Nivation Hollows Research Articles

Kalkanlı Dağlarında Kar Yaması Erozyonu İle Oluşan Nivasyon Oyukları

Nivasyon oyukları, kar yaması erozyonu ile oluşan bir aşınım şeklidir. Bu aşınma; kar yamaları altında, detritik nitelikteki zeminin sığ üst zonunda meydana gelen donma-çözülme döngü süreci ile gerçekleşir. Nivasyon süreci olarak tanımlanan bu aşınma; iklim, jeomorfoloji, zeminin tekstür ve strüktür özellikleri ile bitki örtüsü özelliklerinin kontrolünde gelişir. Kar yaması; hem sıcaklığın gün içinde donma ve çözülme döngüsü içinde değişmesi için termal koruyuculuk yaparak, hem de nivasyon sürecinin çalışması için gerekli olan suyun teminine katkı yaparak aşınmanın yıl içindeki etki süresi ve şiddeti üzerinde önemli rol oynar. Bu çalışmada; nivasyon oyukları ele alınarak, Kalkanlı Dağları’ndan (Trabzon, Gümüşhane) kaynağını alan Yanbolu Deresi yukarı çığırı 2000-2200m yükselti kademesindeki nivasyon oyukları örneklemelerinde onların oluşum ve gelişimlerinin açıklanması amaçlanmıştır. Araştırma kapsamında; yüzey analizleri için 1m yersel çözünürlükteki topografik veritabanı drone verisinden üretilmiştir. Çalışma sahasının nivasyon koşullarının değerlendirilmesi amacıyla; Meteoroloji Genel Müdürlüğü’nden temin edilen, 2050m yükseklikteki Torul/Zigana Kayak Merkezi (İstasyon no: 17696) meteoroloji istasyonu iklim verileri kullanılmıştır. Yüzey analizleri için ArcMap 10.7 yazılımı tercih edilmiştir. Arazi çalışmasında nivasyon oyukları incelenerek, ölçümler Garmin Etrex 10 El Tipi GPS ile gerçekleştirilmiştir. Ayrıca Google Earth görüntülerinden de faydalanılmıştır. Nivasyon oyuklarının oluşum ve gelişimlerine ait daha önceki araştırmaların bulgu ve sonuçları; araştırma sahasındaki örnekler ile karşılaştırmalı olarak değerlendirilmiştir. Nivasyon gelişiminin güncel bir jeomorfolojik süreç olması nedeni ile sahanın güncel iklim özellikleri dikkate alınarak, nivasyon süreci perspektifinde değerlendirilmiştir. İklim verilerinin nivasyon sürecinin aktif olmasını desteklediği görülmüştür. Arazi çalışmaları ile elde edilen sahanın jeomorfolojik özellikleri, zeminin tekstür ve strüktür özellikleri, orman örtüsünden yoksun alpin çayır katı hakkındaki bulgular; 2000-2200m yükselti kademesinde halen kar yaması erozyonunun devam ettiğine işaret etmektedir. Arazi çalışmasında, nivasyon oyuklarının enine, boyuna ve dairesel türleri tespit edilmiş olup, bunlar karakteristik özelliklerine göre başlangıç, gençlik ve olgunluk gelişim aşamaları şeklinde sınıflandırılmıştır. Sahada gözlenen nivasyon oyukları genellikle başlangıç ve gençlik gelişim aşamalarında olduğu anlaşılmaktadır. Sahada görülen olgunluk gelişim aşamasındaki dairesel nivasyon oyuğu; Dipsizgöl nivasyon sirki’dir. Nivasyon sirk göllerin ideal bir proksi kapanı olduğunu ve geçmişin coğrafi arşivini sakladıklarını, Dipsizgöl tabanına ait kurtarılmış sedimentlerinin analizleri doğrulamıştır. Bu bilimsel öneminin yanı sıra nivasyon sirk göllerinin korunması gereken birer doğal miras olduğu da kabul edilmelidir.

