Discovery of a Plains Caldera Complex and Extinct Lava Lake in Arabia Terra, Mars: Implications for the Discovery of Additional Highland Volcanic Source Regions

Several irregularly shaped topographic depressions occur near the dichotomy boundary in northern Arabia Terra, Mars. The geomorphology of these features suggests that they formed by collapse, opposed to meteor impact. At least one depression (approx.55 by 85 km) displays geologic features indicating a complex, multi-stage collapse history. Features within and around the collapse structure indicate volcanic processes. The complex occurs within Hesperian ridged plains of likely volcanic origin and displays no crater rim or evidence for ejecta. Instead the depression consists of a series of circumferential graben and down-dropped blocks which also display upper surfaces similar to ridged plain lavas. Large blocks within the depression are tilted towards the crater center, and display graben that appear to have originally been linked with circumferential graben outside of the complex related to earlier collapse events. A nearly 700 m high mound exists along a graben within the complex that might be a vent. The deepest depression displays two sets of nearly continuous terraces, which we interpret as high-stands of a drained lava lake. These features appear similar to the black ledge described during the Kilauea Iki eruption in 1959. A lacustrine origin for the terraces seems unlikely because of the paucity of channels found in or around the depression that could be linked to aqueous surface processes. In addition, there is no obvious evidence for lacustrine sediments within the basin. Together with the presence of significant faulting that is indicative of collapse we conclude that this crater complex represents a large caldera formed in the Late Noachian to Early Hesperian. Other linear and irregular depressions in the region also might be linked to ancient volcanism. If that hypothesis is correct, it suggests that northern Arabia Terra could contain a large, previously unrecognized highland igneous province. Evacuation of magma via explosive and effusive activity produced localized collapse, might have contributed to nearby ridged plains, and pyroclastic materials erupted from these vents might have supplied sediments in fretted terrain and other deposits. The recognition of volcanoes within Arabia Terra expands the known extent of Noachian-Hesperian volcanism to cover much of the preserved martian highland crust

Income Poverty in Canada: Recent Trends among Canadian Families 1981-2002

Abstract not availabl

Family Structures and Children’s Behavioral Problems: A Latent Growth Curve Analysis

The current article analyzes 1994-2000 data from the Canadian National Longitudinal Survey of Children and Youth to examine the relevance of family structures to trajectories of parental reports on hyperactivity - inattention among elementary school aged children. A latent growth modelling approach is used to compare children living in intact families, lone-parent families, stepfamilies, and families where parents divorced or separated. The results highlight the apparent advantages to living in intact families and the slightly greater risks experienced by children living in stepfamilies. Children in lone-parent families, while experiencing an initial disadvantage, displayed a similar trajectory on hyperactivity to children in intact families over the 1994-2000 period. With regard to the children of divorce, the current study finds little evidence of a predisruption effect, as the children whose parents divorce or separate over 1994- 2000 appear initially no worse off then children whose parents stay together

Clays and Carbonates in a Groundwater-Fed 3.8 Ga Martian Lake: Insights to Subsurface Habitability on Mars

On Earth, the deep biosphere remains a largely unexplored, but clearly important carbon reservoir. Results from some uplifted central peaks in craters on Mars indicate that substantial carbon was also present at depth and might have helped sustain a deep biosphere. In fact, many factors relevant to deep biosphere habitability are more favorable on Mars than on Earth (e.g. porosity of the crust, geothermal gradient). Future exploration of Mars should include landing sites where materials have been exhumed from depth by meteor impact or basins where subsurface fluids have emerged, carrying clues to subsurface habitability. One of the most astrobiologically interesting sites on Mars McLaughlin Crater, a 93 km-diameter impact crater that formed approximately 4 b.y. ago. On the floor of the crater is a stratigraphic section of subhorizontal, layered sedimentary rocks with strong spectroscopic evidence for Fe-rich clay minerals and Mg-rich carbonates, which we interpret as ancient lacustrine deposits. The fluids that formed these materials likely originated in the subsurface, based on the paucity of channels leading into the crater basin and the fact that this is one of the deepest basins on Mars - a good candidate to have experienced upwelling of subsurface fluids. Therefore, the deposits within McLaughlin crater provide insight into subsurface processes on Mars. In this presentation, we will discuss the habitability of the martian subsurface as well as the geology of McLaughlin Crater and the possibility to detect biomarkers at that site with a future landed mission

The Diversity Challenge for Higher Education in Canada: The Prospects and Challenges of Increased Access and Student Success

With the shifting demographics of societies such as the United States and Canada, access to higher education presents a variety of challenges to ensure that universities are able to meet the challenges associated with increased student diversity on campus. The current paper reviews first the literature on the linkages between social inequality and education, before turning to an examination of Canadian data with respect to access issues and the possible barriers to increasing diversity among postsecondary institutions. The evidence reveals that first-generation students and those whose parents did not attend university, Aboriginal peoples, and students with disabilities (among others) continue to be underrepresented in postsecondary education. At the same time, the paper argues that while institutions of higher learning can facilitate improved access, they must commit to developing support services and a more welcoming and inclusive environment in order to ensure student retention and success among an increasingly diverse student population. The paper concludes with a discussion of “best practices” from the perspective of a predominantly undergraduate, liberal arts institution in southern Ontario

