Major Retreat Research Articles

Late Pleistocene glacial evolutionary stages in the Gredos Mountains (Iberian Central System)

During the Last Glacial Period (Late Pleistocene) the summits of the Gredos Mountains (Iberian Central System) were covered by plateau glaciers and later evolved into valley and slope glaciers. The evolutionary sequence of these paleoglaciers has been obtained using geomorphological indicators and taking the “principal moraine” as reference. These moraines show the limit between the glaciation and deglaciation periods. In the glaciation period (G), four chronologically sequenced stages have been identified: the local glacial maximum or maximum ice extent (GM); limited retreat (LR); re-advance (RA); and finally major stabilization, the steady-state stage of greatest glacial stability (MS). In the deglaciation period (D), six chronologically sequenced stages have been identified: an absolute retreat which involved regression and stabilization (D1), two major retreat periods (D2 and D4) and two stabilization periods (D3 and D5). Finally, the last stage represents the complete disappearance of the glaciers (D6). This evolutionary sequence allows more precise studies of the ages assigned through numerical dating procedures and of the correlation of the paleoglaciers in the Gredos Mountains with those of other regions.

Holocene glacial variations in Central Patagonia, Aisen, Chile: geomorphological evidences.

During the Holocene, the patagonian glaciers were characterized by geomorphologically registered advances and retreats. This paper presents the geomorphological evolution and evidences of Holocene glacial advances within a segment in Central Patagonia Cordillera. This area will be used as a reference for studying the postglacial paleoclimatic evolution in the southernmost part of South America. The study area is the Rio Blanco basin (45º30’S), located in Central Patagonia (Aisen Region, Chile). Radiometric dating of organic sediments, within terminal moraines, provides preliminary data of two glacial advances. The first one is represented by the Lake Elizalde frontal moraine, which yielded a 14C age of 9.370±50 years BP (10,700 to 10,480 cal. yr BP). According to this chronological age, this glacial event took place in the Early Holocene. This glacial advance, being 100 to 200 years older than that observed immediately south of the study area, on the eastern edge of General Carrera Lake (or Buenos Aires Lake, in Argentina) and approximately 100 years younger than the event recorded in the Puerto Banderas I moraine (Argentino Lake, 50ºS). These results show that the behavior patterns of the Central Patagonia glaciers differ from that observed both in the Lake District (41ºS, Chile) and in the Magallanes District (54°S, Chile), where there are no traces of glacial readvancement recorded during the Early Holocene. After a major retreat to the west, a more recent glacial advance occurred in the Quetro river valley (a tributary river of the Blanco river), at an age prior to 2.250±40 BP (2.340 to 2.150 cal. yr BP), comparable to the cold stage of the Middle Neoglacial, interpreted to have occurred in different parts of Patagonia. Confronting these results with previously published pollen records, we postulate that the cause of both glacier fluctuations is regional variations in the atmospheric temperature and precipitations.

Complex justice: the case of Missouri v. Jenkins

This title shows the federal court's most expensive attempt at school desegregation. In 1987, Judge Russell Clark mandated tax increases to help pay for improvements to the Kansas City, Missouri, School District in an effort to lure white students and quality teachers back to the inner-city district. Yet, even after increasing employee salaries and constructing elaborate facilities at a cost of more than $2 billion, the district remained overwhelmingly segregated and student achievement remained far below national averages.Just eight years later the U.S. Supreme Court began reversing these initiatives, signifying a major retreat from Brown v. Board of Education. In Kansas City, African American families opposed to the district court's efforts organized a takeover of the school board and requested that the court case be closed.Joshua Dunn argues that Judge Clark's ruling was not the result of tyrannical judicial activism but was rather the logical outcome of previous contradictory Supreme Court doctrines. High Court decisions, Dunn explains, necessarily limit the policy choices available to lower court judges, introducing complications the Supreme Court would not anticipate. He demonstrates that the Kansas City case is a model lesson for the types of problems that develop for lower courts in any area in which the Supreme Court attempts to create significant change. Dunn's exploration of this landmark case deepens our understanding of when courts can and cannot successfully create and manage public policy.

