Gender and physical geography in the United Kingdom

Summary This paper presents the results of a questionnaire survey of all higher education geography departments in the United Kingdom, in order to provide an overview of the current status of women employed in the discipline, particularly female physical geographers. The survey examined the position of female physical geographers of doctoral level and above, in terms of employment status, type of contract, career structure, research and teaching disciplines and successful grant applications. The publication records of female academic staff were also examined. The results of the survey demonstrate that women are under-represented in physical geography at all levels of the academic hierarchy and that the majority of female physical geography academic staff are below 40 years of age, and employed at the lecturer level on permanent contracts.     

Major thrust sheet in the Daqing Shan Mountains Inner Mongolia, China

Small thrust faults in the Daqing Shan that were previously mapped as separate structures belong to a single Mesozoic thrust, herein named the Daqing Shan thrust. It extends more than 155 km along the northern margin of the Daqing Shan, obliquely cutting the Daqing Shan along the western flank of the Jinluandian peak to the southeast and taking its way to Chayouzhongqi to the east. Kinematic markers indicate tectonic transport of the thrust sheet to the NNW. Minimum displacement, based on the observable outcrops, is 22 km, and the inferred thrusting distance may be larger than 35 km. The thrust sheet covers the whole eastern area of the Daqing Shan. The thrust truncates the E-W trending, somewhat older South-directed Panyanshan thrust and, therefore, the two faults are not as a result of counter thrusting. Such major intraplate tectonic deformation that occurred in the Inner Mongolia Axis or the Yin Shan latitudinal tectonic belt during late Jurassic time calls for deep thought on its tectonic significance in dynamics. It is most likely that the Daqing Shan thrust represents major intraplate shortening during Jurassic-Cretaceous closure of the Mongolo-Okhotsk ocean about 1000 krn away to the north. Project supported by the National Natural Science Foundation of Chlna (Grant No. 49070135) and by the Natlonal Science Foundation of the Unlted States (Grant No.EAR-9627909).     

Potential Effects of Global Warming on Waterfowl Populations Breeding in the Northern Great Plains

The Prairie Pothole Region (PPR) of the Northern Great Plains is the most important breeding area for waterfowl in North America. Historically, the size of breeding duck populations in the PPR has been highly correlated with spring wetland conditions. We show that one indicator of climate conditions, the Palmer Drought Severity Index (PDSI), is strongly correlated with annual counts (from 1955 to 1996) of both May ponds (R2 = 0.72, p < 0.0001) and breeding duck populations (R2 = 0.69, p < 0.0001) in the Northcentral U.S., suggesting the utility of PDSI as an index for climatic factors important to wetlands and ducks. We then use this relationship to project future pond and duck numbers based on PDSI values generated from sensitivity analyses and two general circulation model (GCM) scenarios. We investigate the sensitivity of PDSI to fixed changes in temperature of 0°C, +1.5°C, +2.5°C, and +4.0°C in combination with fixed changes in precipitation of -10%, +0%, +7%, and +15%, changes spanning the range of typically-projected values for this region from human-induced climatic change. Most (11 of 12) increased temperature scenarios tested result in increased drought (due to greater evapotranspiration under warmer temperatures) and declining numbers of both wetlands and ducks. Assuming a doubling of CO2 by 2060, both the equilibrium and transient GCM scenarios we use suggest a major increase in drought conditions. Under these scenarios, Northcentral U.S. breeding duck populations would fluctuate around means of 2.1 or 2.7 million ducks based on the two GCMs, respectively, instead of the present long-term mean of 5.0 million. May pond numbers would fluctuate around means of 0.6 or 0.8 million ponds instead of the present mean of 1.3 million. The results suggest that the ecologically and economically important PPR could be significantly damaged by climate changes typically projected. We make several recommendations for policy and research to help mitigate potential effects.     

