Sandstone Ridges Research Articles

Periglacial geomorphological evolution of the Fontainebleau Massif (France)

The Fontainebleau Sand contains tightly cemented sandstone lenses, which form spectacular elongated ridges that are up to 10 km long and 0.5 km wide. Denudation of the sandstone pans leads to a highly contrasted landscape, with sandstone ridges towering over sandy depressions. However, little is known about the erosion processes that have built up this landscape. Periglacial processes, including aeolian ones, appear to have been significant in the development of the massif's physiography. The topography of the massif has played an important role in controlling the aeolian processes. The upwind westerly front face of the massif displays numerous deflation features, such as blowout hollows, high sandstone scarps with numerous overhangs and spectacular talus screen, and a wide uncovered sandstone plateaux. In the eastern downwind district the landforms are more subdued and the sandstone plateaux and their scarps are partly sanded up. Sand dunes have built up directly downwind from the westerly scarps. Further onto the plateaux, loess has been deposited in a relatively regular cover. Finally, in the low areas downwind from the plateaux, there are fine sand dune fields and loess covers. The layouts and arrangements inherited from the aeolian action partly command the present-day relief and the plant biodiversity. There are oak and beech groves on the aeolian calcareous sand deposits, birch and pine trees on the quartzose sand forming the upwind scarps, and wet peaty moors as well as dry moors with heather and birch on the uncovered sandstone plateaux. Thus, the landscape features inherited from the periglacial aeolian action contribute to the striking biodiversity of the Fontainebleau Massif.

Exhumed channel sandstone networks within fluvial fan deposits from the Oligo-Miocene Caspe Formation, South-east Ebro Basin (North-east Spain)

The Oligo-Miocene Caspe Formation corresponds to the middle fluvial facies of the wider Guadalope-Matarranya fluvial fan, located in the South-east Ebro foreland basin (North-east Spain). At the time of the Caspe Formation deposition, this sector of the Ebro basin underwent a very continuous, moderate sedimentation rate. Lithofacies comprise deposits from channellized and unchannellized flows. Channellized flow lithofacies form multi-storey ribbon-like sandstone bodies that crop out as extensive sandstone ridges belonging to exhumed channel networks. Width/thickness ratios of these channel-fill bodies average close to six. Sinuosity is usually low (most common values around 1·1), although it can be high locally (up to 2). Thicknesses range from a few metres to 15 m. Unchannellized flow lithofacies form tabular bodies that can be ascribed to overbank deposits (levees, crevasse splays and fine-grained floodplain deposits) and also to frontal lobes, although recognition of this last case requires exceptional outcrop conditions or geophysical subsurface studies. The unchannellized flow lithofacies proportion ranges from 75% to 97·8%. Methods applied to this study include detailed three-dimensional architectural analysis in addition to sedimentological analysis. The architecture is characterized by an intricate network of highly interconnected ribbon-like sandstone bodies. Such bodies are connected by three kinds of connections: convergences, divergences and cross-cuttings. Although the Caspe Formation lithofacies and architecture resemble anastomosed channels (low topographic gradient, high preservation potential, moderate aggradation rate, high lateral stability of the channels, dominance of the ribbon-like morphologies and high proportion of floodplain to channel-fill sediments), an unambiguous interpretation of the channel networks as anastomosed or single threaded cannot be established. Instead, the observed architecture could be considered as the product of the complex evolution of a fluvial fan segment, where different network morphologies could develop. A facies model for aggrading ephemeral fluvial systems in tectonically active, endorheic basins is proposed.

Analysis of the vegetation of the sandstone ridges (Ib land type) of the north-eastern parts of the Mapungubwe National Park, Limpopo Province, South Africa

The establishment of the Mapungubwe National Park has been an objective of several conservationists for many years. The ultimate objective is that this park should become a major component of a Transfrontier National Park shared by Botswana, Zimbabwe and South Africa. The aim of this study was to identify, classify and describe the plant communities present in the Ib land type of the park. Sampling was done by means of the Braun-Blanquet method. A total of 48 stratified random relevés were sampled in the Ib land type. All relevé data were imported into a TURBOVEG database, after which the numerical classification technique TWINSPAN was used as a first approximation. Subsequently, Braun-Blanquet procedures were used to refine data and a phytosociological table was constructed, using the visual editor, MEGATAB. Two plant communities and several subcommunities and variants were identified and described from the phytosociological table.

