scholarly journals Climate, tectonics and beach erosion: the case of Espinho (NW Portuguese coast)

2018 ◽  
pp. 39-50
Author(s):  
Maria da Assunção Araújo
Keyword(s):  
Sea Level ◽  
Little Ice Age ◽  
Beach Erosion ◽  
Ice Age ◽  
Multiple Time ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Portuguese Coast ◽  
Level Curves ◽  
Summer Temperatures

Sea level is a very changeable surface. Furthermore, the land may also be moving, in a slower rate,generating relative sea level changes. The causes of relative sea level changes are variable, but the onesthat cause more intense variations are related to climate.During Little Ice Age (LIA) Northern Hemisphere's summer temperatures fell significantly below theAD 1961–1990 range. This climate situation was responsible for a greater discharge of rivers, whichcould lead to a greater transportation of sediments to the coastline. During these cold periods, sea levelwas lower than in present time. All this could imply a coastline progradation, with the successiveabandon of older beach ridges, reinforcing the sandy supply for dune building. The coastal situationshould be, in some sense, the opposite of the situations that we face today.In present warm period, rivers carry less sediment than during LIA. Moreover, the recent sea level risecontributes to a coastal migration inlands and the erosion of previous beaches and dunes.Our investigation on ancient marine levels and Holocene cemented dunes suggests that the area nearEsmoriz (20 km south of Porto, NW Portuguese coast) is probably subsiding. This possible subsidence,together with recent sea level rise, induced by the end of LIA, could explain the severe coastal erosionthat is taking place at Espinho area (15 km south of Porto) since the middle of the XIX century.This example shows clearly the complexity of relative sea-level changes. Because of this complexity,sea level curves are not similar worldwide, as they depend on the interference of multiple time-scalesphenomena.

Caspian Sea-level changes at the end of Little Ice Age and its impacts on the avulsion of the Gorgan River : a multidisciplinary case study from the southeastern flank of the Caspian Sea

2014 ◽  
pp. 145-155 ◽  
Author(s):  
Abdolmajid Naderi Beni ◽  
Hamid Lahijani ◽  
Morsen Pourkerman ◽  
Rahman Jokar ◽  
Muna Hosseindoust ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Little Ice Age ◽  
Ice Age ◽  
Sea Level Changes ◽  
The Caspian Sea

scholarly journals Late Little Ice Age palaeoenvironmental records from the Anzali and Amirkola Lagoons (south Caspian Sea): Vegetation and sea level changes

2011 ◽  
Vol 302 (3-4) ◽  
pp. 415-434 ◽  
Author(s):  
S.A.G. Leroy ◽  
H.A.K. Lahijani ◽  
M. Djamali ◽  
A. Naqinezhad ◽  
M.V. Moghadam ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Little Ice Age ◽  
Ice Age ◽  
Sea Level Changes ◽  
And Sea Level

The Norse in Greenland and late Holocene sea-level change

Polar Record ◽  
2008 ◽  
Vol 44 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Naja Mikkelsen ◽  
Antoon Kuijpers ◽  
Jette Arneborg
Keyword(s):  
Sea Level ◽  
Little Ice Age ◽  
Late Holocene ◽  
Ice Age ◽  
Documentary Evidence ◽  
Sea Level Changes ◽  
Middle Holocene ◽  
Level Change ◽  
Farming Community ◽  
Holocene Sea Level

ABSTRACTNorse immigrants from Europe settled in southern Greenland in around AD 985 and managed to create a farming community during the Medieval Warm Period. The Norse vanished after approximately 500 years of existence in Greenland leaving no documentary evidence concerning why their culture foundered. The flooding of fertile grassland caused by late Holocene sea-level changes may be one of the factors that affected the Norse community. Holocene sea-level changes in Greenland are closely connected with the isostatic response of the Earth's crust to the behaviour of the Greenlandic ice sheet. An early Holocene regressive phase in south and west Greenland was reversed during the middle Holocene, and evidence is found for transgression and drowning of early-middle Holocene coast lines. This drowning started between 8 and 7ka BP in southern Greenland and continued during the Norse era to the present. An average late Holocene sea level rise in the order of 2–3 m/1000 years may be one of the factors that negatively affected the life of the Norse Greenlanders, and combined with other both socio-economic and environmental problems, such as increasing wind and sea ice expansion at the transition to the Little Ice Age, may eventually have led to the end of the Norse culture in Greenland.

scholarly journals Relative sea-level change in Greenland during the last 700yrs and ice sheet response to the Little Ice Age

