首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Abstract

Fort George was built between 1748 and 1760 at Ardersier Point on the Moray Firth. Extensive contemporary documentation of the fort's construction survives in the archives of the Board of Ordnance. This paper describes archaeological fieldwork carried out during conservation works between 1990 and 2005. Excavation was undertaken on the East Front, the Point Battery at the western extremity, and the North and South Casemates. Work was also undertaken at the Men's Latrine and at the Pier. Together with detailed analysis of documentary sources, fieldwork has enhanced understanding of methods and priorities for defence procurement during the mid-18th century.  相似文献   

2.
A robust debate among coastal geomorphologists as to the processes by which beach‐ridge plains around Australia have formed was initiated by a former President of the Institute of Australian Geographers. This review gives special consideration to the work of Jack L. Davies, whose academic contributions to coastal geomorphology in Australia have not always been appropriately acknowledged when explaining how similar plains have evolved elsewhere in the world. Davies recognised that relatively steep storm waves caused erosion (cut) on beaches, whereas less steep long‐period swell waves returned sand (fill). He considered the beach berm to be the nucleus on which a beach ridge formed, which could subsequently develop into a foredune, in contrast to cobble ridges that were deposited during storms. Offshore conditions regulate supply of sand to the shoreline, partly through effects on wave refraction, with higher rates of supply where the nearshore is shallow. It was apparent to Davies that the elevation of successive ridges might, but not necessarily, provide evidence of past changes of sea level, despite adornment by variable amounts of windblown dune sand. Morphodynamic understanding of long‐term coastal evolution, based on radiocarbon dating chronologies, has demonstrated that Australian coastal plains formed over the past ~6,000 years when sea level has been close to its present level, in contrast to several documented locations in the northern hemisphere where the sea has been rising for the past few millennia. Particularly insightful were observations by Davies that ridge formation could be influenced by a range of factors including changes in sea level, storminess, or sediment supply. These factors acting singly or in combination seem likely to change in the future. Understanding such responses remains a high priority and can be addressed by new technologies, such as light detection and ranging, optically stimulated luminescence dating, ground‐penetrating radar, and computer simulation.  相似文献   

3.
The Sandbanks of Webb Bay, Labrador owe their origin to ice marginal conditions during the last stages of deglaciation of this section of the Labrador coast. Several phases in their evolution are recognized. Phase 1 was characterized by disintegration of the remnants of Webb Bay and Ado's Brook valley ice masses into separate local bodies with ice marginal runoff in an eastern direction. During Phase 2 the first and highest ice-dammed lake formed. Eastward ice marginal flow continued into Phase 3, when a large system of kame terraces (altitude 360 feet) formed beside the receding Webb Bay Ice. They led to new and lower ice marginal lakes in the eastern part of the Sandbanks. Phase 4 was dominated by the construction of a more extensive system of kame terraces almost 100 feet lower than those formed in Phase 3. Locally, minor moraines helped to direct runoff and control development of these newer kame terraces. In Phase 5, meltwater from the ice and runoff from the deglaciated highlands filled a large marginal lake (altitude 230 feet), which may have contributed to subglacial drainage down Port Manvers Run. Phase 6, the last of the glacial conditions associated with formation of the Sandbanks, was introduced by withdrawal of ice far enough so that the eustatically rising sea level was able to reach part of the Sandbanks. A terrace at 135 feet above sea level is believed to be the local upper marine limit. Stagnant ice still covered the floor of Hummock Valley at the western end of the Sandbanks at this time. Subsequently isostatic adjustment has lifted the last glacio-fluvial and some of the glacio-marine features above sea level.  相似文献   

4.
ABSTRACT

Medial moraines deposited by former glaciers and ice sheets are rare in Scotland. The most prominent example is the Sgriob na Caillich moraine, which consists of two to four parallel belts of angular quartzite boulders that extend northwestwards for over 3.5?km from the SW flank of Beinn an Oir on the Isle of Jura. The boulder belts extend to within 300?m of the present coastline, where they are truncated by a low bluff and raised marine terrace. The source of the moraine coincides with bedrock gullies and cliffs that represent the scars of former rock-slope failure(s), indicating that the moraine debris was sourced by one or more rockfalls or rockslides onto the ice surface after Beinn an Oir had emerged from the thinning ice cover as a nunatak. Exposure dating of boulders on the moraine indicate that it formed at 16.6?±?0.8?ka, consistent with the timing of ice-sheet retreat in this sector. The alignment of the moraine indicates ice-margin retreat to the SE; as regional ice-sheet retreat across the adjacent offshore shelf was to the NE, this anomaly implies that a residual icefield became stranded on Jura during ice-sheet retreat.  相似文献   