Ancient Tyre and its harbours: 5000 years of human-environment interactions

The exact location and evolution of Tyre's ancient harbour areas have been matters of scholarly conjecture since the 16th century. Here, we use geoscience techniques to precisely relocate the ancient northern harbour, the city's principal transport hub during antiquity, and reconstruct its geomorphological evolution (Marriner, N., Morhange, C., Boudagher-Fadel, M., Bourcier, M., Carbonel, P., 2005. Geoarchaeology of Tyre's ancient northern harbour, Phoenicia. Journal of Archaeological Science 32, 1302–1327.). While a natural anchorage is inferred during the Bronze Age, we expound the increasing weight of anthropogenic forcings from the Iron Age onwards, culminating in a technological apogee during the Byzantine period (Hohlfelder, R.L., 1997. Building harbours in the early Byzantine era: the persistence of Roman technology. Byzantinische Forschungen Internationale Zeitschrift für Byzantinistik 24, 367–389.). Using coastal stratigraphy and underwater archaeological data (El Amouri, M., El Helou, M., Marquet, M., Noureddine, I., Seco Alvarez, M., 2005. Mission d'expertise archéologique du port sud de Tyr, sud Liban: résultats preliminaries. Bulletin d'Archéologie et d'Architecture Libanaises, Hors-Série 2, 91–110; Frost, H., Recent observations on the submerged harbour works at Tyre. Bulletin du Musée de Beyrouth 24, 103–111; Noureddine, I., Helou, M., 2005. Underwater archaeological survey in the northern harbour at Tyre. Bulletin d'Archéologie et d'Architecture Libanaises, Hors-Série 2, 111–128) we demonstrate that Poidebard's (1939. Un grand port disparu, Tyr. Recherches aériennes et sous-marines, 1934–1936, Librairie Orientaliste Paul Geuthner, Paris) Egyptian harbour is in reality a drowned quarter of the ancient city. Informed hypotheses are proposed for a possible second anchorage at Tyre, and it is demonstrated that presently drowned portions of the sandstone ridge served as outer harbours during the Bronze and Iron Ages. Stratigraphic data in the vicinity of Tell Mashuk, Chawakir and Rachidiye are also presented and discussed.

The origin and glaciodynamic significance of sandstone ridge networks from the Hirnantian glaciation of the Djado Basin (Niger)

AbstractThe Djado Basin (Niger) was located beneath the inner part of the Late Ordovician ice sheet. The Felar‐Felar Formation consists mainly of glaciomarine deposits, associated with the major ice sheet recession within the glaciation, and is bounded by two glacial unconformities. Structures corresponding to sandstone ridges are found within the Felar‐Felar Formation. Sandstone ridges are several metres high, about 10 m wide and hundreds of metres long. These structures are organized in extensive anastomosed to sub‐polygonal networks. The association of sandstone ridge networks with the later glacial unconformity and with other glacial evidence suggests sub‐glacial conditions for their origin. Sandstone ridge sedimentological characteristics indicate that sandstone ridges result from the scouring of the Felar‐Felar Formation by sub‐glacial, turbulent and pressurized meltwater; then sub‐glacial cavities were infilled with sand derived from glacial abrasion. Sandstone ridge networks are comparable with tunnel channels and document unusual drainage structures of the inner part of the palaeo‐ice sheet.

Nutrient fluxes via litterfall and leaf litter decomposition vary across a gradient of soil nutrient supply in a lowland tropical rain forest

