abstract: The present understanding of the formation and evolution of the earliest bodies in the Solar System is based in large part on geochemical and isotopic evidences contained within meteorites. The differentiated meteorites (meteorites originating from bodies that have experienced partial to complete melting) are particularly useful for deciphering magmatic processes occurring in the early Solar System. A rare group of differentiated meteorites, the angrites, are uniquely suited for such work. The angrites have ancient crystallization ages, lack secondary processing, and have been minimally affected by shock metamorphism, thus allowing them to retain their initial geochemical and isotopic characteristics at the time of formation. The scarcity of angrite samples made it difficult to conduct comprehensive investigations into the formation history of this unique meteorite group. However, a dramatic increase in the number of angrites recovered in recent years presents the opportunity to expand our understanding of their petrogenesis, as well as further refine our knowledge of the initial isotopic abundances in the early Solar System as recorded by their isotopic systematics. Using a combination of geochemical tools (radiogenic isotope chronometers and trace element chemistry), I have investigated the petrogenetic history of a group of four angrites that sample a range of formation conditions (cooling histories) and crystallization ages. Through isotope ratio measurements, I have examined a comprehensive set of long- and short-lived radiogenic isotope systems (26Al-26Mg, 87Rb-87Sr, 146Sm-142Nd, 147Sm-143Nd, and 176Lu-176Hf) within these four angrites. The results of these measurements provide information regarding crystallization ages, as well as revised estimates for the initial isotopic abundances of several key elements in the early Solar System. The determination of trace element concentrations in individual mineral phases, as well as bulk rock samples, provides important constraints on magmatic processes occurring on the angrite parent body. The measured trace element abundances are used to estimate the composition of the parent melts of individual angrites, examine crystallization conditions, and investigate possible geochemical affinities between various angrites. The new geochemical and isotopic measurements presented here significantly expand our understanding of the geochemical conditions found on the angrite parent body and the environment in which these meteorites formed. / Dissertation/Thesis / Ph.D. Geological Sciences 2012

abstract: During the early Solar System many physiochemical processes were taking place that would shape the formation and evolution of rocky bodies. Growth of these rocky objects was rapid, with some growing to sizes of 10s – 1000s km (“planetesimals”) in the first few million years. Because these objects formed early, they contained sufficient 26Al (an isotope of Al with a short half-life of ~705,000 yrs) to heat the interiors to melting temperatures, resulting in the formation of the first igneous rocks in nascent Solar System. Depending on the size and time of accretion, some bodies experienced high degrees of melting (with some having global magma oceans) while others experienced lower degrees of partial melting, and yet others did not experience any melting at all. These varying degrees of heating and melting processes on early-formed planetesimals produced a variety of achondritic meteorite types. These achondrites have bulk compositions ranging from ultramafic to basaltic, with some rare types having more highly “evolved” (i.e., high-SiO2) compositions. Determining the detailed chronology of their formation with fine time resolution is key for understanding the earliest stages of planet formation, and there are high resolution chronometers that are ideally suited for this application. Three such chronometers (i.e., the 26Al-26Mg, 53Mn-53Cr, and 207Pb-206Pb chronometers) are the focus of this work. Based on investigations of these chronometers in several achondritic meteorites, the implications for the formation and evolution of planetesimals in the early Solar System will be discussed. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2020

Many ecological and evolutionary processes have been described underlying natural selection but supporting evidence in wild settings is often lacking and our understanding remains incomplete. Using a multi-scale approach, I investigated expression of facultative den behavior (denning) among and within ursid species. Among species, lack of denning behavior was supported by relaxation of selection pressures of seasonal food availability due to realization of two sources of ecological opportunity; colonization of new habitat and adaptation of key innovations. Of denning species, I found evidence of adaptive ecological plasticity in den chronology among and within populations consistent with relaxed selective pressures influencing seasonal food availability and energetic budgets. I supported these finding using indices of fitness and established ecological theory. Further knowledge of organismal response to selection pressures has practical applications in predicting responses to novel and fluctuating pressures and aids in our understanding of the complexities of ecology and evolution.

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The basic principles of relative and absolute chronology are presented in this introduction as they form the foundation upon which the collection of papers, published in the present and subsequent issue of the Bulletin, base their chronological and cultural schemes. The goal here is to compare and contrast these principles with common misunderstandings and misuses. The need for empirical data for the construction of chronological sequences is stressed in order to place them within a single periodification scheme. Another topic of concern is a coherent terminology rather than the use of different terms with different meanings. Lastly, the papers in these two issues are focused on "The Formative Period: Recent Approaches and Evidence". / En esta introducción se presentan los principios de la cronología relativa y absoluta, ya que estos forman la base para el conjunto de trabajos reunidos en este y el siguiente número del Boletín, con el propósito de señalar malentendidos y usos poco precisados heredados de antaño. Se enfatiza la necesidad de exponer los datos empíricos en la construcción de las cronologías y secuencias para insertarlas en un sistema de periodización general. Parte de esta discusión es, también, la terminología, que debería destacarse por su coherencia en vez de que se cuente con opciones más o menos libres de expresiones con significados diversos. Por último, se presentan los trabajos incluidos en los dos números dedicados al tema "El Periodo Formativo: enfoques y evidencias recientes".

