Quaternary climates and sea levels of the u.s. Atlantic coastal plain

Uranium-series dating of corals from marine deposits of the U.S. Atlantic Coastal Plain coupled with paleoclimatic reconstructions based on ostracode (marine) and pollen (continent) data document at least five relatively warm intervals during the last 500,000 years. On the basis of multiple paleoenvironmental criteria, we determined relative sea level positions during the warm intervals, relative to present mean sea level, were 7 +/- 5 meters at 188,000 years ago, 7.5 +/- 1.5 meters at 120,000 years ago, 6.5 +/- 3.5 meters at 94,000 years ago, and 7 +/- 3 meters at 72,000 years ago. The composite sea level chronology for the Atlantic Coastal Plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200,000 years. Hydroisostatic adjustment from glacial-interglacial sea level fluctuations, lithospheric flexure, and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies. Alternatively, current eustatic sea level estimates for the middle and late Quaternary may require revision.     

Thorium-230 ages of corals and duration of the last interglacial sea-level high stand on oahu, hawaii

Thorium-230 ages of emergent marine deposits on Oahu, Hawaii, have a uniform distribution of ages from approximately 114,000 to approximately 131,000 years, indicating a duration for the last interglacial sea-level high stand of approximately 17,000 years, in contrast to a duration of approximately 8000 years inferred from the orbitally tuned marine oxygen isotope record. Sea level on Oahu rose to >/=1 to 2 meters higher than present by 131,000 years ago or approximately 6000 years earlier than inferred from the marine record. Although the latter record suggests a shift back to glacial conditions beginning at approximately 119,000 years ago, the Oahu coral ages indicate a near present sea level until approximately 114,000 years ago.     

Quaternary raised coral-reef terraces on sumba island, indonesia

A spectacular sequence of coral-reef terraces (six steps broader than 500 meters and many minor substeps) is developed near Cape Laundi, Sumba Island, between an ancient patch reef 475 meters high and sea level. Several raised reefs have been dated with the electron spin resonance and the uranium-series dating methods. The uplift trend deduced from these reefs is 0.5 millimeter per year; most terraces, although polycyclic in origin, appear to correspond to specific interglacial stages, with the oldest terrace formed 1 million years ago. This puts them among the longest and most complete mid-Quaternary terrace sequences.     

The Phanerozoic record of global sea-level change

We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 +/- 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10(4)- to 10(6)-year scale, but a link between oxygen isotope and sea level on the 10(7)-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).     

Rapid flooding of the sunda shelf: A late-glacial sea-level record

The increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable Sunda Shelf in Southeast Asia. The time from 21 to 14 thousand calendar years before the present has been poorly covered in other records. The record generally confirms sea-level reconstructions from coral reefs. The rise of sea level during meltwater pulse 1A was as much as 16 meters within 300 years (14.6 to 14.3 thousand years ago).     

Evidence for Glacial Control of Rapid Sea Level Changes in the Early Cretaceous

Lower Cretaceous bulk carbonate from deep sea sediments records sudden inputs of strontium resulting from the exposure of continental shelves. Strontium data from an interval spanning 7 million years in the Berriasian-Valanginian imply that global sea level fluctuated about 50 meters over time scales of 200,000 to 500,000 years, which is in agreement with the Exxon sea level curve. Oxygen isotope measurements indicate that the growth of continental ice sheets caused these rapid sea level changes. If glaciation caused all the rapid sea level changes in the Cretaceous that are indicated by the Exxon curve, then an Antarctic ice sheet may have existed despite overall climatic warmth.     

Critical depth for the survival of coral islands: effects on the hawaiian archipelago

Coral islands drown when sea level rise exceeds the maximum potential of coral reefs to grow upward (about 10 millimeters per year). During the Holocene transgression (18,000 years ago to present) sea levels rose at rates of up to 10 to 20 millimeters per year, and most coral island reefs situated deeper than a critical depth of30 to 40 meters below present day sea level drowned. Coral islands that did not drown during the Holocene transgression apparently all developed on antecedent foundations shallower than critical depth. During low stands in sea level during the Pleistocene, these islands were elevated and subject to subaerial erosion. Today, in the Hawaiian Archipelago, the depth of drowned banks is inversely related to summit area; smaller banks are progressively deeper, evidently because of erosional truncation during low sea level stands. Bank summit area may therefore be an important factor determining the failure or success of coral islands.     