The extent to which plant communities are determined by resource availability is a central theme in ecosystem science, but patterns of small-scale variation in resource availability are poorly known. Studies of carbon (C) and nutrient cycling provide insights into factors limiting tree growth and forest productivity. To investigate rates of tropical forest litter production and decomposition in relation to nutrient availability and topography in the absence of confounding large-scale variation in climate and altitude we quantified nutrient fluxes via litterfall and leaf litter decomposition within three distinct floristic associations of tropical rain forest growing along a soil fertility gradient at the Sepilok Forest Reserve (SFR), Sabah, Malaysia. The quantity and nutrient content of small litter decreased along a gradient of soil nutrient availability from alluvial forest (most fertile) through sandstone forest to heath forest (least fertile). Temporal variation in litterfall was greatest in the sandstone forest, where the amount of litter was correlated negatively with rainfall in the previous month. Mass loss and N and P release were fastest from alluvial forest litter, and slowest from heath forest litter. All litter types decomposed most rapidly in the alluvial forest. Stand-level N and P use efficiencies (ratios of litter dry mass to nutrient content) were greatest for the heath forest followed by the sandstone ridge, sandstone valley and alluvial forests, respectively. We conclude that nutrient supply limits productivity most in the heath forest and least in the alluvial forest. Nutrient supply limited productivity in sandstone forest, especially on ridge and hill top sites where nutrient limitation may be exacerbated by reduced rates of litter decomposition during dry periods. The fluxes of N and P varied significantly between the different floristic communities at SFR and these differences may contribute to small-scale variation in species composition.

Peats Ridge: a sandy track, citrus farms, springs, valleys, dams and the politics of ground water

This piece of writing is part of an exploration of ‘the personal voice’ within a Doctorate of Creative Arts. I come to this degree with a background as a documentary filmmaker and oral historian and with recent experience in the curation of a social history exhibition. My dissertation is entitled "Braided Channels: Reflections on the 'Voice of Documentary' from a cross media and inter disciplinary perspective." The doctorate uses and examines several modes of address and definitions of communicative voice in order to extend our knowledge of how discourses can be delivered in a range of modes and media to engender a sense of veracity in the 'audience'. 
 
 In this essay I apply the quintessential documentary practice of metonymy to the medium of non- fiction writing, as a way to get to broader issues through individual example and personal experience. This paper then is a personal account of the uses of land and water on the Hawkesbury Sandstone ridge I lived on as a child and a consideration of how and why these patterns are shifting. This remembering has been motivated by current debates about water use, especially as it relates to bottled water coming from underground aquifers, alternatives to dam storage as the source of urban water supplies and the zoning of arable land adjacent to a growing city. I write in the spirit in which Katrina Proust of the ANU’s Centre for Resource and Environmental Studies notes that environmental history can be a valuable tool in planning for the sustainable future use of a resource. This style of ‘personal memoir meets environmental history’ has of course antecedents not only in documentary film but also in print based work. One example of such work is the collection Landscapes of the Heart: Narratives of Nature and Self, edited by Michael Aleksiuk and came out of the University of Alberta in 2002.

EDAPHIC SPECIALIZATION IN TROPICAL TREES: PHYSIOLOGICAL CORRELATES AND RESPONSES TO RECIPROCAL TRANSPLANTATION

Recent research has documented the importance of edaphic factors in de- termining the habitat associations of tree species in many tropical rain forests, but the underlying mechanisms for edaphic associations are unclear. At Sepilok Forest Reserve, Sabah, Malaysian Borneo, two main soil types derived from sandstone (ridges) and alluvium (valleys) differ in nutrient and water availability and are characterized by forests differing markedly in species composition, structure, and understory light availability. We use both survey and reciprocal transplants to examine physiological adaptations to differences in light, nutrient, and water availability between these soil types, and test for the importance of resource-use efficiency in determining edaphic specialization. Photosynthetic surveys for congeneric and confamilial pairs (one species per soil type) of edaphic specialists and for generalists common to both soil types show that species specializing on sandstone- derived soil had lower stomatal conductance at a given assimilation rate than those occurring on alluvial soil and also had greater instantaneous and integrated water-use efficiencies. Foliar dark respiration rates per unit photosynthesis were higher for sandstone ridge than alluvial lowland specialists. We suggest that these higher respiration rates are likely due to increases in photosynthetic enzyme concentrations to compensate for lower internal CO 2 concentrations resulting from increased stomatal closure. This is supported by lower pho- tosynthetic nitrogen-use efficiencies in the sandstone ridge specialists. Generalist species had lower water-use efficiencies than sandstone ridge specialists when growing on the drier, sandy ridgetops, but their nitrogen-use efficiencies did not differ from the species specialized to the more resource-rich alluvial valleys. We varied light environment and soil nutrient availability in a reciprocal transplant experiment involving two specialist species from each soil type. Edaphic specialist species, when grown on the soil type for which they were not specialized, were not capable of acclimatory shifts to achieve similar resource-use effi- ciencies as species specialized to that soil type. We conclude that divergent water-use strategies are an important mechanism underlying differences in edaphic associations and thus contributing to maintenance of high local tree species diversity in Bornean rain forests.

