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Geosciences, Volume 2, Issue 4 (December 2012), Pages 178-307

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Research

Open AccessArticle Recognizing Vertical and Lateral Variability in Terrestrial Landscapes: A Case Study from the Paleosols of the Late Pennsylvanian Casselman Formation (Conemaugh Group) Southeast Ohio, USA
Geosciences 2012, 2(4), 178-202; doi:10.3390/geosciences2040178
Received: 6 August 2012 / Revised: 5 September 2012 / Accepted: 18 September 2012 / Published: 26 September 2012
Cited by 2 | PDF Full-text (5117 KB) | HTML Full-text | XML Full-text
Abstract
The Upper Pennsylvanian Casselman Formation of southeastern Ohio contains four distinct paleosol types that formed in alluvial systems within the distal Appalachian foreland basin. The properties of these paleosols as well as their small-scale lateral and vertical variations were studied to interpret [...] Read more.
The Upper Pennsylvanian Casselman Formation of southeastern Ohio contains four distinct paleosol types that formed in alluvial systems within the distal Appalachian foreland basin. The properties of these paleosols as well as their small-scale lateral and vertical variations were studied to interpret the paleoenvironmental and paleoecological conditions within the alluvial settings in which they formed. The ichnofossils and pedogenic features preserved within the paleosols of the Casselman Formation record the local climactic, hydrologic, biotic, and topographic changes that occurred in the region during the Late Pennsylvanian. The four paleosols types of the Casselman Formation are interpreted as Alfisols (Type A, Type D), Vertisols (Type B), and Inceptisols (Type D). The four paleosol types indicate different degrees of changes in local moisture regimes including water table fluctuations due to seasonal precipitation and flooding events. The assemblages of ichnofossils within the paleosol types were produced by both soil arthropods and a diverse array of plants that formed part of the different soil ecosystems present within the alluvial environment. Although regional-scale studies are important for understanding the Late Pennsylvanian world, small-scale studies are also necessary to fully understand the local pedogenic, paleoenvironmental, and paleoecologic consequences of global scale changes in paleoclimate and paleogeography. Full article
Open AccessArticle Remote Sensing and Geographic Information Systems (GIS) Contribution to the Inventory of Infrastructure Susceptible to Earthquake and Flooding Hazards in North-Eastern Greece
Geosciences 2012, 2(4), 203-220; doi:10.3390/geosciences2040203
Received: 1 August 2012 / Revised: 12 September 2012 / Accepted: 17 September 2012 / Published: 27 September 2012
Cited by 2 | PDF Full-text (9814 KB) | HTML Full-text | XML Full-text
Abstract
For civil protection reasons there is a strong need to improve the inventory of areas that are more vulnerable to earthquake ground motions or to earthquake-related secondary effects, such as landslides, liquefaction or soil amplifications. The use of remote sensing and Geographic [...] Read more.
For civil protection reasons there is a strong need to improve the inventory of areas that are more vulnerable to earthquake ground motions or to earthquake-related secondary effects, such as landslides, liquefaction or soil amplifications. The use of remote sensing and Geographic Information Systems (GIS) methods along with the related geo-databases can assist local and national authorities to be better prepared and organized. Remote sensing and GIS techniques are investigated in north-eastern Greece in order to contribute to the systematic, standardized inventory of those areas that are more susceptible to earthquake ground motions, to earthquake-related secondary effects and to tsunami-waves. Knowing areas with aggregated occurrence of causal (“negative”) factors influencing earthquake shock and, thus, the damage intensity, this knowledge can be integrated into disaster preparedness and mitigation measurements. The evaluation of satellite imageries, digital topographic data and open source geodata contributes to the acquisition of the specific tectonic, geologic and geomorphologic settings influencing local site conditions in an area and, thus, estimate possible damage to be suffered. Full article
(This article belongs to the Special Issue Geoscience of the Built Environment)
Open AccessArticle Ocean Acidification and the End-Permian Mass Extinction: To What Extent does Evidence Support Hypothesis?