Glacier ice mass fluctuations and fault instability in tectonically active Southern Alaska

Across the plate boundary zone in south central Alaska, tectonic strain rates are high in a region that includes large glaciers undergoing wastage (glacier retreat and thinning) and surges. For the coastal region between the Bering and Malaspina Glaciers, the average ice mass thickness changes between 1995 and 2000 range from 1 to 5 m/year. These ice changes caused solid Earth displacements in our study region with predicted values of −10 to 50 mm in the vertical and predicted horizontal displacements of 0–10 mm at variable orientations. Relative to stable North America, observed horizontal rates of tectonic deformation range from 10 to 40 mm/year to the north–northwest and the predicted tectonic uplift rates range from approximately 0 mm/year near the Gulf of Alaska coast to 12 mm/year further inland. The ice mass changes between 1995 and 2000 resulted in discernible changes in the Global Positioning System (GPS) measured station positions of one site (ISLE) located adjacent to the Bagley Ice Valley and at one site, DON, located south of the Bering Glacier terminus. In addition to modifying the surface displacements rates, we evaluated the influence ice changes during the Bering glacier surge cycle had on the background seismic rate. We found an increase in the number of earthquakes ( M L≥2.5) and seismic rate associated with ice thinning and a decrease in the number of earthquakes and seismic rate associated with ice thickening. These results support the hypothesis that ice mass changes can modulate the background seismic rate. During the last century, wastage of the coastal glaciers in the Icy Bay and Malaspina region indicates thinning of hundreds of meters and in areas of major retreat, maximum losses of ice thickness approaching 1 km. Between the 1899 Yakataga and Yakutat earthquakes ( M w=8.1, 8.1) and prior to the 1979 St. Elias earthquake ( M s=7.2), the plate interface below Icy Bay was locked and tectonic strain accumulated. We used estimated ice mass change during the 1899–1979 time period to calculate the change in the fault stability margin (FSM) prior to the 1979 St. Elias earthquake. Our results suggest that a cumulative decrease in the fault stability margin at seismogenic depths, due to ice wastage over 80 years, was large, up to ∼2 MPa. Ice wastage would promote thrust faulting in events such as the 1979 earthquake and subsequent aftershocks.

A high-resolution, 800-year glaciomarine record from Russkaya Gavan', a Novaya Zemlya fjord, eastern Barents Sea

Sediment core ASV-987 from Russkaya Gavan', a tidewater fjord on the northwestern coast of Novaya Zemlya, provides the first multicentury record of sedimentary and hydrographic glaciomarine environments in Russian Arctic with a century-scale resolution. Age is constrained by seven 14C ages securing an especially robust control for the period between c. AD 1370 and 1600. Based on sediment struture, grain size, depositional rates, foraminiferal assemblages and stable isotopes in foraminiferal tests, we reconstruct the changes in fjord sedimentation and circulation in relation to the history of a tidewater glacier connected to the main Novaya Zemlya ice complex. We conclude that a noticeable glacier advance occurred c. AD 1400, contemporaneous with a change in North Atlantic atmospheric circulation inferred from GISP-2 ion-contents data. A major glacier retreat from Russkaya Gavan' occurred by c. AD 1600, succeeded by low sedimentary inputs. Intervals with depleted stable isotopic values, including the core top, may indicate intensified glacier melting. Stronger melting in the 1900s is consistent with an increase in sedimentation rates.

Sediment core from beneath the Amery Ice Shelf, East Antarctica, suggests mid-Holocene ice-shelf retreat

The stability of floating ice shelves is an important indicator of ocean circulation and ice-shelf mass balance. A sub–ice-shelf sediment core collected during the Austral summer of 2000–2001 from site AM02 (69°42.8′S, 72°38.4′E) on the Amery Ice Shelf, East Antarctica, contains a full and continuous record of glacial retreat. The AM02 core site is ∼80 km south of the floating ice shelf edge and contains a 0.5-m-thick Holocene surface layer of siliceous mud and diatom ooze of marine origin. Core data are supportive of sub–ice-shelf circulation models that predict the landward flow of oceanic water, and prove that the landward transport of hemipelagic sediments occurs beneath floating ice shelves over distances of at least ∼80 km. An increase in sea-ice–associated diatom deposition in the upper part of the Holocene suggests that a major retreat of the Amery Ice Shelf to at least 80 km landward of its present location may have occurred during the mid-Holocene climatic optimum.