Long-term nivation rates, Cathedral Massif, northwestern British Columbia

Cryoplanation terraces (CTs) are large (3000–800 000 m2) erosional landforms found in upland periglacial environments. Two hypotheses for the formation of CTs are supported in contemporary literature: (1) CT formation is controlled primarily by geologic structure; and (2) CTs are climatically controlled through nivation, a suite of erosional processes associated with late-lying snowbanks. A persistent question in periglacial geomorphology is whether nivation can produce CT-scale landforms. This paper examines the unusual deglaciation history of “Frost Ridge” on the Cathedral Massif, northwestern British Columbia, to estimate long-term denudation attributable to nivation processes active since the last glacial maximum. Frost Ridge forms one flank of an east–west-oriented glacial valley. During deglaciation, marginal drainage created V-shaped erosional notches on both valley walls. Minimization of solar radiation on the steep north-facing wall (Frost Ridge) allowed snowbanks to accumulate and persist in the marginal drainage features and nivation processes to erode the slope. Today, several large nivation hollows (incipient CTs) are present near the summit of Frost Ridge, while the V-shaped marginal drainage features are preserved at lower elevations and on the opposite, south-facing valley wall. A high-resolution survey using an unmanned aerial vehicle (UAV) allowed volumes of marginal drainage and incipient terrace features to be compared. Based on this volumetric comparison, denudation rates are estimated to range from 4.2 to 125.8 mm/kyr, which are comparable with relatively short-term nivation rates reported from Antarctica and mid-latitude alpine periglacial areas.

Little Ice Age debris lobes and nivation hollows inside Ubehebe Crater, Death Valley, California: Analog for Mars craters?

The 250m-deep, Ubehebe Crater is the youngest (<1000years) and largest (800m-wide) phreatomagmatic crater of the Ubehebe maar field of northern Death Valley, California, USA. The crater is blanketed by loose, unconsolidated ejecta debris and prominent tongue-shaped, steep-fronted debris lobes up to 200m long occur at the base of the crater's steep northeast-facing interior slope. Geomorphological observations, sedimentological analysis of outcrops and a ground penetrating radar survey, show the largest lobe to be composed of downslope-dipping progradational beds of ejecta resulting from repeated downslope avalanching (‘grain flow’) and cohesive debris flow inconsistent with an origin of the lobe as a singular coherent slump or flow. Large oval depressions on the upper surface of lobes are interpreted as relict nivation hollows occupied by former seasonal snow patches during recent Little Ice Age cooling (c. ~700year BP) when numerous rock glaciers and other periglacial landforms formed at high elevations in surrounding mountains. Lobes are interpreted as protalus ramparts formed when loose, non-cohesive ejecta from the steep unstable backwall of the crater moved downslope across snow patches and accumulated around their outer margins. Snow patch and lobe formation is considered to be a function of the local aspect-related meteorology of the crater's interior involving shading of northeast-facing interior slopes, radiative cooling and ponding of cold air, enhanced snow accumulation in the lee of the steep backwall combined with the availability of large volumes of loose ejecta. Ubehebe Crater and its lobes expand the geomorphic record of cool climate processes in Death Valley, the most well-known being the winter-ice facilitated ‘sliding boulders’ of Racetrack Playa. Having formed in an extreme environment, lobes offer an accessible terrestrial analog for poorly-understood debris lobes within Martian impact craters.

Dinámica actual de los nichos de nivación del Alto Sil (Cordillera Cantábrica)

From 2003 to 2009 it has been tracked snowpatches in Alto Sil, in the Cantabrian Mountains. This work allowed us to locate 8 nivation hollows in this area. Currently 6 of them could be considered as active and 2 of them as inactive. A more detail study around Joyas del Nevadín and Valdeiglesia nivation hollows, allowed us to check the snow erosion activity. It was observed an strong relation between the quantity of snow and the dinamic of the nivation hollow. The snow sliding provokes nival striae and clast displacements. Besides, the erosion of rock outcrops is intense in this area. In these locations, it has also been analyzed teh duration of the snow cover which seems to be reduced in the last 20-30 years, probably due to a decrease in the snow volume in these mountains and to changes on land uses.

Periglacialne in ledeniške oblike v zahodnem delu Pohorja

Nedavna geomorfološka raziskovanja na vzhodnem Pohorju so prinesla nova spoznanja o periglacialnih in ledeniških reliefnih oblikah na tem območju. Na podlagi teh ugotovitev so sledile raziskave podobnih pojavov na zahodnem Pohorju, predvsem krioplanacijskih teras in nivacijskih kotanj. Terenske raziskave so razkrile tudi obstoj potujočih skal, kamnitih tokov, blockmeerov in krnice pod Ribniškim jezerom.

Periglacialne oblike na Pohorju

Za razliko od dobro raziskane pleistocenske poledenitve so periglacialni pojavi v Sloveniji slabo preučeni, saj zaradi prevlade karbonatnih kamnin v visokogorju niso posebno opazni. Drugače je na Pohorju, zgrajenem iz magmatskih in metamorfnih kamnin, ki zaradi premajhne višine ni bilo poledenelo, pač pa so bili aktivni periglacialni procesi. V članku so prvič predstavljene nekatere periglacialne oblike na Pohorju, predvsem nivacijske kotanje v vršnih delih, in krnica Jezerc, v kateri je ob višku poledenitve obstajal doslej nepoznan manjši ledenik.