Rapid fluctuations in sea level recorded at huon peninsula during the penultimate deglaciation

About 140,000 years ago, the breakup of large continental ice sheets initiated the Last Interglacial period. Sea level rose and peaked around 135,000 years ago about 14 meters below present levels. A record of Last Interglacial sea levels between 116,000 years to 136, 000 years ago is preserved at reef VII of the uplifted coral terraces of Huon Peninsula in Papua New Guinea. However, corals from a cave situated about 90 meters below the crest of reef VII are 130, 000 +/- 2000 years old and appear to have grown in conditions that were 6 degreesC cooler than those at present. These observations imply a drop in sea level of 60 to 80 meters. After 130,000 years, sea level began rising again in response to the major insolation maximum at 126,000 to 128,000 years ago. The early (about 140,000 years ago) start of the penultimate deglaciation, well before the peak in insolation, is consistent with the Devils Hole chronology.     

Ice volume and sea level during the last interglacial

During the last interglacial period, ~125,000 years ago, sea level was at least several meters higher than at present, with substantial variability observed for peak sea level at geographically diverse sites. Speculation that the West Antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice-sheet dynamics during this time interval. We provide an internally consistent database of coral U-Th ages to assess last interglacial sea-level observations in the context of isostatic modeling and stratigraphic evidence. These data indicate that global (eustatic) sea level peaked 5.5 to 9 meters above present sea level, requiring smaller ice sheets in both Greenland and Antarctica relative to today and indicating strong sea-level sensitivity to small changes in radiative forcing.     

Holocene sea-level curves for santa monica shelf, california continental borderland

A curve is constructed showing changes in sea level at the Santa Monica shelf over the past 18,000 years. The curve is based on radiocarbon dates, sedimentologic data, and high-resolution seismic stratigraphic analysis of late Quaternary terrace deposits. Sea level was 117 meters below its present position about 18,000 years ago. During the first 8000 years of the Flandrian transgression, sea level rose to at least 24 meters, fell to about 46 meters, and then rose to 20 meters, all below present sea level. Subsequently, sea level rose more slowly and without discernible interruption to its present position.     

Otolith delta 18O record of mid-Holocene sea surface temperatures in Peru

Peruvian sea catfish (Galeichthys peruvianus) sagittal otoliths preserve a record of modern and mid-Holocene sea surface temperatures (SSTs). Oxygen isotope profiles in otoliths excavated from Ostra [6010 +/- 90 years before the present (yr B.P.); 8 degrees 55'S] indicate that summer SSTs were approximately 3 degrees C warmer than those of the present. Siches otoliths (6450 +/- 110 yr B.P.; 4 degrees 40'S) recorded mean annual temperatures approximately 3 degrees to 4 degrees C warmer than were measured under modern conditions. Trophic level and population diversity and equitability data from these faunal assemblages and other Peruvian archaeological sites support the isotope interpretations and suggest that upwelling of the Peru-Chile current intensified after approximately 5000 yr B.P.     

Insular erosion, isostasy, and subsidence

Organic reefs and shore erosion record the intersection of sea level with islands. From this record it is possible to reconstruct the history of vertical movement of the islands and the adjacent deep sea floor, including midplate swells. As judged by coral thickness, islands with barrier reefs sink as though they were on thermally youthful crust regardless of the actual age. Reefless islands do not sink until truncated by erosion. Apparently, thermal subsidence is balanced by isostatic uplift in response to erosion. Barrier reefs prevent wave erosion of encircled volcanoes and capture products of stream erosion so that isostatic uplift is eliminated. Insular shelves widen initially at rates of 0.6 to 1.7 kilometers per million years; the rates decrease with time. Thus the subsidence of islands depends on the size of the is land and the presence of reefs, and it may not always be the same as that of the surrounding oceanic crust.     

Uplifted marine terraces along the alpine fault, new zealand

Three types of evidence indicate that marine terraces are widespread in the Southern Alps of New Zealand. (i) Remnants of shore platforms occur as distinct levels of notched ridge crests and flat summits; degraded sea cliffs are common. (ii) Scattered quartz beach pebbles occur on 16 of 18 levels of exhumed shore platforms in the Fox- Franz Josef type area to altitudes as high as 1700 meters. (iii) Altitudinal spacings of New Zealand terrace flights allow correlation with 18 dated global marine terraces at New Guinea, which were formed during glacio-eustatic highstands of sea level within the last 336 x 10(3) years. Inferred uplift rates at Fox-Franz Josef increased from 3.2 to 7.8 meters per 10(3) years since about 135 x 10(3) to 140 x 10(3) years ago, presumably because of increased convergence between the Pacific and Australian plates.     

