A Study Of Undergraduate Students Alternative Conceptions Of Earths Interior Using Drawing Tasks

Learning fundamental geoscience topics such as plate tectonics, earthquakes, and volcanoes requires students to develop a deep understanding of the conceptual models geologists use when describing the structure and dynamics of Earths interior. Despite the importance of these mental models underlying much of the undergraduate geoscience curriculum, surprisingly little research related to this complex idea exists in the discipline-based science education research literature. To better understand non-science-majoring undergraduates' conceptual models of Earths interior, student-generated drawings and interviews were used to probe student understanding of the Earth. Ninety-two semi-structured interviews were conducted with non-science-major college students at the beginning of an entry-level geology course at a large Midwestern university. Students were asked to draw a picture of Earths interior and provide think-aloud explanations of their drawings. The results reveal that students hold a wide range of alternative conceptions about Earth, with only a small fraction having scientifically accurate ideas. Students understandings ranged from conceptualizing Earths interior as consisting of horizontal layers of rock and dirt, to more sophisticated views with Earths interior being composed of concentric layers with unique physical and chemical characteristics. Processes occurring within Earth, such as "convection," were rarely mentioned or explained. These results provide a first-steps basis from which to further explore college students thinking and contribute to the growing body of knowledge on earth science teaching and geoscience education research

Millipeds (Arthropoda: Diplopoda) of the Ark - La - Tex. VI. New Geographic Distributional Records from Select Counties of Arkansas

We continue to report, in the sixth of a series of papers, new geographic records for millipeds of the state, including noteworthy records for some taxa collected from Crowley’s Ridge in eastern Arkansas. This contribution documents 47 new co. records and includes records for 19 species within 9 families and 5 orders. More uncommon millipeds found included Okliulus carpenteri (Parajulidae), Eurymerodesmus newtonus (Eurymerodesmidae), Pseudopolydesmus minor (Polydesmidae) and undescribed species of Ethojulus (Parajulidae) and Nannaria (Xystodesmidae). Undoubtedly, additional records will be reported in the future as several gaps in the distribution of Arkansas millipeds remain

The pedogenesis of tin- and sulfide-lode mineralization at True Hill, southwestern New Brunswick