This thesis provides an analysis of annalistic writing in Normandy between c. 1050 and c. 1225. It examines three principal groups of texts which were written and copied in religious institutions throughout the duchy from the mid eleventh century, before being transmitted beyond its borders into France and England. Its purpose is to address a significant gap in modern scholarship by establishing the origin, development and purpose of annalistic writing in Normandy and to consider the contribution of the texts to our understanding of Norman history in this period . The thesis consists of three main parts, followed by two appendices. Part I addresses the annals of Rouen, which were first written in Rouen cathedral chapter c. 1054/5 and which subsequently became the base text for one family of Norman annals. It presents a model of composition, outlining stages of redaction, sources used in its production and textual development down' to c. 1225. The text is also examined within the context of institutional and historiographical developments in the cathedral chapter of Rouen in the same period. Part 11 addresses the monastic annals of Normandy, outlining patterns of dissemination around the duchy and analysing each text in turn . Part II A considers the Rouen family of annals, Part II B the Bee family and Part II C the 'Fecamp' family . Finally, Part Ill considers the contribution of this analysis to modern scholarship. It examines what the annals can tell us about the nattlre and purpose of historical writing in Norman religious communities; and discusses how the texts can be used to enhance our knowledge of Norman history at both the institutional and the duchy-wide level. The thesis also includes a general introduction and conclusion, a bibliography, several diagrams and two technical appendices which provide an overview of the manuscripts in which the Norman annals are now preserved.

Herb- or shrub-chronology, a technique adapted from dendrochronology, is the study of the annual growth rings in roots of certain perennial dicotyledonous plants. The presence of annual growth increments in high-elevation plants is significant as it highlights the applicability of herbchronology for climatic, ecological and geomorphologic applications in alpine and other extra-arboreal regions. For alpine sites along the eastern crest of the Sierra Nevada range I present the first shrub-ring chronologies of the species Linanthus pungens (Torr.) J.M. Porter & L.A. Johnson. L. pungens individuals were collected at, and are especially ubiquitous at rock glacier sites in north-east trending glacial-cirque valleys. Rock glaciers are an increasingly recognized and studied feature on the alpine landscape, supporting floristically diverse plant populations, distinct thermal regimes decoupled from the external air and perennial water sources fed by interstitial ice. These landforms are expected to be refugia for alpine flora and fauna in some regions for projected warmer and drier climates. To evaluate plant growth on rock glaciers as compared to adjacent talus slopes in the central Sierra Nevada range of California, USA, a series of five cirque basins were selected as sites for paired rock glacier- talus slope vegetation comparisons. Vegetation cover, species richness, diversity measures and plant functional traits were recorded at ten sites (five rock glaciers, five talus slopes) along a 100-kilometer latitudinal span of the eastern slope of the Sierra Nevada range. Canonical correspondence analysis was used to evaluate general patterns in cover, diversity and functional traits for the 10 sites and inform subsequent statistical analyses. Both vegetation cover and species richness were significantly greater on rock glacier sites than on adjacent talus slopes even though mean slope values for the rock glacier sites were higher. Significantly, for the present study, rock glaciers support a higher number of the species Linanthus pungens, a climatically sensitive, long-lived alpine sub-shrub, showing that these periglacial landforms are not only floristically distinct but are also habitats containing natural climate archives useful to the field of herbchronology. L. pungens shrub-ring chronologies are determined to be distinct from Pinus albicaulis chronologies growing at the same five sets of sites in the Sierra Nevada study location. P. albicaulis (PIAL) tree-ring chronologies and L. pungens (LIPU) shrub-ring chronologies were constructed for four cirque basin sites. Comparisons were made between chronologies based on growth form (shrub or tree) and site, and on chronology response to average monthly temperature, total monthly precipitation and April 1 snowpack values. Chronologies are significantly more similar to other chronologies of the same growth form (PIAL-PIAL or LIPU-LIPU) than are same-site chronologies of different growth form (i.e. PIAL-LIPU chronologies) (p < 0.05). This holds true for comparisons based on Pearson’s correlation coefficients or Gleichläufigkeit (GLK) values. Growth response to monthly temperature and precipitation values is highly variable for same-site chronologies and also for same growth form chronologies. Topographical position and proximity to treeline was held constant at all sites so differences in climate-growth response within sites and within species may be attributed to factors that are unrealized in the sampling design. Based on composite climate anomaly maps, wide ring widths in PIAL chronologies occur after average winter and spring precipitation and with warm growing seasons while narrow PIAL rings fall after wet springs and with average summer temperatures. Years in which all LIPU rings are wide are found to occur during warm dry springs and growing seasons while years in which all LIPU rings are narrow occur in conjunction with wet winters and springs. Investigation into the longest and most replicated chronology at the Barney Lake (BL) site allowed a climate-growth comparison over a longer period of time (the BL chronology is 112 years in length with sufficient sample replication (EPS > 0.85) to capture a robust common signal from 1952 through 2007). Marker years in the BL chronology correspond to drought (wide rings) and persistent snowpack (narrow rings). Response function analysis indicates significant correlations with July minimum temperatures and the previous year's November precipitation. Increase in the radial growth of the taproot of L. pungens at BL has not decreased over the past century and is more highly correlated to temperature (positively) and snowpack and precipitation (negatively) during the latter half of the chronology period. Predictions of decreasing snowpack and warming temperatures for the alpine Sierra Nevada could indicate increased shrub growth over the next century and possible shrub range expansion if unprecedented drought does not prove to limit growth in the future. Work at BL and the other four alpine L. pungens chronology locations demonstrate a potential for additional research on climate-shrub growth interactions and in particular for investigations into climate controls on upper shrubline growth and movement in the Sierra Nevada range in California.

