount of dust supplied from American source regions is an order of magnitude lower and has limited influence on the dust record in the offshore pelagic realm of the Pacific. The inter-tropical convergence zone (ITCZ) forms an effective barrier to inter-hemispheric dust transport and marks the southern boundary of the Asian dust component. Just south of the ITCZ, dust is transported by southern trade winds predominantly from andesitic source regions of Central and South America. During warm periods of the early Paleogene, andesitic sources appear to dominate eolian deposition throughout the central and equatorial Pacific. Two hypotheses are offered to explain this observation. First, increased andesitic input is associated with trade wind transport from a North American provenance because Asian dust flux, which overwhelms this component in the modern Pacific, was significantly reduced at this time. Mineralogical data collected by light-absorption spectroscopy techniques on bulk sediments recovered during ODP Leg 199 supports this scenario showing increased illite/smectite ratios during the late Cenozoic near the time when Asian dust flux increased. Alternatively, the increased andesitic component during the Paleogene may reflect eolian deposition beneath the southern trade winds with the position of the ITCZ at a latitude as far north as perhaps 25°N. Data from clay mineralogy (from XRD), elemental geochemistry and Nd isotopic ratios from piston cores EW9709-01 and LL44-GPC3 support this hypothesis and show a transition to Asian-like dust provenance occurring by the early Miocene.

ODP Leg 199 was designated to collect sediments along a latitudinal transect in the Pacific Ocean to better understand Paleogene sedimentation patterns and the system of equatorial currents. At ODP Sites 1218 through 1220, the magnetic record of the Paleogene Equatorial sediments extends back to Polarity Chron C20r (Middle Eocene), providing an unprecedented record of Paleogene magnetostratigraphy in Equatorial Pacific sediments. Paleomagnetic data were acquired on the JOIDES-Resolution pass-through cryogenic magnetometer from archive halves of core sections. Ongoing analysis on u-channels corroborates the polarity pattern obtained on the shipboard magnetometer. Natural Remanent Magnetization was measured at 5-cm intervals for each core section, and was followed by four to five steps of alternating field demagnetization up to a maximum of 15 or 20 mT. In addition, shipboard and shore-based measurements of discrete samples were also carried out, including alternating field and thermal demagnetization. All measured lithologies, including an upper red clay, radiolarian ooze and nannofossil ooze/chalk yield reproducible results and have a moderate magnetization intensity, well above the noise level of the cryogenic magnetometer. Stepwise demagnetization of discrete samples indicates that the Characteristic Remanent Magnetization (ChRM) is stable and well defined for the most part of the sedimentary record. The obtained high-resolution magnetic stratigraphy allows to cross-calibrate magnetic reversal stratigraphy with biostratigraphy, including the placement of the Eocene-Oligocene and Oligocene-Miocene boundaries. Overall, results from Leg 199 provide the first complete magnetobiostratigraphic record for the Middle Eocene through the Pliocene in the Equatorial Pacific Ocean. A particularly important aspect of Leg 199 was to establish the latitudinal plate motion of the Equatorial Pacific, based on paleomagnetic data. ChRM directions for the demagnetized discrete samples are used to construct the paleolatitudinal evolution of Leg 199 sites. A progressive northward displacement of the Pacific Plate in the Paleogene, which places the equatorial mound of biogenic sediment in northern latitudes and moves sediments out of the high sediment flux area, is established from the analysis of paleomagnetic inclinations.

The broad mound of sediments found in the equatorial Pacific contains a detailed and complex record of the history of equatorial divergence, trade wind strength, biogeochemical fluxes, and biologic evolution. To extract this history from the biogenic sediments of this region the recovery of undisturbed and complete sections is required. Also required is the development of a detailed chronostratigraphy with which we can determine both the times and rates of paleoceanographic and paleoclimatic change. As this mound of sediment has ridden northward on the Pacific crust the most biogenic parts of the lower Cenozoic sediments have gradually moved from under the region of high flux rates at the divergence center. Now they lie within the reach of APC coring on the JOIDES Resolution. The sections recovered on Leg 199 form a paleolatitude transect from about 4.5$°S to 18.5$°N. Study of these sections has given us a well documented magnetic stratigraphy back into the Eocene, good calcareous nannofossil stratigraphy for the lower Miocene, Oligocene, and early Eocene, and excellent radiolarian stratigraphy from the lower Miocene through the middle Eocene. In addition we recovered good the Miocene/Oligocene and Eocene/Oligocene boundaries in an equatorial setting and LPTM sections near basement at three different sites. These results have allowed a more certain assignment of ages of biostratigraphic events and an opportunity to develop orbitally tuned time scales in sections from the lower Miocene down through the Oligocene. The initial estimates of sediment accumulation rates in the radiolarian oozes indicate variation by a factor of three from upper to middle Eocene times. Mapped patterns of sediment accumulation in the Eocene using both ODP Leg 199 and older DSDP data indicate at least two latitudinal zones of maxima in accumulation rates. Determination of the exact latitudes of these zones awaits further study.