High-resolution investigations of Transverse Aeolian Ridges on Mars

Transverse Aeolian Ridges (TARs) are the most pervasive aeolian feature on Mars. Their small size requires high-resolution data for thorough analyses. We have utilized Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and High Resolution Image Stereo Experiment (HiRISE) images, along with MRO Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectroscopic data to study TARs in detail. TAR deposits, along with related dark dune material and layered terrains, have been mapped in six study areas in order to identify sediment pathways and determine whether TARs are sourced locally or from global wind-borne materials. TAR morphology and orientation were mapped in grids within each study area; the results show that TARs are probably locally sourced. We constructed four HiRISE Digital Terrain Models (DTMs) to measure TAR heights, widths, spacing, areas, symmetry, and to calculate sediment volumes. Results show that TARs have average heights of ∼1.5 m, are very symmetrical, and are similar in form to terrestrial megaripples. Orthorectified HiRISE images taken 3 years apart were analyzed for TAR movement and none was found. Superposed craters on equatorial TARs give ages of ∼2 Ma, suggesting that these are relatively ancient and generally inactive aeolian deposits. CRISM data were analyzed over TAR deposits, dark dune material, and light-toned terrains. Although the surfaces were somewhat obscured by dust cover, the results did not show any remarkable difference between TARs and other deposits. We conclude that TARs may be sourced from local materials and form in a similar way to terrestrial megaripples

Identification of iron in Earth analogues of Martian phyllosilicates using visible reflectance spectroscopy: Spectral derivatives and color parameters

A range of phyllosilicate compositions have been detected spectroscopically on Mars, but the largest fraction by far corresponds to clay minerals rich in Fe and Mg. Given that most of our understanding of Martian clays comes from remote sensing data, it is critically important to explore the details of how compositional variation affects spectral features of phyllosilicates. The greatest efforts have focused so far on near-infrared (NIR) spectroscopy. Recently, ambiguities have been detected in the NIR spectra of 2:1 phyllosilicates with intermediate FeeMg content that preclude mineral and chemical discrimination. Such ambiguities highlight the relevance of exploring the visible spectral range as a complementary tool to characterize Martian phyllosilicates precisely. This article reports the investigation of laboratory reflectance spectra (330–800 nm) from 34 Earth analogues of Martian phyllosilicates with a wide range of MgeFe composition, including nontronite, celadonite and saponite end-members, as well as interstratified glauconite-nontronite, talc-nontronite, and talc-saponite. The spectra indicated the presence of Fe(III) by absorption modulations and a decrease in total reflectance, especially in samples with tetrahedral Fe(III). Absorption bands at 370 and 420 nm were diagnostic of octahedrically and tetrahedrally coordinated Fe(III), respectively. Band amplitudes in the second derivative of the Kubelka-Munk function correlated positively with Fe(III) content (R2 > 0.8). Standard color analyses of the visible reflectance spectra under the CIE illuminant D65 indicated that the CIELAB color parameter a*10 was positively correlated with tetrahedral Fe(III), b*10 was positively correlated with octahedral Fe(III), and L*10 was negatively correlated with Fe(III) in both structural sites. Because Fe(II) was in relatively low amount, it did not provide clear spectral evidence. Multiple regression models using the amplitude of the diagnostic absorption bands predicted well absolute Fe content in the phyllosilicates (R2=0.89) and the ratio Fe/(Fe+Mg+Al) (R2=0.84). CIELAB color parameters improved the prediction of total Fe (R2=0.92) and the ratio Fe/(Fe+Mg+Al) (R2=0.93). Application of these analyses to Martian data has challenges set by Fe oxide dust coating and spatial and spectral resolution. However, these results mark an avenue to develop testable tools using visible-wavelength spectral data from both satellite and lander probes to help establishing Fe content and mineral identification of Martian phyllosilicates

The Tree of Knowledge: System A New Map for Big History

This article summarizes the Tree of Knowledge (ToK) System (Henriques, 2003; 2011), and compares and contrasts its depiction of cosmic evolution as four “dimensions of existence” (i.e., Matter, Life, Mind and Culture) with Big History’s eight thresholds of complexity. Both systems share the concern with the current fragmentation in academic knowledge and advocate for a more consilient and integrative vision that places the disciplines in coherent relationship to each other, and both views argue that such efforts are needed to advance wise decision making in the context of the accelerating rate of change. The major differences between the two perspectives are found in how the ToK conceptualizes the different dimensions of existence. Following Matter, the dimensions of Life, Mind and Culture are seen as emerging as a function of different semiotic or information processing systems that give rise to strongly emergent properties. In addition, given its emphasis on psychology and the mental dimension of existence, the ToK highlights some aspects of cosmic evolution that have not been featured prominently in most models of BH. The article ultimately suggests that there is potential for a fruitful synergy between the historical emphasis of BH with the more psychological focus of the ToK System