Vol. 1 Ch. 9 The Genealogical Connections between Particular Hopewellian and Mississippian Avian Motifs and Themes

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Pluto's lower atmosphere and pressure evolution from ground-based stellar occultations, 1988-2016

Context. The tenuous nitrogen (N2) atmosphere on Pluto undergoes strong seasonal effects due to high obliquity and orbital eccentricity, and has recently (July 2015) been observed by the New Horizons spacecraft. Aims. The main goals of this study are (i) to construct a well calibrated record of the seasonal evolution of surface pressure on Pluto and (ii) to constrain the structure of the lower atmosphere using a central flash observed in 2015. Methods. Eleven stellar occultations by Pluto observed between 2002 and 2016 are used to retrieve atmospheric profiles (density, pressure, temperature) between altitude levels of ~5 and ~380 km (i.e. pressures from ~ 10 μbar to 10 nbar). Results. (i) Pressure has suffered a monotonic increase from 1988 to 2016, that is compared to a seasonal volatile transport model, from which tight constraints on a combination of albedo and emissivity of N2 ice are derived. (ii) A central flash observed on 2015 June 29 is consistent with New Horizons REX profiles, provided that (a) large diurnal temperature variations (not expected by current models) occur over Sputnik Planitia; and/or (b) hazes with tangential optical depth of ~0.3 are present at 4–7 km altitude levels; and/or (c) the nominal REX density values are overestimated by an implausibly large factor of ~20%; and/or (d) higher terrains block part of the flash in the Charon facing hemisphere

An Event-Centered Perspective on Mound 2 at the Hopewell Earthworks

This article reports on our assessment of the events that resulted in Mound 2 at the Hopewell Earthworks, with a special focus on its two caches of blue-gray chert bifaces. Our analysis begins by examining the ritual practices associated with Mound 2, including the evidence for fire ceremonialism, extended burial regimes, and the ceremonial deposition of two biface caches. Initially, we focus on evidence of Scioto Hopewell fire ceremonialism on the lower floor under Mound 2, including the significance of the basin-shaped hearth found next to the lower cache of bifaces and several features that contained puddled-clay hearth fragments. We then examine the five burials found under Hopewell Mound 2, considering their grave goods and mortuary furniture. Next, we analyze the two biface caches and their resemblance to similar deposits. We also provide a preliminary assessment of the chert sources from which these bifaces were produced based on a reflectance spectroscopic analysis of 172 bifaces. Our subsequent discussion considers the historical intersection of these three aspects of Hopewell Mound 2 (i.e., fire ceremonialism, biface caches, and burials), including how Middle Woodland ceremonial situations gathered together and arranged increasingly complex assemblages in novel ways