Cryogenic landforms in the Sierras de Alvear, Fuegian Andes, subantarctic Argentina

AbstractA preliminary survey of periglacial landforms found in the Monte Alvear region of the Fuegian Andes, subantarctic Argentina has revealed the presence of nivation hollows, subnival ‘boulder’ (clast) pavements, protalus ramparts, debris lobes, patterned ground and cryo‐ejected clasts. With the exception of debris lobes and cryo‐ejected clasts, all the landforms show some degree of activity and are, therefore, considered as indicators of present‐day cryonival morphodynamics at higher elevations in these mountains. A number of small tors, while not necessarily periglacial in origin, are also apparently experiencing cryogenic weathering. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Nivation forms and processes in unconsolidated sediments, NE Greenland

In the periglacial unconsolidated sediment landscape of Zackenberg in High Arctic NE Greenland, perennial and seasonal snowpatches dominate the geomorphological development in large areas and control the distribution of the vegetation. The existence and distribution of snowpatches and their associated landforms are mainly controlled by the dominating winter wind direction and the amount of snow precipitation, with aspect exerting much less influence. This makes them an important source of information on past environmental change, and knowledge of the combination of geomorphological processes and forms that result from their existence is thus essential. The main nivation processes are backwall failure, sliding and flow, niveo-aeolian sediment transport, supra- and ennival sediment flows, niveo-fluvial erosion, development of pronival stone pavements, accumulation of alluvial fans and basins, and pronival solifluction. The importance of failure, sliding and flow in the continuous retrogressive extension of nivation hollows and niches is emphasized under the term backwall failure. A morphological assemblage of landforms clearly demonstrates the direct nival sediment transfer link between the eroded nivation hollows, their associated meltwater eroded channels and the pronival alluvial fans or basins. All landform elements and their formative processes are integrated into a comprehensive model. © 1998 John Wiley & Sons, Ltd.

Pereletki and the initiation of glaciation in Siberia

Abstract Modern glaciers present in northern Siberia, adjacent to the Arctic Ocean littoral, develop through the gradual accumulation of windblown snow and firn in river valleys and other depressions. Such snow glaciers (“pereletki”) are largely ephemeral in nature, and produce landscapes dominated by nivation hollows and other snow-related landforms. Deposits associated with pereletki include nival, nival-solifluctionary, and fluvio-nival units. The modern pereletki are considered to represent an initial form of glaciation, and their development can be regarded as an analogue for the formation of nival deposits commonly attributed to a more extensive Sartanian glacial event. Late Quaternary glacial events in Siberia involved both alpine and piedmont glaciation, and widespread development of pereletki in lowland areas. Distinguishing between features and sediments produced by glacial ice, and those attributable to ephemeral pereletki, is necessary for accurate assessment of Late Quaternary glaciation in Siberia

Les nardaies à Trifolium alpinum des Monts du Forez et leur biotope à congère tardive

Summary A new association of chionophilous grassland of Nardion, Trifolio alpini—Nardetum strictae Thébaud 1992 is depicted in the “Monts du Forez”, a low range mountain in the Massif Central, France. A floristic comparison with other similar Nardus—communities of the Massif central, Vosges (France) and the Schwarzwald (Germany) is attempted. This specific non widespread poor in species community occurs on the upper sites, over 1460 m in large nivation hollows. This biotope is dealt with several measurements, performed at the Col de la Chamboîte. From these, it can be inferred the persistance of a late snow cover and the pregnance of this factor in the development of this type of vegetation. Other important phenomena are clearly pointed out: creep and mechanical pressure of the snowbank, frost creep in the soil, and local severe thermal conditions. The authors emphasize the biological interest of this mountain zone ecosystem, poorly modified by human action.

Present‐day periglacial microforms in the Lesotho Highlands: Implications for present and past climatic conditions

AbstractA variety of active periglacial microforms have been identified in the vicinity of Tlaeeng Pass (3275 m a.s.l.) in the Lesotho Highlands. These include thufa (both earth and stone‐cored varieties), terracettes, stone polygons and patterned ground. Ground ice within the saturated zone of soil profiles is clearly evident during the winter season, and pebbles perched on needle ice up to 5 cm in length are common. Although possible relict periglacial landforms (such as nivation hollows and protalus ramparts) have been recorded in the area, their identification and, hence, associated climatic inferences is problematic.The presence of active features clearly indicates present‐day periglacial activity, with the variety of forms resulting from diurnal or seasonal freeze‐thaw cycles. Considering a widely accepted global decrease in temperature during the Quaternary, a severity of temperatures greater than what is experienced under present marginal periglacial conditions can be projected for the Lesotho Highlands. However, past moisture regimes are more difficult to project from present‐day features, and this problem is exacerbated by the general paucity of clearly defined diagnostic relict forms.