The future of the welfare state: crisis myths and crisis realities.

Accounts of the future of the welfare state are often presented in crisis terms. Some commentators identify globalization as a force that has already led to a major retreat by the state and is likely to lead to further downsizing of the public sector. Others see the future burden of an aging population as creating huge public expenditure pressures that can be countered only by increased parsimony in most areas of spending. Although both crisis scenarios contain elements of truth, analysis of recent public expenditure trends shows that both are substantially exaggerated as general representations of likely developments over the next two or three decades. However, unnoticed by most commentators, a real, longer-term crisis is beginning to make itself felt. This crisis arises, in part, from the demographic impact of a cultural transformation in the labor market, in progress for several decades. Extreme scenarios of possible consequences over the next 50 to 100 years include population implosion, mass migration, increasingly dangerous eruptions of right-wing populism, and, possibly, territorial conflict between developed and underdeveloped nations. This is not a crisis of the welfare state but rather a crisis for which the welfare state may be an essential part of the answer. The only way Western societies can lessen the future impact of the ongoing cultural transformation of the labor market is through the redesign of welfare state institutions to confront these new challenges.

New Perspectives on Emergency Room Research

On 2 October 1996, FDA issued final regulations allowing for a waiver, in certain cases of emergency research, to requirement of obtaining informed consent from research subjects or their surrogates.[1] Many of commentators on earlier proposed version of these regulations saw them as a major retreat from fundamental moral requirement of obtaining informed consent before research can be conducted. I see them differently. I see them as a mature recognition of existence of multiple values surrounding research effort that need to be balanced in particular cases. What are these values? I would identify at least four: (a) desperate social need for research in emergency setting to test promising treatments for patients presenting with acute crises such as strokes and closed head injuries for which there are few treatments of proven value that can limit damage; (b) potential benefit to some patient-subjects (those in treatment group) who receive promising new therapies if those therapies fulfill their promise; (c) need to protect these individuals from being exploited and harmed by researchers when (as often happens) promising new therapies do not fulfill their promise and turn out to be harmful; (d) right of all individuals not to be used as research subjects without their consent or consent of those who speak for them. In a normal setting, all four of these values can be respected. Needed research takes place after informed consent from those subjects who judge that potential benefits outweigh potential risks. But in an emergency setting, this joint realization of all four values may not be possible. The subjects may not be able to give informed consent and it may not be possible within time in question to find surrogates and obtain their informed consent. Even if consent is obtained from subjects or surrogates, pressures of time, of fears, and of anxieties raise serious questions about meaningfulness of that consent as truly informed or truly voluntary. A recent example illustrates these problems. The National Institutes of Health conducted a trial on tissue plasminogen activator (tPA) for treatment of patients with ischemic strokes.[2] There is a desperate need to find better treatments for that often devastating emergency. This treatment offered great promise (in light of both theoretical plausibility and results of two small open label dose escalation studies), but it involved considerable risks (especially of bleeding). The trial was conducted on patient-subjects treated within first three hours from onset of symptoms (not from arrival in hospital), with half of them being treated within first ninety minutes. While authors report that informed consent was obtained for each patient-subject, very narrow time frame makes it implausible to suppose that those who consented really understood complex issues relevant to participating when they consented. Moreover, their obvious anxieties and fears raise serious questions about whether their consent was a reflection of desperation rather than of voluntary choice. Nevertheless, trial was a great success, and tPA is now recommended for such patients.[3] The FDA's regulations offer a new balancing of related values. They accept possibility that conducting research may be morally licit even if informed consent is not obtained. Instead, research is justified when other three values are present to a sufficient extent. Let me explain by reference to requirements that must be satisfied before waiver is authorized. Under regulations, waivers may only be issued when the human subjects are in a life threatening situation, available treatments are unproven or unsatisfactory, and collection of valid scientific evidence . . . is necessary to determine safety and effectiveness of particular interventions (50. …