5.
Observations are presented of a newly deposited snow-push ridge superimposed on a Holocene moraine in Coire an Lochain in the Cairngorm Mountains. The ridge formed when a sliding snow slab was thrust up the proximal slope of the moraine, entraining till gravel and redepositing it on the moraine crest. The process was a late-stage event during the complex wastage of a large snowfield resting on a rock slab, involving basal sliding, avalanching and melting. Snow-push landforms appear to be rare in Scotland. Nevertheless, these observations suggest that fresh material may be added to relict moraine crests in the present-day climate, with implications for exposure-age dating of moraines. However, in this case the addition of debris by snow push to a late Holocene moraine crest does not affect the interpretation of moraine age.  相似文献   

6.
In an area of 400 sq km in the south east Grampians including Glen Esk, Glen Clova and part of Glen Muick the limits of former corrie glaciers, valley glaciers and a plateau ice‐cap with associated outlet glaciers have been mapped. The limits of the former corrie and valley glaciers are often clearly defined by end moraines, boulder‐strewn ground, the down‐valley termination of hummocky moraines and/or the limits of meltwater channel systems, while in suitable locations outwash terraces usually occur. The glaciers are considered to have formed during the Loch Lomond (pollen zone III) Readvance, when new glaciers developed in upland sources following complete ice‐sheet decay. The readvance was accompanied in granite areas by the formation of large solifluction lobes, these lobes being found only outside the mapped ice limits. The interpretations presented are not in accord with those recently given by D. E. Sugden for the western Cairngorms.  相似文献   

7.
Due to the direct relationship between their function and ancient sea levels, Roman fish tanks and fish traps are excellent indicators for sea level changes through time. For this study, eleven submerged systems of fish tanks were investigated along the rocky southern coast of the gulf of Matala, Crete. Seven of them are still in a good state of preservation and thus underwent detailed survey and documentation. The measurements of their recent submersion, the determination of the way they operated, as well as their correlation with coastal landforms indicative of an older sea level, permit the identification of a mean Roman sea level at the SW coast of central Crete 1.25 m below the present one. According to historical evidence, the submersion of the SW coasts of the central part of Crete must have been occurred between 1415 and 1865 during a paroxysmal tectonic event and is probably related with the strong earthquake of 1604.  相似文献   

8.
Whitianga Harbour on the Coromandel Peninsula, North Island, New Zealand is fronted by a broad sandy barrier composed of linear beach ridges. The barrier developed through a process of rollover as sea level rose in the early Holocene with shelly sandy sediment washed inland over estuarine muds. These overwash deposits are present to 3 m below sea level in the back barrier area. Once sea level stabilised and barrier rollover had ceased the barrier continued to prograde in a series of beach ridges. The back barrier area is characterised by estuarine muds, overlain by splay and overwash deposits that are reworked by fluvial and tidal channels. The initial flooding of the estuary occurred at around 7350–7225 years cal BP, reaching modern levels by 6894–6729 years cal BP at the earliest. Infill was rapid as evidenced by estuarine species (crustaceans and bivalves) preserved in life position. From ~6000 years BP to present, the estuary is characterised by tidal and fluvial reworking, suggesting that modern sediment inputs are bypassing the estuary.  相似文献   

9.
Abstract

Reconstructions of the late Quaternary paleogeography of Greece and the Aegean show that at 18,000 years B.P. the northern Aegean and northern Adriatic formed large coastal plains traversed by many rivers. Broad plains also existed off the coast of Elis and the present Gulf of Korinth, and along the Anatolian coast. Many islands, such as Kerkira, Euboea, and the northern Sporadhes, were connected with the mainland, and most of the Cycladic islands were joined together in a Cycladic semi-peninsula. The post-glacial rise of sea level beginning ca. 15,000 B.P. restored around 9,000 B.P. the coastal geography to approximately its present configuration. The late Quaternary paleogeography and its subsequent changes have many archeological implications that are worth serious consideration. The well-watered northern coastal plains may have furnished subsistence for a plains population quite independent of the resources of the northern mountain regions, and they constituted easy access to the Greek peninsula from the NE and NW. Loss of coastal plain land during the post-glacial rise of sea level drastically changed the resource base in many areas. The island of Melos, known source of obsidian for toolmaking since at least 10,000 B.P., may have been discovered considerably earlier when access to the island was largely over land.  相似文献   