Nivation hollows and valleys in the fossil coast cliff Landborgen at Helsingborg, South Sweden

Johnsson, Gunnar: Nivation hollows and valleys in the fossil coast cliff Landborgen at Heisingborg, South Sweden. Geografisk Tidsskrift 91: 26–37. Copenhagen 1991. In the fossil coast cliff Landborgen at Helsingborg North- West Skane (Scania), there are many hollows and broad valleys which begin blind with a semicircular back rim. These hollows and valleys were probably formed mainly by nivation in the bedrock of Lias sandstone and shale. The hollows mostly have a cirque form with an opening towards the cliff. Some of them continue as broad valleys containing a rill of water. Most of the main nivation hollows and valleys are older than the last phase of the Weichselian glaciation as indicated by the fact that they contain till or morainic boulders from the north eastern ice, the main ice stream in Skane during the last glaciation. Hydro-thermal water has made hollows and rill water small valleys in the cliff where the nivation processes begun. The nivation processes were caused by drifting snow from the e...

Pleistocene deposits of the South Wales Coalfield and their engineering significance

Abstract The importance of glaciation in the modification of landscape in the South Wales coalfield has long been acknowledged. The effect of periglacial conditions has never been fully assessed, even though these are of enormous relevance to the geomorphology and to the prediction of the engineering characteristics of the superficial deposits. Examination of field relationships and sedimentology has proved the presence, in valley-floors, of glacial lodgement tills, meltout tills and associated water-lain deposits. On lower valley-sides, however, a large proportion of the drift has moved downslope by gelifluction or as mudflows. These redistributed sediments contain silt bands which can cause side-slope collapse in cuttings. They also extend over valley-floors and may conceal glaciolacustrine deposits which can contain water at artesian pressures. Higher valley-side slopes and hilltops show extensive modification by periglacial processes, and there are solifluction terraces and nivation hollows. A good understanding of depositional processes is required for any investigation of slope stability.

Topographic control of vegetation in a mountain big sagebrush steppe

Mountain big sagebrush steppes in Wyoming have strong spatial patterning associated with topography. We describe the spatial variability of vegetation in a sagebrush steppe, and test the relationship between topography and vegetation using canonical correlation. Results of the analysis suggest that the main control over vegetation distribution in this system is wind exposure. Exposed sites are characterized by cushion plant communities and Artemisia nova, and less exposed sites by the taller sagebrush species Artemisia tridentata ssp. vaseyana. Topographic depressions and leeward slopes are characterized by aspen stands and nivation hollows. Measurements of soil microclimate suggest that a major influence of topographic position on vegetation is snow redistribution and its effect on soil moisture and temperature.

Geological and geomorphological indicators of former glaciations in the middle Kolyma Basin

Abstract Extensive glaciations developed in the middle Kolyma basin during the Early and Middle Pleistocene. The types of glaciers and their dimensions have been established on the basis of the distribution of glacial and periglacial deposits, the position of glacial troughs and eroded glacial cirques and nivation hollows. The former glaciers developed in low mountainous and hilly terrain.

Nivation landforms and snowpatch erosion on two massifs in the Northern Highlands of Scotland

Abstract On the An Teallach massif, nivation hollows have developed in Holocene deposits of niveo‐aeolian sand. During the spring melt, considerable quantities of reworked windblown sand and sediment eroded from the lateral scarps are transported by nival meltwater across the gentle (1–5°) treads of the hollows and deposited in small cones downslope. Other processes associated with nivation (accelerated chemical weathering and solifluction, intensive freeze‐thaw activity and snow‐creep transport) are unimportant under present conditions at this site. On Ben Wyvis, nivation landforms take the form of benches developed on frost‐weathered regolith. These benches are relict features; vegetation cover inhibits erosion by nival meltwater and other nivation processes appear to be inoperative. In sum, these observations suggest that present snowpatch erosion at the sites investigated is largely restricted to redistribution of cohesionless sediments by wash, and that even this process is of only local significance.