Chlorine-36 and the initial value problem

 Chlorine-36 is a radionuclide with a half-life of 3.01×10⁵a. Most ³⁶Cl in the hydrosphere originates from cosmic radiation interacting with atmospheric gases. Large amounts were also produced by testing thermonuclear devices during 1952–58. Because the monovalent anion, chloride, is the most common form of chlorine found in the hydrosphere and because it is extremely mobile in aqueous systems, analyses of both total Cl^– as well as ³⁶Cl have been important in numerous hydrologic studies. In almost all applications of ³⁶Cl, a knowledge of the initial, or pre-anthropogenic, levels of ³⁶Cl is useful, as well as essential in some cases. Standard approaches to the determination of initial values have been to: (a) calculate the theoretical cosmogenic production and fallout, which varies according to latitude; (b) measure ³⁶Cl in present-day precipitation and assume that anthropogenic components can be neglected; (c) assume that shallow groundwater retains a record of the initial concentration; (d) extract ³⁶Cl from vertical depth profiles in desert soils; (e) recover ³⁶Cl from cores of glacial ice; and (f) calculate subsurface production of ³⁶Cl for water that has been isolated from the atmosphere for more than one million years. The initial value from soil profiles and ice cores is taken as the value that occurs directly below the depth of the easily defined bomb peak. All six methods have serious weaknesses. Complicating factors include ³⁶Cl concentrations not related to cosmogenic sources, changes in cosmogenic production with time, mixed sources of chloride in groundwater, melting and refreezing of water in glaciers, and seasonal groundwater recharge that does not contain average year-long concentrations of ³⁶Cl. Received, December 1996 · Revised, August 1997 · Accepted, August 1997     

Addition of magmatic volatiles into the hot spring waters of loowit canyon,Mount St. Helens,Washington, USA

Geochemical studies on cold meteoric waters, post-1980 hot spring waters, fumarole emissions from the dacite dome, and volcanic rocks at Mount St. Helens (MSH) from 1985 to 1989 show that magmatic volatiles are involved in the formation of a new hydrothermal system. Hot spring waters are enriched in ¹⁸O by as much as 2 and display enrichments in D relative to cold waters. A well-defined isotopic trend is displayed by the isotopic composition of a>400°C fumarole condensate collected from the central crater in 1980 (-33 D, +6 ¹⁸O), of condensate samples collected on the dome, and of cold meteoric and hot spring waters. The trend indicates that mixing occurs between local meteoric water and magmatic water degassing from the dacite dome. Between 30 and 70% magmatic water is present in the dome fumarole discharges and 10% magnatic water has been added to the waters of the hydrothermal system. Relations between Cl, SO₄ and HCO₃ indicate that the hot spring waters are immature volcanic waters formed by reaction of rocks with waters generated by absorption of acidic volcanic fluids. In addition, the B/Cl ratios of the spring waters are similar to the B/Cl ratios of the fumarole condensates (0.02), values of ¹³C in the HCO₃ of the hot springs (-9.5 to-13.5) are similar to the magmatic value at MSH (-10.5), and the ³He/⁴He ratio, relative to air, in a hot spring water is 5.7, suggesting a magmatic origin for this component.managed by Martin Marietta Energy Systems, Inc., under contract DE-AC05-84OR21400 with the US Department of Energy     

Joesmithite,a plumbous amphibole revisited and comments on bond valences

Summary Joesmithite is a complex clinoamphibole which contains at least 14 components in its formula. Its ideal formula would be PbCa₂ Mg₃ Fe ₂ ³⁺ (Si₆Be₂O₂₂) (OH)₂. It is monoclinic holosymmetric, an ordered derivative of theC2/m clinoamphiboles,a = 9.915(2),b = 17.951(4),c = 5.243(1)Å, = 105.95(2)°, Z = 2, space groupP2/a, D(obs) = 3.83(1), D(cal) = 3.91 g cm^-3. R = 0.056 for 2299 independent F₀.The cells of joesmithite and pargasitic amphibole were compared according to differences, , in their structure cells. The same procedure was applied to the margarosanite, PbCa₂Si₃O₉ and walstromite, BaCa₂Si₃O₉ pairs. In both pairs, the anion positions differed by 0.2 Å at most, but the Pb/A, Pb/Ba differences ranged from 0.4 to 0.6 Å. The lone pair Pb²⁺ cation responds according to the bond valence sums of its coordinating anions compared with its closed core counterpart.It appears that when the bond valence sums for the coordinating anions are different, Pb²⁺ moves toward the most underbonded anion. If the anion bond valence sums are equal for all vertices of the coordinating polyhedron (as in wulfenite, Pb²⁺Mo⁶⁺O₄), then Pb²⁺ does not shift.