2012 ◽  
Vol 315-316 ◽  
pp. 76-85 ◽  
Author(s):  
Antony J. Long ◽  
Sarah A. Woodroffe ◽  
Glenn A. Milne ◽  
Charlotte L. Bryant ◽  
Matthew J.R. Simpson ◽  
...  
Keyword(s):  
Sea Level ◽  
Little Ice Age ◽  
Ice Sheet ◽  
Sea Level Change ◽  
Ice Age ◽  
Relative Sea Level ◽  
Level Change

Little Ice Age subsidence and post Little Ice Age uplift at Juneau, Alaska, inferred from dendrochronology and geomorphology

2003 ◽  
Vol 59 (3) ◽  
pp. 300-309 ◽  
Author(s):  
Roman J. Motyka
Keyword(s):  
Sea Level ◽  
Little Ice Age ◽  
18Th Century ◽  
Tide Gauge ◽  
Ice Age ◽  
Tide Gauge Records ◽  
Relative Sea Level ◽  
Late 18Th Century ◽  
Glaciomarine Sediments ◽  
Sea Cliff

AbstractApplication of dendrochronology and geomorphology to a recently emerged coastal area near Juneau, Alaska, has documented a Little Ice Age (LIA) sea-level transgression to 6.2 m above current sea level. The rise in relative sea level is attributed to regional subsidence and appears to have stabilized by the mid 16th century, based on a sea-cliff eroded into late-Pleistocene glaciomarine sediments. Land began emerging between A.D. 1770 and 1790, coincident with retreat of regional glaciers from their LIA maximums. This emergence has continued since then, paralleling regional glacier retreat. Total Juneau uplift since the late 18th century is estimated to be 3.2 m. The rate of downward colonization of newly emergent coastline by Sitka spruce during the 20th century closely parallels the rate of sea-level fall documented by analysis of local tide-gauge records (1.3 cm/yr). Regional and Glacier Bay LIA loading and unloading are inferred to be the primary mechanisms driving subsidence and uplift in the Juneau area. Climate change rather then regional tectonics has forced relative sea-level change over the last several hundred years.

scholarly journals Holocene sea-level history along eastern-southeastern Brazil

2003 ◽  
Vol 26 ◽  
pp. 13-24
Author(s):  
Louis Martin
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Isotopic Fractionation ◽  
Southeastern Brazil ◽  
Brazilian Coast ◽  
Supporting Evidence ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Level Curves ◽  
High Frequency Oscillations

Relative sea-level curves have been delineated for several sectors of the Brazilian coast. In order to have homogeneous and consistent curves, very short segments of the coastline with the same framework are considered. To minimize systematic errors tied to the particular nature of an indicator, we use the maximum number of different indicators available from former positions of relative sea level. These sea-level curves show that, during the last 7000 years, the central Brazilian coast has been subjected to a submergence phase which lasted until 5100 14C yr BP (5600 cal yr BP), followed by a drop in sea level. This drop in sea level was not continuous but was interrupted by two high-frequency oscillations. The Salvador curve, the most detailed, can be used as a reference for the central portion of the Brazilian coastline. It is now presented with corrections for isotopic fractionation and reservoir effects as well as calibrations for astronomical ages. Additional supporting evidence for the existence of high-frequency oscillations is provided. They are of the same magnitude as is predicted for the future under greenhouse conditions. These data will help us to understand how the coastal systems will respond to these sea-level changes.

Late Quaternary sea level history in the Paulatuk to Bathurst Inlet area, Northwest Territories

1996 ◽  
Vol 33 (3) ◽  
pp. 389-403 ◽  
Author(s):  
Daniel E. Kerr
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Late Quaternary ◽  
Sea Level Changes ◽  
The West ◽  
Relative Sea Level ◽  
Level Curves ◽  
Theoretical Predictions ◽  
Early And Middle Holocene ◽  
Rapid Emergence

The Paulatuk – Bathurst Inlet region experienced rapid deglaciation in response to marine incursion across isostatically depressed terrain during high relative sea level stands. Marine limits, frequently defined by ice-contact deltas, range from 10 m asl in the west to 228 m asl in the east and were formed from approximately 12.5 to 9 ka BP, respectively. Seven relative sea level curves demonstrate that the mainland coast has shown initial rapid emergence, then progressively less emergence, and finally submergence from Paulatuk to Bernard Harbour during the late Holocene. Regions to the east (Richardson Bay to Bathurst Inlet) continue to experience emergence. Sea level curves have shown persistently higher rebound from west to east. The pattern and magnitude of observed postglacial sea level changes are in accord with theoretical predictions. In areas outside the glacial limit, as well as close to but within the glacial limit, relative sea level initially falls during the early and middle Holocene, and then begins to rise due to the migration of the forebulge in late Holocene times. Submergence becomes progressively younger from west to east. Closer to the centre of ice loading, emergence has progressed since deglaciation.

Sign in / Sign up

Export Citation Format

Share Document