Nivation landforms in the western Great Basin and their paleoclimatic significance

More than 10,000 nivation landforms occur in the higher mountain ranges of the western Great Basin. They range from small, subtle hollows with head scarps a few meters high and a few tens of meters long to broad, clearly defined terraces as much as 220 m wide bounded by bold, steeply sloping head scarps as much as 30 m high and 1600 m long. Distribution of these nivation hollows is strongly influenced by elevation, slope orientation, local relief, and substrate lithology. About 95% occur between 2200 and 3000 m elevation, and nearly 80% are situated on north-northwest-to east-northeast-facing slopes. They occur mainly in areas of moderately sloping terrain and moderate local relief, and they are preferentially developed on relatively incompetent substrates including terrigenous sedimentary deposits, volcanic and metavolcanic rocks of intermediate composition, and deeply weathered granitoid rocks. Nearly all of these nivation hollows are relict. They are most abundant near areas of late Pleistocene glaciation but rarely occur within such areas. Most are veneered with colluvium and are well vegetated, and many hollows in the Mono Basin area are veneered with volcanic ash at least 700 yr old. Distribution of nivation hollows suggests that (1) the full-glacial nivation threshold altitude (NTA) rose from north to south at 190 m per degree of latitude, subparallel to, and approximately 740 m lower than, the full-glacial equilibrium-line altitude (ELA) and about 1370 m lower than the estimated modern ELA; (2) the difference between the full-glacial and modern ELAs indicates an approximate 7°C full-glacial mean-annual-temperature depression throughout the Great Basin; and (3) the full-glacial mean annual temperature at the NTA is estimated to have been approximately 0° to 1°C, assuming little change in accumulation-season precipitation.

Nivation Hollows and Glacial Cirques in Söderåsen, Scania, South Sweden

The author leads a research project to test his theory of nival erosion and glacial protection of cirque forms in Scania (Rapp 1982 a and b), with comparative studies in Lappland and in middle and south Europe. The project will test the following postulates.The tundra periods in Scania, e.g. the Older and Younger Dryas had permafrost climate with strong effects of snow drifting by easterly and westerly winter storms. This is likely from observations of fossil ice-wedge casts on sandy plains in Scania, and from wind-polished bedrock and blocks with fluting marks, from easterly and westerly directions (G. Johnsson, Å. Mattson, H. Svensson). Large masses of snow were then trapped in the valleys of Söderåsen, forming nivation hollows and glacial cirques. This was also the case during the much longer tundra periods before the advances of the Quaternary main ice sheets over Scania. Small local glaciers and many nivation hollows were formed and grew, before the major ice advances. The canyons, cirques and nivation hollows were protected from destructive ice-sheet scour as their own, local ice-fill, made the large glacier slide over without much erosion (Rapp 1982). Our research program in Lappland will include winter and summer studies of contemporary nivation processes and resulting land forms at selected sites in the mountains of Abisko.

Nivation Hollows and Glacial Cirques in Söderåsen, Scania, South Sweden

Nivation Hollows and Glacial Cirques in Söderåsen, Scania, South Sweden

上越平標山の埋没泥炭層からみた完新世後期の気候変化

Mt. Tairappyo (1, 983m) is a snowy mountain against which the strong winter monsoon blows from the Sea of Japan. Gentle slopes are dominant in this mountain. Due to much snow, tall trees which usually form subalpine conifer forest are not able to grow on the upper part above 1, 600m. Therefore, no subalpine zone exists in this mountain. Instead of tall trees there excel meadows, Sasa fields or scrubs. The result of soil survey in this area showed that the buried peat is widely distributed under the Sasa fields or Graminea-herb meadows. The peat layers are 20_??_30cm thick and are buried under the Kuroboku (Ando) soil or alpine meadow soil (wet type), both with a thickness of about 15cm. The accumulation of the present peat is limited at the bottom of nivation hollows. In these hollows snow patches exist till late June or middle July and supply enough melt water. The wide distribution of the buried peat layer indicates that there was an age when the remaining snow existed more widely in summer season as compared with the present. It seems that the delay of the snow melting is due to first the cool climate in that age. Perhaps it was low temperature at that age, especially in summer season. However, that age seems also to have had a heavier snowfall than the present situation. At present heavy snowfall occurs only in the year when the special strong cold waves hit Japan; it occurs in every ten and odd years. At the age when the buried peat layer was formed due to low temperature in winter, the frequency of the heavy snowfall must have increased, so that much snow existed comparing to the present. The buried peat layers probably accumulated owing to the delay of the snow melting caused by the increase of winter snow and the low temperature in summer. The 14C age of the bottom of the buried peat layer was 3, 100 y. B. P., suggesting that this cool and snowy age would correspond to the Neoglaciation.