10.
Abstract

California's Channel Islands currently have around 150,000 breeding seals and sea lions (pinnipeds). Driven to near extinction by 20th-century exploitation, many pinniped populations have recovered dramatically under federal and state management and continue to expand in number and distribution. Some of these pinniped populations are damaging or destroying coastal archaeological sites as they establish new breeding and haul-out areas—places occupied between periods of foraging activity—on upland landforms. We use archaeological excavations from a prehistoric village on San Miguel Island to illustrate the adverse effects pinnipeds can have on archaeological sites. Estimates based on excavations at Otter Point suggest that in one year nearly 10,000 kg of shellfish remains, 840,000 animal bones, and 1700 formal artifacts were lost to erosion caused by the activities of seals and sea lions. Our study documents potential conflicts between natural and cultural resource management suggesting the need for collaborative efforts between archaeologists and biologists to balance the conservation of both resources.  相似文献   

11.
Quaternary stratigraphy and sea level changes have been extensively investigated in many areas of the Mediterranean. However, numerical dating of coastal deposits and the associated paleoenvironmental information are limited for the coasts of Cyprus, principally based on radiometric and radiation-exposure geochronological techniques on fossils which bear a range of limitations and uncertainties. As such, optically stimulated luminescence (OSL) dating techniques are deemed to be the most suitable in direct dating of the coastal sediments of Cyprus. In the southeastern Cyprus, coastal dunes (aeolianites) now forming elongated ridges appear as morphological features running parallel to the current shoreline presenting an indicator of sea level and climate changes of great paleoenvironmental significance. We present our first chronological results for the exposed aeolianites and underlying littoral deposits formed along the southeastern coastal Cyprus ranging from 78.4 ± 9.9 to 56.2 ± 7.4 ka. The post-infrared–infrared stimulated luminescence (pIR-IRSL) revealed that dune formation took place during the marine isotope stages (MISs) 3, 4, and possibly 5a. Late Holocene reworking is proposed for a distinctively isolated dune with an age of ~1.3 ka ago. This study also showed that pIR-IRSL dating of feldspars may be a reliable alternative to quartz OSL dating when the quartz luminescence characteristics are unsuitable.  相似文献   

12.
Abstract

During several expeditions to the Antarctic Peninsula and the neighbouring islands, samples were collected from different sediments which contained datable materials or which were datable with new techniques. Thus it became possible to develop, together with our geomorphic field data, some new ideas on relief development at the rim of the Antarctic continent as well as on the glacial history of the area studied.

Planation surfaces in this area seem to be fairly old. For example, the prominent marine erosion surface on Fildes Peninsula, 35–45 m above mean sea level, is probably older than 85 000 years – older than the last interglacial period and the penultimate glaciation. All Holocene beaches, which are situated between 20 m and the present coastline, were formed during the last 6000 years.

Before 6000 BP the islands were still completely glaciated. The breakdown of the ice cover to nearly the present extent must have been extremely abrupt, taking no more than 1000 years (6000 to 5000 BP). Between 3000 and 1000 BP there were at least two re-advances. These advances were restricted to the prominent outlet glaciers, which followed pre-existing valleys.  相似文献   

13.
Abstract

Desert landscapes are the least understood among terrain types of the Earth. The dearth of basic information on arid landforms has resulted in the misconception that the desert is man-made and that, therefore, we can 'fix it'. Scientific evidence indicates that deserts are part of the natural features of both Earth and Mars. They form as a result of the lack or scarcity of rain, which may be cyclical. The basic layout of today's arid terrain appears to have formed during humid periods in the geological past. Understanding of such features and those caused by wind erosion and deposition is essential to the development of deserts and semiarid lands for the benefit of mankind. Images obtained by spacecraft provide a new tool that is very useful in this regard, particularly in the location of groundwater resources to be used at times of cyclical droughts.  相似文献   

14.
Investigation of shallow‐marine environments for submerged prehistoric archaeology can be hampered in many localities by extensive bedrock exposure and thus limited preservation potential. Using the concept of ‘seamless archaeology’ where land‐based archaeology is integrated across the intertidal zone through to the offshore, a multi‐disciplinary approach is essential. This approach taken in the Bay of Firth, Orkney uses geophysics, historical archive and ethno‐archaeology, coastal geomorphology, palaeo‐environmental analyses and sea‐level science, and allows a clearer understanding of the landscape in which prehistoric settlers lived. While acknowledging the limitations of the preserved environment, we are successful in identifying areas of archaeological potential on the sea‐bed for both upstanding structural elements as well as sediment preservation that contains evidence for human occupation. This has wider implications beyond Orkney's World Heritage sites to provide a blueprint for similar studies elsewhere in the coastal zone. © 2012 The Authors  相似文献   