THE CBR ADVISORY BOARD COMMENTS ON: CEO Pay, Global Chaos, And a Possible Retreat From Benefits

In the last issue of Compensation & Benefits Review, we reported on the CBR Advisory's Board's take on compensation fads, custom pay plans, and team pay. In this issue, we focus on the following issues: 1. what companies are doing to justify CEO pay; 2. how multinationals are moving expatriates to local or regional pay standards (rather than U.S. standards) and how they're handling high inflation and currency fluctuations; and 3. whether employers are distancing themselves from benefits and whether this, combined with trends in taxation and in the economy, spells the begin ning of a major retreat from the private employer benefits system in the U.S.

International capital mobility and Third World development: Compatible marriage or troubled relationship?

The current surge of foreign capital to the Third World resembles that of the 1970s. The channels are now different but the extra-regional flows are again predominantly to Latin America followed by East Asia. Many of the Latin American countries whose overborrowing brought on the 1980s debt crisis are again overborrowing to compensate for low savings rates and other structural flaws, putting their balance of payments at increasing risk. The likelihood that this time they can handle the rising debt servicing and impending slowing of the inflows sans prolonged crisis or a major retreat from their market liberalization policies is not very high, whereas the East Asian countries appear once more structurally capable of riding out the repercussions from an international financial market pullback.

Limits on the ventilation rate for the deep ocean over the last 12000 years

In this paper we present accelerator radiocarbon measurements on hand picked benthic and planktonic foraminifera separated from two deep sea cores raised from the South China Sea. From the benthic-planktonic age differences we are able to place limits on the extent to which the ventilation rate of the deep Pacific Ocean has changed over the last 12000 years. While much work remains to be done before any definitive answers for the global oceans can be given, these results on cores with sedimentation rates suitably high to avoid major corrections for bioturbation effects suggest that the ventilation rate of the deep Pacific Ocean has remained nearly the same throughout Holocene time. Further, there is no suggestion that the rate was slower during the period of major glacial retreat. These results confirm that the changes in atmospheric14C/C ratio over the last 10000 years owe their origin to radiocarbon production rate changes.

A Major Retreat on the Yellow Rain Battlefront

A Major Retreat on the Yellow Rain Battlefront

Late Paleozoic Cold-Water Carbonate Sedimentation in Tasmania: DISCUSSION

We read the recently published account of Tasmanian Late Paleozoic cold-water carbonate sedimentation (Rao, 1981) with considerable dismay. It is not that we disagree with a cold-water origin for the Berriedale Limestone (and other Tasmanian Late Paleozoic rocks), for this has long been the view of most Tasmanian geologists. Rather we indicate below what we consider to be fundamental errors in Dr'. Rao's understanding of the stratigraphy of Tasmanian Late Paleozoic rocks, and their bearing on what we consider to be a totally untenable model for Berriedale Limestone deposition. In Tasmania rocks of Late Paleozoic age are widespread and display an unmistakable glacial imprint. They constitute the Lower Parmeener Super-Group (Forsyth et al., 1974) which is ahnost everywhere subhofizontal, and rests with profound landscape unconformity on a folded basement of Precambfian and earlier Paleozoic strata intruded by Late Devonian to Early Carboniferous granites (McDougall and Leggo, 1965). Basement surfaces are often scoured, plucked and striated, with exhumed roches moutonndes in rare instances. The subglacial surface had a relief in excess of one thousand meters. Vestiges of this relief remained until their final burial late in the Triassic Period. Without doubt, sometime late in the Carboniferous Period ice covered most of Tasmania. When the ice retreated, thick sequences (sometimes in excess of 500 meters) of massive and unbedded mixtite, tillite, glaciolacustrine rhythmite claystane, outwash conglomerate, and minor turbidite sandstone were deposited in areas of low relief within the basement (David, 1908; GuUine, 1977; Banks, 1981). In the light of recent recommendations concerning the placement of the Carboniferous-Permian boundary (Kemp et al., 1977; Balme, 1980), all these glacigene rtx:ks are wholly Late Carboniferous in age (Truswell, 1978). Following the major ice retreat, most of Tasmania was rapidly flooded by a transgressive sea from the south and east, the initial eustatic rise in sea-level being far more rapid than any isostatic readjustment. Thereafter Tasmania suffered repeated periods of transgression and regression throughout Asselian-Kazanian times, when several hundreds of meters of shallow-water and essentially marine platform sediments were deposited. No subsequent transgression was as widespread areally as the initial post-glacial flooding. Dropstones and lonestones are ubiquitous and can only be satisfactorily explained by ice-rafting. Very rich faunas of very low taxonomic diversity (Clarke and Banks, 1975; Clarke and Farmer, 1976) support the existence of cold-water conditions. Nevertheless, there is no evidence that any part of what is now Tasmania was occupied by ice following the major

