Inventory and Assessment of the Geomorphosites in Central Cyclades, Greece: The Case of Paros and Naxos Islands

The Cycladic landscape is characterized by landforms of natural beauty and rarity. Landforms resulting from differential erosion, weathering, tectonics, drainage network, sea level changes, and depositional processes can contribute to the development of geotourism in the area. This can be achieved by supporting conservation, protection and promotion of the geo-environment and nature, educating students, residents, and visitors. The aim of this work is to develop an inventory of the main geomorphosites of Paros and Naxos islands by assessing their scientific and additional values, using qualitative and quantitative criteria. Our results show that, besides the high scientific interest of the 75 geomorphosites, most are also characterized by a high ecological value and can potentially lead to a significant increase in the islands’ tourism. The results of this work aim at raise awareness on the geomorphological heritage of central Cyclades and provide a basis for their promotion, protection, and management.

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Saltmarshes in a time of change

Environmental Conservation ◽

10.1017/s0376892902000048 ◽

2002 ◽

Vol 29 (1) ◽

pp. 39-61 ◽

Cited By ~ 211

Author(s):

Paul Adam

Keyword(s):

Sea Level ◽

Native Species ◽

Rate Of Change ◽

Tidal Range ◽

Direct Result ◽

Sea Level Changes ◽

Ecological Value ◽

Relative Sea Level ◽

Global Sea Level ◽

The Tropics

Saltmarshes are a major, widely distributed, intertidal habitat. They are dynamic systems, responding to changing environmental conditions. For centuries, saltmarshes have been subject to modification or destruction because of human activity. In this review, the range of factors influencing the survival of saltmarshes is discussed. Of critical importance are changes in relative sea level and in tidal range. Relative sea level is affected by changes in absolute sea level, changes in land level and the capacity of saltmarshes to accumulate and retain sediment. Many saltmarshes are starved of sediment because of catchment modification and coastal engineering, or exposed to erosive forces, which may be of natural origin or reflect human interference. The geographical distribution of individual saltmarsh species reflects climate, so that global climatic change will be reflected by changes in distribution and abundance of species, although the rate of change in communities dominated by perennial plants is difficult to predict. Humans have the ability to create impacts on saltmarshes at a range of scales from individual sites to globally. Pressures on the environment created by the continued increase in the human population, particularly in developing tropical countries, and the likely consequences of the enhanced greenhouse effect on both temperature and sea level give rise to particular concerns. Given the concentration of population growth and development in the coastal zone, and the potential sensitivity of saltmarsh to change in sea level, it is timely to review the present state of saltmarshes and to assess the likelihood of changes in the near (25 years) future. By 2025, global sea level rise and warming will have impacts on saltmarshes. However, the most extensive changes are likely to be the direct result of human actions at local or regional scales. Despite increasing recognition of the ecological value of saltmarsh, major projects involving loss of saltmarshes but deemed to be in the public interest will be approved. Pressures are likely to be particularly severe in the tropics, where very little is known about saltmarshes. At the local scale the cumulative impacts of activities, which individually have minor effects, may be considerable. Managers of saltmarshes will be faced with difficult choices including questions as to whether traditional uses should be retained, whether invasive alien species or native species increasing in abundance should be controlled, whether planned retreat is an appropriate response to rising relative sea level or whether measures can be taken to reduce erosion. Decisions will need to take into account social and economic as well as ecological concerns.

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High-resolution Stratigraphy of Holocene Lagoon Terraces of Southern Brazil

Quaternary Research ◽

10.1016/j.yqres.2014.08.007 ◽

2015 ◽

Vol 83 (1) ◽

pp. 52-65 ◽

Cited By ~ 1

Author(s):

Natália B. dos Santos ◽

Ernesto L.C. Lavina ◽

Paulo S.G. Paim

Keyword(s):

High Resolution ◽

Sea Level ◽

Radiometric Dating ◽

Sea Level Changes ◽

Relative Sea Level ◽

Base Level ◽

Depositional Processes ◽

Close Relationship ◽

Northern Portion ◽

Depositional Architecture

AbstractThe northern portion of the coastal plain of the Rio Grande do Sul State (southernmost Brazil) comprises an outer sandy barrier that protects a complex lagoon system formed during the Holocene. The terraces of three different lagoons (Gentil, Malvas and Pinguela) formed along their margins record the depositional processes and the relative base level changes over the past 5000 yr. Therefore, our main objective was to characterize and quantify base level fluctuations from the study of these terraces, to correlate them to sea-level changes and to describe the depositional architecture related to the distinct sea-level stages (high-resolution sequence stratigraphy). Satellite images, topographic and GPR profiles, auger holes and radiometric dating were used. The main results indicate a close relationship between relative base level and relative sea-level changes, a stillstand period just after the last transgressive maximum (4840–4650 cal yr BP) and a subsequent overall relative sea-level fall of about 3 m. Both a normal (highstand systems tract) and a forced regression (falling-stage systems tract) controlled the geological record preserved in the terraces. The highstand (older terrace) is characterized by agradational bedding, whereas the falling stage comprises three progradational sets (terraces) bounded by erosive surfaces related to smaller-scale sea-level drops.

