Jenkins: A New Iron Meterorite from Missouri

Abstract Jenkins was found about 1946 and identified as a meteorite in 1965. The weight before sectioning was 122 lbs. It is a coarse octahedrite with irregular nodules of troilite and sizeable patches of graphite, schreibersite, and lawrencite.     

Challenges of forest governance in Madagascar

There has been a huge surge in interest in the preservation of Madagascar's forests in the past two decades, but despite the investment of hundreds of millions of dollars, the goal remains elusive. Recent legislation has given the government the authority to enter into contractual arrangements with communities for the management of the country's public forests, so it has become crucial to grapple with the significant challenges involved. This paper explores the enormity of the challenge of forest governance in Madagascar in an era of decentralization. By examining several forests in one part of the country, it reveals a dizzying range of forest types and forms of use and governance within a fairly small portion of the country. These examples make it apparent that the history of forest management in Madagascar constitutes a broad-ranging experiment with forest governance. Simply monitoring the dynamics of the forest canopy is a significant technical challenge. However, this pales in comparison to the difficulties inherent in explaining those dynamics and assessing the sustainability and equity of different management regimes. Of the forests considered in the study, those where the Malagasy state has partnered with international conservation and development organizations seem to stand out, both in terms of stabilized, or even growing, forest cover, as well as a balance of interests among users.     

Stratigraphic base level and fluvial architecture: Ericson Sandstone (Campanian), Rock Springs Uplift, SW Wyoming, USA

The concept of stratigraphic base level, or the ratio between accommodation and sediment supply (A/S ratio), has been used to analyse the Rusty and Canyon Creek Members of the Campanian Ericson Sandstone in the Rock Springs Uplift, SW Wyoming, USA. The Ericson Sandstone was deposited under fluvial to estuarine conditions in a foreland basin setting influenced both by Sevier-style (thrust belt) tectonism and by more local, Laramide-style, foreland uplifts. The depositional setting was situated several tens to a few hundred kilometres from the nearest shoreline. Therefore, sea level change at the contemporaneous shoreline probably had little, if any, influence on the development of the sedimentary architecture. The Rusty Member shows an alternation between incised valleys filled by multi-storey estuarine channel sandstones showing palaeoflow to the south and delta plain sediments with single-storey channels with no evidence of tidal influence, which show palaeoflow to the east. This cyclicity is interpreted as recording repeated uplift of the Wind River Range to the north, causing valley incision and reduction of the A/S ratio. During quiescent periods, the A/S ratio increased allowing the valleys to fill and delta plain conditions to be subsequently re-established because of increased sediment supply from the thrust belt in the west. A regional unconformity at the base of the Canyon Creek Member truncates the Rusty Member, and represents a significant reduction of the A/S ratio caused by Laramide tectonic uplift. The Canyon Creek Member is a multi-storey, multi-lateral fluvial channel sandstone, where channel preservation and thickness increase upwards, suggesting an increase of the A/S ratio. The Canyon Creek Member channels are interpreted to have been sinuous, meandering channels from the observed sedimentary structures and fill patterns, despite their sand-rich nature. It is argued that grain size is a poor indicator of channel planform, and that there was very low preservation potential for fine material because of a relatively low A/S ratio. The top of the Canyon Creek Member is a regionally correlative surface marking an abrupt increase of the A/S ratio. This surface is termed an expansion surface, denoting an abrupt increase in accommodation. The overlying Almond Formation shows a single-storey alluvial architecture with a very high preservation of fine-grained material. An assumed correspondence in time of the Late Absaroka thrust phase in the Sevier belt to the west and the formation of the sharp top of the Canyon Creek Member suggests that the thrust phase caused a basin-wide abrupt increase of subsidence that changed the alluvial architecture. As an alternative to sequence stratigraphic nomenclature defined for strata controlled by shoreline movements, a scheme relating systems tracts and surfaces to changes in stratigraphic base level is proposed. Such a scheme is useful where correlations to shoreline strata are ambiguous or cannot be made, or where tectonics and climate are important controls.     

Glacially-crushed quartz grains in late Quaternary deposits in the Virunga Mountains,Rwanda -indicators of wind transport from the north?

Quartz sand grains in late Quaternary deposits of the Virunga Mountains, northwestern Rwanda, were found to contain glacial-crushing microtextures. Glacially-crushed subangular grains generally lack sharp edges, and carry mainly low frequency, linear crushing features. Because there are no known tills in the Virunga Volcanoes (and because quartz is rare in volcanic terrain), it is likely the grains were delivered by aeolian transport from the Ruwenzori Massif, -150 km to the north. All the grains studied are consistent with crushing under low shear stress, and over short transport distances, in alpine glaciers. An increase in the percentage of glacially-crushed quartz from Holocene to Pleistocene beds likely reflects on the increased strength of the paleowind system (trade winds) during the last glacial maximum. Alternatively, it could reflect on the increased source area for glacially-crushed grains resulting from an increase in the extent of the Afroalpine belt during the last glaciation.     

Palaeomagnetism of the Moberly formation, northern Missouri, confirms a regional magnetic datum within the pre-Illinoian glacial sequence of the midcontinental USA

The Moberly formation of northern Missouri, USA includes glacigenic sediment deposited during the second major pre-Illinoian glaciation and is overlain by three younger normal-polarity tills. The Moberly (mostly till) preserves two different magnetic remanences. A detrital remanent magnetization has reversed polarity with shallow (-30 to-40°) inclinations. The shallow inclination is regionally persistent and spans different facies, including those not prone to large inclination error. A secondary overprint of normal polarity is associated with a thin oxidized zone and weakly developed paleosol in the upper portion of the till. This chemical remanent magnetization is distinguished by high coercivities typical of authigenic ferromagnetic minerals and by scattered remanence vectors upon stepwise demagnetization. The secondary normal remanence was likely acquired during a brief interglacial period between deposition of the Moberly formation and the next glaciation. The short interglacial and the shallow inclinations indicate that the glaciation which deposited the Moberly occurred shortly before a major polarity change from reverse to normal, probably the Brunhes-Matuyama reversal.     

Younger Dryas-age readvance of Laurentide ice into the Champlain Sea

Occurrences of Balanus hameri-bearing diamicts described in this paper and pertinent ( Balanus plates and pelecypods shells) ¹⁴C dates suggest that there was glacial activity in the Champlain Sea basin between 11,000 BP and 10,400 BP and that this activity can be ascribed to a climatic cooling episode correlative with the Younger Dryas of the late-glacial sequence of northeastern Europe.     

WATER MANAGEMENT—A GENERAL REPORT

Abstract

This analysis was undertaken to develop appropriate extreme flood design criteria for a nuclear power plant at Halileh, near Bushehr, Iran, adjacent to the Persian Gulf. Graphical relationships presented provide a convenient means of estimating the probable maximum precipitation and the 2- to 100-year return period rainfall events with durations from 5 min to 24 h. The relationships may be applied for drainage areas up to 25 km². Probable maximum precipitation and 2- to 100-year return period rainfall events were estimated. Precipitation depth-duration relationships were derived.