Funerary monuments and horse paintings: A preliminary report on the archaeology of a site in the tagant region of South East Mauritania – near Dhar Tichitt

A preliminary expedition to record new rock art sites in the Tagant region of the Mauritanian Sahara led to the (re)discovery of previously unpublished stone-walled habitation and what are thought to be rectangular funerary monuments, built substantially and in profusion along the length of the sandstone ridge, Guilemsi. Paintings in cliffs below the top of the ridge depict antelope, giraffe, cattle and mounted horses, as well as camels, handprints and Tifinagh inscriptions. This article reports the findings at this site, and looks briefly at the possible authorship of the paintings and the culture of stone-walling. Some of the horse paintings are ‘bi-triangular’, and bear a striking resemblance to those photographed by two of us (Coulson and Campbell) some 3,500 km further east in Chad.

The vegetation and flora of Platt Park, Southbury, Connecticut

Abstract Platt Park is a 43.3-hectare (107-acre) natural area situated in the Southwest Hills Eco-region of Southbury, in New Haven County, Connecticut. Characterized by Triassic sandstone and trap rock ridges, the area offers a diversity of habitats for plant life. This investigation of the vegetation types of Platt Park provides information relevant to the preservation and management of natural areas and critical habitats. Abundance data derived from 263 quadrats were analyzed by the computer program TWINSPAN, circumscribing seven cover types. These cover types are: the Wolffia spp. Cover Type, the Bromus inermis Cover Type, the Juniperus virginiana–Carex pensylvanica Cover Type, the Acer saccharum–Ostrya virginiana Cover Type, the A. saccharum–Berberis thunbergii–Lindera benzoin Cover Type, and the Tsuga canadensis Cover Type. A Shrubland–Woodland Cover Type was also represented, comprising mainly introduced and cultivated species. Each cover type and its corresponding habitat are discussed in the cont...

Late Pleistocene–Holocene marsh episodes along the Carmel coast, Israel

Late Pleistocene–Holocene sequences in the southern Carmel coastal plain of Israel were obtained from two cores, 12 and 16 m deep, at the western and eastern longitudinal troughs, separated by a north–south “kurkar” sandstone ridge. The core sequences unconformably overlie the kurkar and were analyzed using X-ray radiography, grain size analysis, organic matter and water content. The sequences include (a) Brown sandy clay units, indicating terrestrial conditions of aeolian sand and dust deposition and pedogenesis dated between 20,200–19,650 and 9540–9130 cal. yr BP (western trough) and to 14,000–13,000 and 7680–7510 cal. yr BP (eastern trough). They are related to gradual warming and wetter climate when the coastline was far to the west; (b) overlying dark silty clay sediments, indicating fresh to brackish, shallow-water marsh with organic and fossil-rich, hydromorphic mineral soil, which prevailed at the western trough until 9010–8640 cal. yr BP (900 yr) and dried while the coastline was 1 km to the west. The marsh deposits were exposed for 3600 yr and populated by Pre-Pottery Neolithic and Chalcolithic settlements before they were covered by marine-aeolian sand at 5100 yr. The Kabara marshes at the eastern trough are asynchronous with the western marshes and prevailed from 7680 to 7510 cal. yr BP until the present. The genesis of these marshes may be related to the transition to a drier climate, resulting in an increasing frequency of large floods, as indicated by the high sedimentation rate, as well as to sea-level rise and its effect on groundwater level.

‘NO KINGS, NO LORDS, NO SLAVES’: ETHNICITY AND RELIGION AMONG THE SEREER-SAFÈN OF WESTERN BAWOL, 1700–1914

The Sereer-Safèn occupied a defensible refuge zone in Western Bawol, where forests and sandstone ridges provided protection against Wolof monarchy. The Safèn were part of a larger ‘Sereer’ world that defined itself by opposition to Islam in the period from 1700 to 1914. This religious divide made the Sereer targets for enslavement by the Wolof, but Sereer religion was also linked to Safèn resistance to Islam, slavery and monarchy. Religion was interwoven with an ethnic boundary, which emphasized the incompatibility of Wolof and Sereer society. Safèn religion was centered on the village ‘shrine’ or xérém, which served as the focal point of ritual, justice, communication with the other world and defense.