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Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

Brazilian Journal of Geology ◽

10.1590/2317-4889201620160066 ◽

2016 ◽

Vol 46 (2) ◽

pp. 301-328 ◽

Cited By ~ 14

Author(s):

Mario Vicente Caputo ◽

Emilio Alberto Amaral Soares

Keyword(s):

South America ◽

Atlantic Ocean ◽

Sea Level ◽

Late Miocene ◽

Middle Miocene ◽

Drainage System ◽

Sedimentary Basins ◽

Amazon River ◽

Drainage Network ◽

Sea Level Changes

ABSTRACT: The development of the transcontinental Amazon River System involved geological events in the Andes Chain; Vaupés, Purus and Gurupá arches; sedimentary basins of the region and sea level changes. The origin and age of this river have been discussed for decades, and many ideas have been proposed, including those pertaining to it having originated in the Holocene, Pleistocene, Pliocene, Late Miocene, or even earlier times. Under this context, the geology of the sedimentary basins of northern Brazil has been analyzed from the Mesozoic time on, and some clarifications are placed on its stratigraphy. Vaupés Arch, in Colombia, was uplifted together with the Andean Mountains in the Middle Miocene time. In the Cenozoic Era, the Purus Arch has not blocked this drainage system westward to marine basins of Western South America or eastward to the Atlantic Ocean. Also the Gurupá Arch remained high up to the end of Middle Miocene, directing this drainage system westward. With the late subsidence and breaching of the Gurupá Arch and a major fall in sea level, at the beginning of the Late Miocene, the Amazon River quickly opened its pathway to the west, from the Marajó Basin, through deep headward erosion, capturing a vast drainage network from cratonic and Andean areas, which had previously been diverted towards the Caribbean Sea. During this time, the large siliciclastic influx to the Amazon Mouth (Foz do Amazonas) Basin and its fan increased, due to erosion of large tracts of South America, linking the Amazon drainage network to that of the Marajó Basin. This extensive exposure originated the Late Miocene (Tortonian) unconformity, which marks the onset of the transcontinental Amazon River flowing into the Atlantic Ocean.

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Submarine Geomorphology of the Southwestern Sardinian Continental Shelf (Mediterranean Sea): Insights into the Last Glacial Maximum Sea-Level Changes and Related Environments

Water ◽

10.3390/w13020155 ◽

2021 ◽

Vol 13 (2) ◽

pp. 155

Author(s):

Giacomo Deiana ◽

Luciano Lecca ◽

Rita Teresa Melis ◽

Mauro Soldati ◽

Valentino Demurtas ◽

...

Keyword(s):

Continental Shelf ◽

Sea Level ◽

Last Glacial Maximum ◽

Glacial Maximum ◽

Sea Level Changes ◽

Side Scan Sonar ◽

Last Glacial ◽

Depositional Processes ◽

The Last Glacial Maximum ◽

The Last Glacial

During the lowstand sea-level phase of the Last Glacial Maximum (LGM), a large part of the current Mediterranean continental shelf emerged. Erosional and depositional processes shaped the coastal strips, while inland areas were affected by aeolian and fluvial processes. Evidence of both the lowstand phase and the subsequent phases of eustatic sea level rise can be observed on the continental shelf of Sardinia (Italy), including submerged palaeo-shorelines and landforms, and indicators of relict coastal palaeo-environments. This paper shows the results of a high-resolution survey on the continental shelf off San Pietro Island (southwestern Sardinia). Multisensor and multiscale data—obtained by means of seismic sparker, sub-bottom profiler chirp, multibeam, side scan sonar, diving, and uncrewed aerial vehicles—made it possible to reconstruct the morphological features shaped during the LGM at depths between 125 and 135 m. In particular, tectonic controlled palaeo-cliffs affected by landslides, the mouth of a deep palaeo-valley fossilized by marine sediments and a palaeo-lagoon containing a peri-littoral thanatocenosis (18,983 ± 268 cal BP) were detected. The Younger Dryas palaeo-shorelines were reconstructed, highlighted by a very well preserved beachrock. The coastal paleo-landscape with lagoon-barrier systems and retro-littoral dunes frequented by the Mesolithic populations was reconstructed.