Glacial history of western Norway 15,000–10,000 B.P.

The deglaciation patterns of the Bergen and Nordfjord‐Sunnmøre areas in western Norway are described and correlated. In the Bergen area the coast was first deglaciated at 12,600 B.P., with a succeeding re‐advance into the North Sea around 12,200 B.P. Later, during the Allerød, the inland ice retreated at least 50 km, but nearly reached the sea again during the Younger Dryas re‐advance, ending at 10,000 B.P. Sunnmøre was ice‐free during an interstadial 28,000–38,000 B.P. Later the inland ice reached the sea. The final deglaciation is poorly dated in Sunnmøre, while further south in Nordfjord, it started slightly before 12,300 B.P., followed by a major retreat. No large re‐advance of the inland ice occurred during the Younger Dryas. However, in the Sunnmøre‐Nordfjord area many local glaciers formed outside the inland ice during the Younger Dryas. Limnic sediments outside one such cirque glacier have been cored and dated, proving that the glacier did not exist at 12,300‐11,000 B.P., and that it was formed and disappeared in the time interval 11,000–10,000 B.P. (Younger Dryas). The erosion rate of the cirque glacier was 0.9 mm/year.

Greatlakean Substage: A Replacement for Valderan Substage in the Lake Michigan Basin

New evidence from recent field and seismic investigations in the Lake Michigan basin and in the type areas of the Valders, Two Creeks and Two Rivers deposits necessitates revision of late-glacial ice-front positions, rock- and time-stratigraphic nomenclature and climatic interpretations and deglaciation patterns for the period ca. 14,000–7,000 radiocarbon years B.P. The previously reported and long accepted pattern of deglaciation for the Lake Michigan basin started with a regular retreat from the Lake Border Morainic System, with a minor oscillation marked by the Port Huron moraine(s) and then an extensive Twocreekan deglaciation followed by a major (320 km) post-Twocreekan advance (Valders). However, we now record a major retreat between the times of the Lake Border and Port Huron moraines, followed by a gradual retreat from the Port Huron limit and interrupted by a minor standstill (deposition of Manitowoc Till), a retreat (Twocreekan) and a readvance (Two Rivers Till). No Woodfordian or younger readvance was as extensive as had been the preceding one. This sequence argues for a normal, climatically controlled, progressive deglaciation rather than one interrupted by a major post-Twocreekan (formerly Valderan) surge. This revision appears finally to harmonize the geologic evidence and the palynological record for the Great Lakes region. Our investigations show that Valders Till from which the Valderan Substage was named is late-Woodfordian in age. We propose the term “Greatlakean” as a replacement for the now misleading time-stratigraphic term “Valderan”. The type section and the definition of the upper and lower boundaries of the Greatlakean Substage remain the same as those originally proposed for the Valderan Substage but the name is changed.