Roman and Early Christian burial-complex at Leptiminus: first notice

Following the rescue excavation of part of the Roman cemetery and a Roman mausoleum (Site 200) on Dhahret Slama, on the SE edge of the ancient town of Leptiminus on the east coast of Tunisia, the continued pressure of modern building led to the discovery of a remarkably well preserved underground burial-complex, as well a considerable extension of the above-ground cemetery which we had previously sampled. The underground burial-complex includes a number of tunnels and chambers, undoubtedly part of a much larger area of catacombs. These underground structures are cut into the sandstone and limestone ridge known as the Formation Rejiche which runs along the coast.3 This geological formation was suitable for the cutting of Punic-type chambers, of which a number have been located on this side of Leptiminus, and for catacombs, of which other examples have been identified in the same region, at Sousse, Sullecthum, and probably Thapsus.The existence of underground structures became clear following enquiries made of local residents, who spoke of substructures and vaults beneath their houses. Residents noted that after heavy rains water vanished rapidly into the ground; we now realize that it disappears into the underground voids of built or carved structures.

Mapping geological features of the Jharia coalfield from Landsat-5 TM data

Abstract False Colour Composite 754, the principal component imagery and edge enhanced imagery of Landsat-5 TM data have been found useful in delineating the regional geological features, viz, the curvilinear coal bands and sandstone ridges, faults, fractures and dolerite dykes of the Jharia Coalfield of Bihar, India, covering an area of about 480 km2, where many parts are inaccessible to direct field mapping due to extensive opencast mining operations. The features, their occurrences and spatial dispositions, as deciphered from satellite data, are found to match significantly well with selective field maps.

Downstream Fining in a Network of Gravel‐Bedded Rivers

A network‐based routing model is used to determine how spatial variations in sediment supply influence rates of downstream fining in a small watershed in central Pennsylvania. Gravel of a specified size distribution and lithology is supplied to the network at zero‐order basins. Once in transport, the total sample weight and moments of the grain‐size distribution are modified according to empirical functions of transport distance. Contributions from each zero‐order basin are summed to determine the total population of sizes and lithologies at any location. In the study area, resistant quartz sandstone ridges supply sediment an order of magnitude larger than other lithologies. Because these ridges occur primarily in the basin headwaters, spatial variations in supply strongly influence rates of downstream fining. Model calculations indicate that spatial variations in supply alone account for over 80% of the decrease in mean grain size along the main channel.

Evolution of landforms in the southern part of Kuwait

Field investigation indicates the common existence of calcrete, dolocrete, gypcrete and silcrete in the southern part of Kuwait. Three different forms of topographic highs are identified: calcretic ridges, calcareous sandstone ridges and silcretic hills; these show a direct relationship to the pre-existing land topography. They also influence the development of present-day land morphology. Surface and near-surface duricrust in Kuwait developed during the Pleistocene and early Holocene. Genetically, the calcareous duricrust is related to pedogenic and groundwater action. Gypcrete and silcrete are formed after the development of calcrete. In a later stage, an arid environment prevailed and aeolian processes produced relief inversion. The role of duricrust in developing the landscape of Kuwait is well documented, but a comprehensive study to assess its role in the subsurface zones is required.

Geology of Deep-Water Sandstones in the Mississippi Stanley Shale at Cossatot Falls, Arkansas

ABSTRACT The Mississippian Stanley Shale crops out along the Cossatot River in the Ouachita Mountains of western Arkansas. Here, exposures of deep water sandstones and shales, on recently established public lands, present a rare, three-dimensional look at sandstones of the usually obscured Stanley. The Cossatot River State Park Natural Area includes eleven miles of rugged and spectacular wooded, sandstone ridges, and cascading water. Cossatot Falls, a series of class IV and V rapids, is developed on massive- to medium-bedded quartz sandstones on the north flank of an asymmetric, thrust-faulted anticline. In western Arkansas, the Stanley Shale is a 10,500-foot (3200 m) succession of deep water sandstone and shale. At Cossatot Falls, approximately 510 feet (155 m) of submarine fan channel sandstones, siltstones, and shales are exposed during low river stages. This section is composed primarily of sets of thinning-upward sandstone beds. With rare exceptions, the sandstones are turbidites, grading from massive, homogeneous, basal beds, upwards through festoon-crossbedded, thick beds, into rippled medium and thin beds. Sandstone sets are capped by thin shale and siltstone intervals. Regional, north-northwestward paleocurrent indicators are substantiated by abundant, generally east-west ripple crests, which are asymmetric to the north-northwest. Flute casts at the top of the sandstone sequence indicate an additional, east-west flow component. Based on regional, lithologic characteristics, the sandstones at Cossatot Falls appear to be within the Moyers Formation. The Moyers is the upper sandstone unit of the Stanley and is an oil and gas reservoir in the eastern Oklahoma Ouachitas.