Eustatic sea level 120,000 years ago on oahu, hawaii

Extensive dating of the fossil corals associated with the Waimanalo shoreline on Oahu has shown that 120,000 years ago the ocean was approximately 7.6 meters above its present level. Corals grown during that time constitute a major portion of the subaerial reef-derived material on the island, with exposures ranging from about 10 meters to near sea level. This evidence corroborates the notion that 120,000 years before the present was the last time during which the sea stood significantly higher than it does today. The reported benches at 3.7, 1.5, and 0.6 meters, if not of Recent origin, could be features created by brief halts of the sea during rapid regression shortly after the Waimanalo high stand.     

Ocean warming and sea level rise along the southwest u.s. Coast

Hydrographic time-series data recorded during the past 42 years in the upper 500 meters off the coast of southern California indicate that temperatures have increased by 0.8 degrees C uniformly in the upper 100 meters and that temperatures have risen significantly to depths of about 300 meters. The effect of warming the surface layer of the ocean and there by expanding the water column has been to raise sea level by 0.9 +/- 0.2 millimeter per year. Tide gauge records along the coast are coherent with steric height and show upward trends in sea level that vary from about 1 to 3 millimeters per year.     

Sea-level lowering during the illinoian glaciation: evidence from a bahama "blue hole"

Stalagmites have been recovered from 45 meters below sea level in an underwater karstic cave ("blue hole") near Andros Island in the Bahamas. Uranium series ages, corrected for contamination of the sample by young marine carbonate replacements, show that the speleothem was deposited between 160,000 and 139,000 years before the present. This period corresponds to the Illinoian glacial event and demonstrates that sea level must have been lowered by at least 42 meters (allowing for subsidence) from its present position during this time.     

Coral record of equatorial sea-surface temperatures during the penultimate deglaciation at huon peninsula

Uplifted coral terraces at Huon Peninsula, Papua New Guinea, preserve a record of sea level, sea-surface temperature, and salinity from the penultimate deglaciation. Remnants have been found of a shallow-water reef that formed during a pause, similar to the Younger Dryas, in the penultimate deglaciation at 130,000 +/- 2000 years ago, when sea level was 60 to 80 meters lower than it is today. Porites coral, which grew during this period, has oxygen isotopic values and strontium/calcium ratios that indicate that sea-surface temperatures were much cooler (22 degrees +/- 2 degreesC) than either Last Interglacial or present-day tropical temperatures (29 degrees +/- 1 degreesC). These observations provide further evidence for a major cooling of the equatorial western Pacific followed by an extremely rapid rise in sea level during the latter stages of Termination II.     

Recent emerged beach in eastern Mexico

A bluff on the eastern coast of Mexico reveals a cross section through an ancient beach deposit now lying 4 meters above sea level. Radio-carbon dates on the shells within the deposit reveal an age of 1940 years. The deposit appears to be valid evidence for submergence greater than that of the present, but whether that submergence was due to a higher eustatic stand of the sea or whether there has been an uplift of the land since that time cannot yet be determined.     

Holocene mean uplift rates across an active plate-collision boundary in taiwan

Samples of Holocene fossil coral from uplifted reefs of three tectonically distinct, yet geographically proximal regions of Taiwan have been dated by uranium-series and (14)C isotopes. Applying corrections for altitude change caused by sea level fluctuations enables evaluation of long-term average Holocene uplift rates for three areas across an active convergent margin: (i) the Hengchun Peninsula of the Eurasian tectonic plate; (ii) the Eastern Coastal Range of Taiwan, a plate boundary; and (iii) two offshore islands, Lanyu and Lutao, both situated on the leading edge of the adjoining Philippine Plate. The data indicate that while all three areas have experienced uplift through the Holocene, plate collision has caused significantly higher uplift rates in the region directly along the plate boundary.     

Holocene sea level changes at the coast of dor, southeast mediterranean

Geological, geomorphological, and archeological data of changes in sea level during the Holocene at the Mediterranean coast of Dor provide a eustatic curve of the region. This curve shows that sea level was approximately 2 meters below the present level 4000 years ago, rose to 1 meter below the present level 3000 years ago, and was 1 meter higher than the present level 1500 years ago. It then dropped to 1 meter below the present level about 800 years ago.