The long warming transition from the Last Ice Age into the present Interglacial period, the last deglaciation, holds the key to our understanding of future abrupt climate change. In the last decades, a great effort has been put into deciphering the linkage between freshwater fluxes from melting ice sheets and rapid shifts in global ocean-atmospheric circulation that characterized this puzzling climate period. In particular, the regional expressions of climate change in response to freshwater forcing are still largely unresolved. This projects aims at evaluating the environmental, hydro-climatic and oceanographic response in the Eastern North Atlantic domain to freshwater fluxes from the Scandinavian Ice Sheet during the last deglaciation (~19,000-11,000 years ago). The results presented in this thesis involve an overview of the regional representations of climate change across rapid climatic transitions and provide the groundwork to better understand spatial and temporal propagations of past atmospheric and ocean perturbations. Specifically, this thesis comprises i) a comparison of pollenstratigraphic records from densely 14C dated lake sediment sequences, which provides insight into the regional sensitivity of North European vegetation to freshwater forcing in the Nordic Seas around the onset of the Younger Dryas stadial (~12,900 years ago); ii) a reconstruction of North European hydro-climate, which, together with transient climate simulations, shed light on the mechanisms and regionality of climate shortly prior to the transition into the Younger Dryas stadial; iii) studies of a ~1250-year long glacial varve chronology, which provides an accurate timing for the sudden drainage of proglacial freshwater stored in the former ice-dammed Baltic Ice Lake into the North Atlantic Ocean; iv) a 5000-year long terrestrial-marine reconstruction of Eastern North Atlantic hydro-climate and oceanographic changes that clarifies the hitherto elusive relationship between freshwater forcing and the transient behaviour of the North Atlantic overturning circulation system. The results presented in this thesis provide new important temporal constraints on the events that punctuated the last deglaciation in Northern Europe, and give a clearer understanding of the ocean – atmosphere – ice-sheet feedbacks that were at work in the North Atlantic. This increases our understanding of how the Earth climate system functions in more extreme situations. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.</p>

Identifying connections between land use, population change, and natural and human-induced environmental change in ancient societies provides insights into the challenges we face today. This dissertation presents data from archaeological research at the ancient Maya center of Uxbenká, Belize, integrating chronological, geomorphological, and settlement data within an ecological framework to develop methodological and theoretical tools to explore connections between social and environmental change or stability during the Preclassic and Classic Period (~1000 BC to AD 900). High-precision AMS 14C dates from Uxbenká were integrated with stratigraphic information within a Bayesian framework to generate a high-resolution chronology of sociopolitical development and expansion in southern Belize. This chronology revises the previous understanding of settlement and development of Classic Maya society at Uxbenká and indicates specific areas of investigation to elucidate the Late and Terminal Classic periods (AD 600-900) when the polity appears to disintegrate. A geoarchaeological record of land use was developed and interpreted with respect to regional climatic and cultural histories to track landscape transformations associated with human-environment interactions at Uxbenká. The first documented episode of landscape instability (i.e., erosion) was associated with farmers colonizing the area. Later, landscape stability in the site core parallels Classic Period urbanization (AD 300-900) when swidden agriculture was likely restricted in the core. Another erosional event followed political disintegration as farmers resumed cultivation in and around the abandoned city. Maize yields derived from contemporary Maya farms in the area were used to estimate the maximum population size of Uxbenká during its Classic Period peak. The maximum sustainable population is estimated between 7500 and 13,000, including a potential population of ~525 elites in the core, assuming low levels of agricultural intensification. This accords well with the lack of archaeological evidence for intensive land management during the Classic Period (e.g., terraces). An ecological model developed using maize productivity and other environmental/social datasets largely predicts the settlement pattern surrounding Uxbenká. Settlements in marginal areas may be evidence of elite intra-polity competition during the Late Preclassic Period (ca. AD 1-300), though it is possible that marginal areas were settled early as garrisons to mediate travel into the site core.