Erosional Remnants and Adjacent Unconformities Along an Eolian-Marine Boundary of the Page Sandstone and Carmel Formation, Middle Jurassic, South-Central Utah

Sandstone ridges along the marine-eolian boundary of the Middle Jurassic Page Sandstone (eolian) with the lower Carmel Formation (restricted marine) in south-central Utah have been identified as erosional remnants consisting of strata of siliciclastic sabkha and eolian origin. The ridges lie within two distinct units of the Thousand Pockets Tongue of the Page. Two equally plausible models explain the genesis of these ridges. One model involves (1) early cementation of eolian and sabkha strata, (2) wind erosion leading to development of yardangs and unconformities, (3) yardang tilting due to evaporite dissolution, and (4) renewed deposition and burial. The alternative model explains ridge development through (1) subsidence, with tilting, of eolian and sabkha strata into evaporites due to loading from linear dunes, (2) evaporite dissolution and unconformity development, and (3) renewed deposition and burial. These models provide important clues about the nature of a missing part of the rock record. Reconstruction of units that were deposited but later eroded improves paleogeographic interpretation and here indicates that the Carmel paleoshoreline was considerably farther to the northwest than previously believed.

Palaeo‐yardangs: wind‐scoured desert landforms at the Permo‐Triassic unconformity

ABSTRACTIn Canyonlands National Park, south‐east Utah, at least 29 partly exhumed, aligned sandstone ridges trending generally N20°W occur at the upper unconformable surface of the Lower Permian (Leonardian) White Rim Sandstone. The ridges are at least 1·5 km long, 250 m wide and have up to 14 m of vertical relief (mean of 9 m). A thin lag of coarse sandstone that contains wind‐ripple laminae and granule ripples directly overlies the ridges. Angular blocks of sandstone within the lag and sand‐filled fissures immediately below the lag, within the ridges, attest to early cementation of the ridge‐forming material. SE‐dipping aeolian cross‐strata within the White Rim Sandstone and within the lag closely parallel the ridge trend. The ridges are interpreted as wind‐sculpted desert landforms (yardangs) that developed on the lithified upper surface of the White Rim Sandstone during an extended period of hyperaridity towards the end of the Permian.

Slope gradient and aspect effects on soils developed from sandstone in Pennsylvania

This study was initiated to determine the basic characteristics and genesis of soils on gentle to very steep slopes on two contrasting slope aspects. Two transects, a southwest (SW) and a northwest (NW) transect, were laid out on a sandstone ridge across the summit and steepest convex shoulder positions. The thickness of the O, A and E horizons was not related to slope gradient across soils on all slope gradients and aspects. This indicates that the present rate of soil formation is greater than erosion, the influence of erosion on steep slopes could be off-set by lateral movement of through-flow water above the B horizon, or the process of tree throw masks slope gradient effects. Solum depth, B horizon thickness, clay, Fe, and Al indexes decreased with increasing slope for both the NW and SW aspects. Organic carbon index decreased with increasing slope for the SW aspect. Decreases in effective precipitation over relatively larger surface areas at steep versus lower slope gradients, a longer influence of periglacial erosion following the Wisconsinan glacial advance, and present slow but significant soil creep could cause these differences in soil development across the slope. Solum depth, B horizon thickness, clay, Fe, and Al indexes showed a smaller decrease across the NW compared to the SW slope. Organic carbon did not decrease across the NW slope. The E horizon was also slightly thicker on the NW compared to the SW slope. These aspect differences were probably caused by less evaporation on “shaded” NW compared to “sunny” SW slopes which produce generally higher moisture levels and more effective eluviation and illuviation on the NW slope.