Geosciences 2012, 2(4), 221-234; doi:10.3390/geosciences2040221
Received: 21 July 2012 / Revised: 16 August 2012 / Accepted: 18 September 2012 / Published: 28 September 2012
Cited by 5 | PDF Full-text (4927 KB) | HTML Full-text | XML Full-text
Abstract
Ocean acidification in modern oceans is linked to rapid increase in atmospheric CO2, raising concern about marine diversity, food security and ecosystem services. Proxy evidence for acidification during past crises may help predict future change, but three issues limit confidence [...] Read more.
Ocean acidification in modern oceans is linked to rapid increase in atmospheric CO2, raising concern about marine diversity, food security and ecosystem services. Proxy evidence for acidification during past crises may help predict future change, but three issues limit confidence of comparisons between modern and ancient ocean acidification, illustrated from the end-Permian extinction, 252 million years ago: (1) problems with evidence for ocean acidification preserved in sedimentary rocks, where proposed marine dissolution surfaces may be subaerial. Sedimentary evidence that the extinction was partly due to ocean acidification is therefore inconclusive; (2) Fossils of marine animals potentially affected by ocean acidification are imperfect records of past conditions; selective extinction of hypercalcifying organisms is uncertain evidence for acidification; (3) The current high rates of acidification may not reflect past rates, which cannot be measured directly, and whose temporal resolution decreases in older rocks. Thus large increases in CO2 in the past may have occurred over a long enough time to have allowed assimilation into the oceans, and acidification may not have stressed ocean biota to the present extent. Although we acknowledge the very likely occurrence of past ocean acidification, obtaining support presents a continuing challenge for the Earth science community. Full article
(This article belongs to the Special Issue Paleontology and Geo/Biological Evolution)
Figures

Open AccessArticle Oxygen-Dependent Morphogenesis of Modern Clumped Photosynthetic Mats and Implications for the Archean Stromatolite Record
Geosciences 2012, 2(4), 235-259; doi:10.3390/geosciences2040235
Received: 2 August 2012 / Accepted: 25 September 2012 / Published: 11 October 2012
Cited by 9 | PDF Full-text (3034 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Some modern filamentous oxygenic photosynthetic bacteria (cyanobacteria) form macroscopic tufts, laminated cones and ridges that are very similar to some Archean and Proterozoic stromatolites. However, it remains unclear whether microbes that constructed Archean clumps, tufts, cones and ridges also produced oxygen. Here, [...] Read more.
Some modern filamentous oxygenic photosynthetic bacteria (cyanobacteria) form macroscopic tufts, laminated cones and ridges that are very similar to some Archean and Proterozoic stromatolites. However, it remains unclear whether microbes that constructed Archean clumps, tufts, cones and ridges also produced oxygen. Here, we address this question by examining the physiology of cyanobacterial clumps, aggregates ~0.5 mm in diameter that initiate the growth of modern mm- and cm-scale cones. Clumps contain more particulate organic carbon in the form of denser, bowed and bent cyanobacterial filaments, abandoned sheaths and non-cyanobacterial cells relative to the surrounding areas. Increasing concentrations of oxygen in the solution enhance the bending of filaments and the persistence of clumps by reducing the lateral migration of filaments away from clumps. Clumped mats in oxic media also release less glycolate, a soluble photorespiration product, and retain a larger pool of carbon in the mat. Clumping thus benefits filamentous mat builders whose incorporation of inorganic carbon is sensitive to oxygen. The morphogenetic sequence of mm-scale clumps, reticulate ridges and conical stromatolites from the 2.7 Ga Tumbiana Formation likely records similar O2-dependent behaviors, preserving currently the oldest morphological signature of oxygenated environments on Early Earth. Full article
(This article belongs to the Special Issue Paleontology and Geo/Biological Evolution)
Open AccessArticle Examining Local Climate Variability in the Late Pennsylvanian Through Paleosols: An Example from the Lower Conemaugh Group of Southeastern Ohio, USA
Geosciences 2012, 2(4), 260-276; doi:10.3390/geosciences2040260
Received: 14 September 2012 / Revised: 18 October 2012 / Accepted: 29 October 2012 / Published: 1 November 2012
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Abstract
Three temporally close stratigraphic sections were excavated in Glenshaw Formation of Athens County, Ohio. The described units are Upper Pennsylvanian (Gzhelian, 305–302 Ma) and located in the distal portion of the Appalachian foreland basin. Mudstone units interpreted as paleosols were identified across [...] Read more.