15.
The elevation and age of surveyed shorelines in St Jonsfjorden, western Spitsbergen, provide a chronology for Late Weichselian deglaciation and a proxy for former ice thickness. Support is provided for previous reports of two sets of shorelines on NW Spitsbergen, the oldest (at 60 m in St Jonsfjorden) dating to a pre‐late Weichselian glaciation and the youngest documenting postglacial rebound. The remarkable survival of the older shorelines suggests that a large area of NW Spitsbergen was either covered by protective, cold‐based ice or was subject to only local glaciation during the late Weichselian even though glacier ice extended to the shelf edge in the Isfjorden Trough. A marine limit of 46 m at the mouth of St Jonsfjorden is compatible with the regional late Weichselian marine limit (LWML) dated to ~13 ka BP. A partial relative sea level curve and equidistant shoreline diagram are produced for St Jonsfjorden and used in conjunction with relative sea level curves based on data from previous studies to produce an isobase map for 9 ka BP. The curves indicate that western sites were subject to initial slow emergence followed by rapid emergence between 10 ka and 8.2 ka BP, trends characteristic of areas affected by a full glacial sea or at least subject to early break up of a thin or discontinuous glacier ice cover. A step in the 9 ka BP shoreline long profile over the western end of the peninsula separating Isfjorden and van Mijenfjorden suggests that Holocene neotectonics may have produced anomalously high rebound rates in that area.  相似文献   

16.
Abstract

Archaeological surveys and prehistoric settlement patterns are best interpreted when placed on a geomorphic map that defines the distribution and age of physical landforms. Survey data can thus be used to address questions of archaeological site visibility and synchronic and diachronic site patterning on the Gila River Indian Reservation, Arizona. A chronological series of alluvial and eolian landforms are defined on the reservation. The age of the landforms and underlying sediments has affected the preservation and visibility of the archaeological record. Further, late prehistoric Hohokam settlements (A.D. 700–1500) and their associated agricultural lands show a clear landform zonation and that the intensity of use of these landforms has changed over time.  相似文献   

17.
Abstract

Since the creation of the European Community, the Gaullist movement has never been united over the question of European integration. De Gaulle’s intergovernmental vision of the European project has largely been the dominant discourse. At times however, this narrative has been questioned—on the one hand by more supranational notions of European integration; and on the other by a more pro-sovereignty Eurosceptic discourse. Subsequently, in its various modern-day guises the Gaullist movement has faced a series of major internal divisions with regard to its position on ‘Europe’. This uncertainty has also manifested itself at the highest level as demonstrated by the changing discourse advocated by former French presidents Jacques Chirac and Nicolas Sarkozy. This paper analyses the internal tensions over the European issue within the Gaullist movement at elite level. It determines that despite Chirac’s and Sarkozy’s attempts to unite the party throughout their presidencies the Gaullist movement is far from having moved towards a united European stance. Accordingly, the authors identify that over the past three decades, it is possible to identify three distinct, and at times conflicting, Gaullist stances on European integration with which the party’s elites have vacillated, namely Euro-Federalism, Euro-Pragmatism and Euro-Populism.  相似文献   

18.
Abstract

In August 2001, a programme of survey and trial excavation was carried out on the island of Inchkeith in the Firth of Forth in Scotland. The work was carried out as part of the first series of the BBC TV series Two Men in a Trench, and examined the WWII defences, together with some of the Victorian defences and a midden that probably dates to the 16th century.  相似文献   

19.
After the last Holocene sea level rise (about 6900 BP), the Gulf of Tartessos extended over the south-western area of the nowadays Guadalquivir Valley (Spain). With the development of some depositional littoral landforms and the progressive infill, the system evolved towards an inland lagoon. The first political system in the area emerged and collapsed from the fourth to the second millennium BC. Around the first millennium BC the culture of Tartessos flourished in this area under the Phoenician influence, but it vanished by the sixth century BC. The quest of its lost capital, the city of Tartessos, has been one of the most exciting archaeological enterprises in the past century. The former coastline and the bathymetry of the gulf can be reasonably reconstructed from geo-archaeological studies, and it can be used for the numerical modeling of tide and tsunami propagation in this water body. Models, with a spatial resolution of 30 s of arc, are based on the 2D non-linear hydrodynamic equations and have been previously validated under nowadays conditions. Computed tidal elevations and currents can provide some insight on the ancient trades for ship traffic and fisheries. The simulation of tsunami propagation, like the catastrophic one of 1755, allows estimating their potential hazardous effects on ancient coastal cities.  相似文献   

20.
A combination of reconstruction of the former coastline and field survey of previously unrecorded sites provides the basis for the study of the maritime landscape and maritime activities around Portrush on the north coast of Ireland during the Mesolithic period. Movements in relative sea‐level and geological events indicate significant change in environment and availability of resources, particularly flint, for the coastal community. Evidence suggests that most Early Mesolithic material, deposited close to the then shoreline, is presently under water. Remnants of the Late Mesolithic are fast disappearing as coastal erosion continues. © 2010 The Author  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号