PALAEOZOIC HISTORY OF THE ST. VINCENT GULF REGION, SOUTH AUSTRALIA

The St. Vincent Gulf Region comprises portions of the Gawler Craton and Adelaide Geosyncline. It extends from Yorke Peninsula and a portion of Investigator Strait (within the craton) to the Mt. Lofty — Kangaroo Island fold belt (inclusive). An area of potential hydrocarbon accumulation exists in a marginal area of the geosyncline adjacent to the craton.After latest Precambrian deformation of Proterozoic strata, Lower Cambrian deposition commenced with transgressive arkoses, overlain by carbonates. The upper portion of the carbonates near or on the craton grade eastwards into mudstones in the geosyncline proper. A major retreat of the sea from marginal areas of the craton and geosyncline occurred during late Lower Cambrian time. The exposed land mass constituted a source for clastics deposited in the remainder of the geosyncline, which was undergoing strong downwarping movements. Intercalated carbonates and clastics of latest Lower Cambrian and Middle Cambrian age document return of the sea to the craton.Deposition in the geosyncline probably terminated during Middle Cambrian time, with pronounced earth movements and regional metamorphism culminating during Ordovician time. The Palaeozoic and Proterozoic rocks are unconformably overlain by Lower Permian and Cainozoic sediments.Three major fault patterns can be recognized in the region. Within most of the western portion, the fault pattern is similar to that of the Gawler Craton. Two later patterns of faulting in the remainder of the region evolved during Upper Proterozoic-Cambrian and Cambro-Ordovician times respectively, as the consequence of pronounced folding. Episodic movements of blocks bounded by faults in the western and northwestern portions of the region were the result of strong compressional forces directed towards the craton. Weaker earth movements also occurred during Lower Permian-Eocene time rejuvenating some of the old structures.

On the statistical characteristics of winds in the sea south of Honshu. (In Japanese; English abstract) : Ito, A., 1962. Bull. Kobe Mar. Obs., 169 (15): 28–33

New evidence from recent field and seismic investigations in the Lake Michigan basin and in the type areas of the Valders, Two Creeks and Two Rivers deposits necessitates revision of late-glacial ice-front positions, rock- and time-stratigraphic nomenclature and climatic interpretations and deglaciation patterns for the period ca. 14,000–7,000 radiocarbon years B.P. The previously reported and long accepted pattern of deglaciation for the Lake Michigan basin started with a regular retreat from the Lake Border Morainic System, with a minor oscillation marked by the Port Huron moraine(s) and then an extensive Twocreekan deglaciation followed by a major (320 km) post-Twocreekan advance (Valders). However, we now record a major retreat between the times of the Lake Border and Port Huron moraines, followed by a gradual retreat from the Port Huron limit and interrupted by a minor standstill (deposition of Manitowoc Till), a retreat (Twocreekan) and a readvance (Two Rivers Till). No Woodfordian or younger readvance was as extensive as had been the preceding one. This sequence argues for a normal, climatically controlled, progressive deglaciation rather than one interrupted by a major post-Twocreekan (formerly Valderan) surge. This revision appears finally to harmonize the geologic evidence and the palynological record for the Great Lakes region. Our investigations show that Valders Till from which the Valderan Substage was named is late-Woodfordian in age. We propose the term “Greatlakean” as a replacement for the now misleading time-stratigraphic term “Valderan”. The type section and the definition of the upper and lower boundaries of the Greatlakean Substage remain the same as those originally proposed for the Valderan Substage but the name is changed.

XI.—The Geology and Vegetation of Late-glacial Retreat Stages in Scotland

SynopsisThe last major retreat stages of the ice in Scotland have been correlated with the different periods of vegetational history as shown by pollen diagrams. The end-moraines can be divided into two stages, the first stage being the Perth Readvance Moraine, during which the ice extended outside the Highlands. The Aberdeen Readvance Moraine probably also belongs to the same stage. During the second stage, here called the Highland Readvance, valley glaciers reached to the mouths of the Highland valleys where small moraine ridges were formed.Samples from mainly lake sediments near the moraine were studied, and the pollen diagrams from them show the general vegetational history of the Late-glacial and Post-glacial periods. The same zones as in other parts of the British Isles are used in the diagrams.The geological and pollen analytical evidence suggests that the Highland Readvance Moraine was formed during the Late-glacial Zone III, and that the Perth Readvance is older than the Alleröd interstadial. The Highland Readvance can now be correlated with the moraines in Scandinavia, the Alps and North America, where they already have been dated.