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Tide-dominated deltas responding to high-frequency sea-level changes, Pre-Messinian Rifian Corridor, Morocco

Journal of Sedimentary Research ◽

10.2110/jsr.2020.010 ◽

2020 ◽

Vol 90 (11) ◽

pp. 1642-1666

Author(s):

Daan Beelen ◽

Lesli Wood ◽

Mohamed Najib Zaghloul ◽

Faouziya Haissen ◽

Michiel Arts ◽

...

Keyword(s):

Mediterranean Sea ◽

Sea Level ◽

Coarse Grained ◽

Tidal Range ◽

Sea Level Changes ◽

Cross Sectional ◽

Depositional Processes ◽

Wide Range ◽

The Mediterranean ◽

Sedimentary Fill

ABSTRACT The Rifian Corridor was an ancient sea strait that connected the Mediterranean Sea with the Atlantic Ocean during the Miocene. Key outcrop exposures of this corridor's sedimentary fill are exposed at the Ben Allou, El Adergha, and Driouate localities, in the Fez–Meknes region, Morocco. These display cyclic successions that formed immediately before the disappearance of the Rifian Corridor, and the associated isolation and desiccation of the Mediterranean Sea. Sedimentary cycles at Ben Allou consist of: facies 1, Organic-matter-bearing blue claystones; facies 2, gray marlstones intercalated with turbidites; and facies 3, yellow-brown, coarse-grained calcarenites. Based on their coarse grain size, presence of reactivation surfaces, bidirectional current structures, and mud drapes as well as microfossil, macrofossil and trace fossil assemblages, we interpret the calcarenites (facies 3) as prograding, strait-adjacent tide-dominated deltas transitioning from large subtidal compound dunes to intertidal sand sheets that are composed mostly of authigenic carbonate sediment. The two fine-grained facies were deposited in deeper prodelta (facies 2) and shelfal (facies 1) environments, as shown by our combined sedimentological and paleontological evidence. Cross-sectional channel geometries provide a means for reconstructing the delta's paleo–tidal range, suggesting that it was macrotidal, and likely amplified by the paleogeometry of the Southern Rifian Corridor, to at least 4.2 m. The cyclic succession of corridor fill exposed here likely is the result of three, roughly 70 m fluctuations of eustatic rise and subsequent fall, possibly linked to ∼ 100,000-year glacial–interglacial climate fluctuations. Broadly similar, contemporaneous sedimentary successions from the outcrop at El Adergha, 40 km east of Ben Allou, show that these sea-level variations affected a wide range of the Corridor, while rocks at the locality of Driouate, 9 km south of Ben Allou, show evidence for lagoonal environments on the landward side of the corridor, which were subject to periodic marine regressions and floodings. These results are reinterpretations of previous work on these sediments, with implications for depositional processes in the Rifian Corridor, Miocene paleoclimate, and the Messinian salinity crisis.

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Holocene coastal landscape development in response to rising sea level in the Central Wadden Sea coastal region

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/njg.2021.10 ◽

2021 ◽

Vol 100 ◽

Author(s):

Martina Karle ◽

Friederike Bungenstock ◽

Achim Wehrmann

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Wadden Sea ◽

Sediment Supply ◽

Sea Level Changes ◽

Landscape Development ◽

Coastal Landscape ◽

The Holocene ◽

Depositional Processes ◽

Holocene Sea Level

Abstract The Holocene sea-level rise has led to significant changes in present-day coastal zones through multifold retrogradational and slightly progradational displacements of the mainland coastline. During the course of this postglacial transgression, sediments characteristic of coastal environments accumulated first in palaeovalleys of the pre-Holocene landscape and later on the subsequently developed coastal plain. Based on a compilation of sedimentological, lithological and litho-chronostratigraphical data of more than 1200 sediment cores, we generated four palaeogeographic maps of the coastal zone of the central Wadden Sea to document with a high spatial resolution the landscape changes during characteristic phases of the Holocene sea-level rise, i.e. the periods 8600–6500 cal BP, 6500–2700 cal BP, 2700–1500 cal BP and 1500–1000 cal BP. Along three cross-sections, representing different hydrodynamic conditions and exposure, we exemplify how the Holocene landscape development and sedimentary facies types are controlled by the local palaeorelief, sea-level changes, sediment supply, accommodation space, the morphodynamic impact of channel shifts, and their erosion base. This leads to a better understanding of main factors controlling the local depositional processes of the coastal landscape along the central Wadden Sea during the Holocene transgression.

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