Three temporally close stratigraphic sections were excavated in Glenshaw Formation of Athens County, Ohio. The described units are Upper Pennsylvanian (Gzhelian, 305–302 Ma) and located in the distal portion of the Appalachian foreland basin. Mudstone units interpreted as paleosols were identified across all three sections. Detailed field and micromorphological studies lead to the recognition of two separate paleosols within the profile. The profile consists of a composite paleosol composed of two cumulative paleosols. The lower paleosol is interpreted as a calcic Vertisol which formed in a seasonally dry environment whereas the upper paleosol is interpreted as a gleyed Inceptisol which formed in a seasonally wet environment. The change in paleosol types is the result of increased precipitation which led to saturation of the soil and surface ponding. Pedogenic carbonate nodules are a common feature throughout the entire profile as are stress cutans. A coalesced carbonate horizon (Bk) was observed approximate 120 cm from the top of the profile in all three sections. This carbonate horizon formed in the Vertisol and later served as a barrier which limited the downward movement of surface water. This limited the gleization of the bottom portion of the overprinted Vertisol resulting in a diffuse boundary with the overlying Inceptisol and producing a composite paleosol. Full article
Open AccessArticle A Site-Specific Index Based on Weathering Forms Visible in Central Oxford, UK
Geosciences 2012, 2(4), 277-297; doi:10.3390/geosciences2040277
Received: 15 September 2012 / Revised: 1 November 2012 / Accepted: 6 November 2012 / Published: 12 November 2012
Cited by 6 | PDF Full-text (8231 KB) | HTML Full-text | XML Full-text
Abstract
The authenticity of much of the stone-work along Queen’s Lane in central Oxford, UK presented an opportunity to produce a photographic survey from which a weathering index could be established. This represents a site-specific approach to devising a weathering form. Because it [...] Read more.
The authenticity of much of the stone-work along Queen’s Lane in central Oxford, UK presented an opportunity to produce a photographic survey from which a weathering index could be established. This represents a site-specific approach to devising a weathering form. Because it is photo-based, weathering forms are visible for comparison and classification purposes across disciplines. Limestone pertaining to building ashlar and plinths along this roadway, which mainly belong to Queen’s College, St Edmund Hall, New College, and Hertford College, was classified according to this newly introduced weathering index, the size-extent (S-E) index, through consideration of type, size, extent, impact, and trigger. This size- (range) and extent-based classification system enables for the assessment of weathering forms of various types, including soiling and decay features as well as those potentially expected in the presence of vegetation and animals. Weathering forms of a range of sizes were present, with a slightly greater abundance of small types (mm-cm in the micro- to mesoscale) and more discrete types with a low extent. For this location in central Oxford, chemical weathering was found to be the predominant type of soiling and decay. Full article
(This article belongs to the Special Issue Geoscience of the Built Environment)
Open AccessArticle Hellenic Natural Zeolite as a Replacement of Sand in Mortar: Mineralogy Monitoring and Evaluation of Its Influence on Mechanical Properties
Geosciences 2012, 2(4), 298-307; doi:10.3390/geosciences2040298
Received: 9 October 2012 / Revised: 14 November 2012 / Accepted: 16 November 2012 / Published: 22 November 2012
Cited by 3 | PDF Full-text (550 KB) | HTML Full-text | XML Full-text
Abstract
HEU-type zeolite-rich volcaniclastic tuff (Hellenic natural zeolite) is used as a raw material for the production of lighter mortars. The addition of natural zeolite in mortar mixtures of sand and Portland cement leads to a decrease of up to 18.35% unit weight. [...] Read more.
HEU-type zeolite-rich volcaniclastic tuff (Hellenic natural zeolite) is used as a raw material for the production of lighter mortars. The addition of natural zeolite in mortar mixtures of sand and Portland cement leads to a decrease of up to 18.35% unit weight. The increase of the natural zeolite proportions increases the porosity and water absorption of the mortar and, at the same time, decreases the uniaxial compressive strength. These variations in the mortar’s mechanical properties are due to the addition of natural zeolite, which causes incomplete hydration of C2S (2CaO.SiO2) and retardation of the mortar’s hardening. Full article
(This article belongs to the Special Issue Geoscience of the Built Environment)

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