The subvolcanic True Hill granite porphyry in southwestern New Brunswick is genetically related to the Beech Hill series of granites of Devono-Carboniferous age. Three True Hill (TH) greisenised granite porphyry cupolas host Bi-Sn-Mo-W mineralized zones that have similarities to the nearby W-Mo-Bi orebodies at Mount Pleasant (MP). Tin-bearing lodes (0.03 to 0.66 wt, % Sn) are developed along faults and fractures that cut both mineralized (Bi-Sn-Mo-W) and unmineralized True Hill granite porphyry and enclosing metasedimentary rocks of the Waweig Formation. Within these lodes, particularly the central Main lode, two types of mineralization are present, an early chlorite-sulfide assemblage (Stage 1) and a later hematite-phengite-cassiterite assemblage (Stage 2) that replaces, in part, the earlier Stage 1 assemblage. The Stage 1 assemblage consists of Fe-rich septechlorite, pyrite, low-Fe sphalerite, magnetite, chalcopyrite, galena, Pb-Bi sulfides, tennantite, arsenopyrite and native Ag. Fe-Mg-Mn metasomatism responsible for chloritization was coincident with leaching of alkali and alkali-earth elements during feldspar hydrolysis. The Stage 1 assemblage (chl-sulfide) was formed at low temperature (<200°C) and low oxygen fugacity. The Stage 2 assemblage includes hematite, phengite, cassiterite and monazite with minor late quartz and fluorite. This assemblage was deposited at slightly higher temperatures (200"-300°CX higher oxygen fugacity (above hematite magnetite buffer) and at moderate pH 's (<musc-Kfs buffer). The overprinting of Stage 2 assemblages on portions of Stage 1 locally produces complex textures within the lodes at True Hill. The composition of both Stage 1 and 2 assemblages in the lodes is controlled by the (i) host rock composition and (ii) the mineralizing hydrothermal fluids. The deposition of Sn and LREE from Stage 2 fluids formed cassiterite and monazite along the reaction front between Stage 2 assemblages and chlorite-sulfide (Stage 1) and granite. Deposition of cassiterite probably occurred in response to (i) an increase in the Fe-Cl complexing at the expense of Sn- and LREE-C1 complexes during interation with Stage 1 assemblages, (ii) an increase in pH due to the feldspar hydrolysis in the granite and (iii) cooling of the fluid by the host rock. Although uneconomic, tin-sulfide lodes at True Hill have similarities with lodes developed within the North Zone of Mount Pleasant (New Brunswick) and Cornwall (England). However, the association of hematite and phengite with cassiterite mineralization is unique to this deposit RÉSUMÉ Le porphyre granitique subvolcanique de True Hill (Nouveau-Brunswick méridional) est lié par sa genèse au cortege granitique dévono-carbonifère de Beech Hill. Trois coupoles de porphyre granitique de True Hill (TH) altéré en greisen renferment des zones minéralisées en Bi-Sn-Mo-W et qui montrent des similitudes avec les gisements voisins de W-Mo-Bi présents a Mount Pleasant (MP). Des faisceaux filoniens porteurs d'étain (0,03 à 0,66% pds. Sn) s'installent le long de failles et de cassures recoupant les porphyres granitiques de True Hill, tant minéralises que stériles, ainsi que leur encaissant métasédimentaire (Formation de Waweig). Au sein de ces faisceaux, et surtout du faisceau central principal, on note deux types de minéralisation: un assemblage précoce à chlorite-sulfure (stage 1) et un assemblage tardif à hématite-phengite-cassitérite (stage 2) qui remplace en partie le premier. L'assemblage représentant le stage 1 consiste en de la septechlorite riche en Fe, de la pyrite, de la blende pauvre en Fe, de la magnétite, de la chalcopyrite, de la galène, des sulfures à Pb-Bi, de la tennantite, du mispickel et de l'argent natif. La métasomatose des Fe-Mg-Mn, dont provient la chloritisation, s'accompagne d'un lessivage des éléments alcalins et alcalino-terreux durant l’hydrolyse des feldspaths. L'assemblage denotant le stage 1 (chlorite-sulfures) se forma à basse température (<200°C) et faible fugacite d'oxygene. L'assemblage traduisant le stage 2 comporte de l'hématite, de la phengite, de la cassitérite, ainsi que de la monazite avec de faibles quantités de quartz et de fluorine tardifs. Cet assemblage fait inlervenir des températures un peu plus élevées (200°C a 300°C), une fugacité d'oxygène plus élevée (au-dessus du tampon hématite-magnétite) et des pH modérés (en-dessous du tampon des feldspaths potassiques de la muscovite). La surimpression des assemblages représentant le stage 2 sur des portions du stage 1 produit localement des textures complexes au sein des faisceaux filoniens de True Hill. La composition des assemblages dénotant tant le stage 1 que le stage 2 au sein de ces faisceaux est régie par: (i) la composition de l'encaissant et (ii) les étutdes minéralisateurs hydrothermaux. Le dépôt d'euin et de T.R. légères à paitir des fluides du stage 2 engendra de la cassitérite et de la monazite le long du front réactionnel, entre les assemblages témoins du stage 2, les chlorite-sulfures et le granite. Le dépôt de la cassitérite est probablement le fruit de: (i) une augmentation de la formation de complexes à Fe-Cl aux depens des complexes à Snet à Cl-T.R. légères durant l’interaction avec des assemblages du stage l,(ii)une élévation du pH par suite de 1 l’hydrolyse des feldspaths du granite, et (iii) le refroidissement du fluide par rencaissant Bien que de nature non économique, les faisceaux filoniens à étain et à sulfures présents à True Hill ne sont pas sans rappeler les faisceaux développés dans la Zone Nord de Mount Pleasant (Nouveau-Bnmswick) et à Cornwall (Angleterre). Cependant, ce gisement se singularise par l’association d'hématite et de phengite avec la minéralisation en cassitérite. [Traduit par le journal

Federal Environmental Law in the \u27New Federalism\u27 Era

As we wrote last year, the U.S. Supreme Court has shown considerable interest during the past decade in reconsidering many constitutional doctrines regarding federalism and congressional power. In a series of important decisions, always decided with the same five justices in the majority, the Court has begun to redefine the federal-state relationship and the scope of federal authority. The past term generally continued that trend, with one important commerce power decision, one significant Eleventh Amendment/Fourteenth Amendment decision, and a number of decisions that involve or affect federalism and the scope of federal power, although the Court sometimes relied on statutory interpretation to avoid serious constitutional issues. Part I of this article describes the most recent decisions

Federal Environmental Law in the \u27New Federalism\u27 Era

As we wrote last year, the U.S. Supreme Court has shown considerable interest during the past decade in reconsidering many constitutional doctrines regarding federalism and congressional power. In a series of important decisions, always decided with the same five justices in the majority, the Court has begun to redefine the federal-state relationship and the scope of federal authority. The past term generally continued that trend, with one important commerce power decision, one significant Eleventh Amendment/Fourteenth Amendment decision, and a number of decisions that involve or affect federalism and the scope of federal power, although the Court sometimes relied on statutory interpretation to avoid serious constitutional issues. Part I of this article describes the most recent decisions

Sequestering in String Theory

We study sequestering, a prerequisite for flavor-blind supersymmetry breaking in several high-scale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily sequester. The AdS/CFT dual description in terms of conformal sequestering plays an important role in our analysis, and we establish how sequestering works both on the gravity side and on the gauge theory side. We pay special attention to subtle compactification effects that can disrupt sequestering. Our result is a step toward realizing an appealing pattern of soft terms in a KKLT compactification