---

Joesmithit, Neubearbeitung eines bleihältigen Amphibols und Kommentar zu den Bindungsstärken

Zusammenfassung Joesmithit ist ein komplex zusammengesetzter Klinoamphibol, der rumindest 14 Komponenten in seiner Formel aufweist. Die idealisierte Formel lautet PbCa₂Mg₃Fe ₂ ³⁺ (Si₆Be₂O₂₂)(OH)₂. Er ist monoklin holoedrisch und von den geordnetenC2/m-Klinopyroxenen abgeleitet,a = 9,915(2),b = 17,951(4),c = 5,243(1) Å,ß = 105,95(2)°, Z = 2, RaumgruppeP2/a, D(beob) = 3,83(1), D(ber) = 3,91 g cm^-3. R = 0,056 für 2299 unabhängige F₀.Die Elementarzellen von Joesmithit und einem pargasitischen Amphibol wurden in Bezug auf deren Struktur verglichen, ebenso jene von Margarosanit, PbCa₂Si₃O₉, und Walstromit, BaCa₂Si₃O₉, In beiden Paaren differieren die Positionen der Anionen um maximal 0,2 Å, die Unterschiede Pb/A = (Na, K, ) und Pb/Ba betragen 0,4 und 0,6 Å. Das ein einsames Elektronenpaar aufweisende Kation Pb²⁺ folgt den Bindungsstärken der koordinierenden Anionen im Vergleich zu den Pendents mit abgeschlossener Elektronenschale.Differieren die Bindungsstärken der koordinierenden Anionen, bewegt sich Pb²⁺ offensichtlich auf das am schwächsten abgesättigte Anion zu. Falls die Summe der Bindungsstärken an den Anionen in allen Richtungen des Koordinationspolyeders gleich sind (wie im Wulfenit, Pb²⁺Mo⁶⁺O₄), dann kommt es zu keiner Verschiebung des Pb-Atoms.

---

---

Dedicated to Prof. Josef Zemann, Keeper of the flame of chemical crystallography

---

Deceased

---

With 2 Figures     

Mars: Satellite origin and angular momentum

The origin of Phobos and Deimos is considered with a view to accounting for the existence of very small satellites with circular orbits in the Martian equatorial plane, and simultaneously for the suspected angular momentum deficiency of the Mars system. All models considered failed to satisfy at least one requirement, and the problem is considered more puzzling than is at first apparent. The Martian angular momentum deficiency, if physically significant, may be unrelated to the present satellites' origin, but might relate to a large ancient satellite, long ago destroyed. Accretion onto Mars of large amounts of asteroidal dust brought in by Poynting-Robertson drag may have some bearing on the angular momentum problem.     

Upper Yellowstone River Flow and Teleconnections with Pacific Basin Climate Variability during the Past Three Centuries

Climate variability, coupled with increasing demand is raising concerns about the sustainability of water resources in the western United States. Tree-ring reconstructions of stream flow that extend the observational record by several centuries provide critical information on the short-term variability and multi-decadal trends in water resources. In this study, precipitation sensitive Douglas-fir (Pseudotsuga menzeisii) tree ringrecords are used to reconstruct annual flow of the Yellowstone River back to A.D. 1706. Linkages between precipitation in the Greater Yellowstone Region and climate variability in the Pacific basin were incorporated into our model by including indices Pacific Ocean interannual and decadal-scale climatic variability, namely the Pacific Decadal Oscillation and the Southern Oscillation. The reconstruction indicates that 20th century streamflow is not representative of flow during the previous two centuries. With the exception of the 1930s, streamflow during the 20th century exceeded average flows during the previous 200 years. The drought of the 1930s resulted in the lowest flows during the last three centuries, however, this probably does not represent a worst-case scenario for the Yellowstone as other climate reconstructions indicate more extreme droughts prior to the 18th century.