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1.
冰湖的界定与分类体系——面向冰湖编目和冰湖灾害研究 总被引：4，自引：0，他引：4
冰川湖泊（简称冰湖）不仅是高山区重要的水资源,而且是许多冰川灾害的孕育者和发源地,在冰冻圈科学、气候变化和山地灾害研究中具有重要地位。本文系统讨论了现有冰湖定义及存在的问题,从冰湖编目和冰湖灾害研究视角提出冰湖的定义,指出现有冰湖研究主要是基于“以现代冰川融水为主要补给源或在冰碛垄洼地内积水形成的天然水体”这一冰湖定义的。同时,从冰湖形成机理、地貌形态和空间分布位置将冰湖划分为冰川侵蚀湖（冰斗湖、冰川槽谷湖和其他冰川侵蚀湖）、冰碛阻塞湖（终碛阻塞湖、侧碛阻塞湖、冰碛垄热融湖）、冰川阻塞湖（冰川前进阻塞湖和其他冰川阻塞湖）、冰面湖、冰下（内）湖和其他冰川湖6大类及8个亚类,并给出各冰湖类型相应的遥感判识指标和定量指标,以期建立具有普适性和可操作性的冰湖分类体系。 相似文献
2.
Glacial lakes are not only the important refresh water resources in alpine region, but also act as a trigger of many glacial hazards such as glacial lake outburst flood(GLOF) and debris flow. Therefore, glacial lakes play an important role on the cryosphere, climate change and alpine hazards. In this paper, the issues of glacial lake were systematically discussed, then from the view of glacial lake inventory and glacial lake hazards study, the glacial lake was defined as natural water mainly supplied by modern glacial meltwater or formed in glacier moraine's depression. Furthermore, a complete classification system of glacial lake was proposed based on its formation mechanism, topographic feature and geographical position. Glacial lakes were classified as 6 classes and 8 subclasses, i.e., glacial erosion lake(including cirque lake, glacial valley lake and other glacial erosion lake), moraine-dammed lake(including end moraine-dammed lake, lateral moraine-dammed lake and moraine thaw lake), ice-blocked lake(including advancing glacier-blocked lake and other glacier-blocked lake), supraglacial lake, subglacial lake and other glacial lake. Meanwhile, some corresponding features exhibiting on remote sensing image and quantitative indices for identifying different glacial lake types were proposed in order to build a universal and operational classification system of glacial lake. 相似文献
3.
Glacier retreat is not only a symbol of temperature and precipitation change, but a dominating factor of glacial lake changes in alpine regions, which are of wide concern for high risk of potential outburst floods. Of all types of glacial lakes, moraine-dammed lakes may be the most dangerous to local residents in mountain regions. Thus, we monitored the dynamics of 12 moraine-dammed glacial lakes from 1974 to 2014 in the Poiqu River Basin of central west Himalayas, as well as their associated glaciers with a combination of remote sensing, topographic maps and digital elevation models (DEMs). Our results indicate that all monitored moraine-dammed glacial lakes have expanded by 7.46 km2 in total while the glaciers retreated by a total of 15.29 km2 correspondingly. Meteorological analysis indicates a warming and drying trend in the Nyalam region from 1974 to 2014, which accelerated glacier retreat and then augmented the supply of moraine-dammed glacial lakes from glacier melt. Lake volume and water depth changed from 1974 to 2014 which indicates that lakes Kangxico, Galongco, and Youmojanco have a high potential for outburst floods and in urgent need for continuous monitoring or artificial excavation to release water due to the quick increase in water depths and storage capacities. Lakes Jialongco and Cirenmaco, with outburst floods in 1981 and 2002, have a high potential risk for outburst floods because of rapid lake growth and steep slope gradients surrounding them. 相似文献
4.
喜马拉雅山北坡冰碛湖库容计算及变化——以龙巴萨巴湖为例 总被引：2，自引：0，他引：2
喜马拉雅地区冰湖溃决洪水灾害日益受到人们重视。作为估算冰湖溃决洪峰流量和模拟洪水演进的必要参数之一,冰湖库容量准确计算十分重要。2009 年9 月对西藏定结县龙巴萨巴湖科考时,应用HydroboxTM高分辨率回声测深仪对该湖进行了测深试验,共采集6916 个离散数据点,测得冰湖最深处为101.94 m,平均水深47.50 m。结合同一时段Landsat TM遥感影像解译结果,通过构建不规则三角网模拟龙巴萨巴湖湖盆形态,并计算出该湖2009 年库容量为0.64×108 m3。利用GIS技术对1977-2008 年不同年份的Landsat MSS、地形图、Landsat TM和ASTER遥感影像进行数字化,结果表明近30 年来龙巴萨巴湖长度和面积均呈增加趋势,且自2000 年以来更为显著。利用不同时期龙巴萨巴湖面积和计算的库容量,得到冰碛湖库容-面积计算公式,可为喜马拉雅地区其他冰碛湖库容量估算提供理论参考。龙巴萨巴湖的扩张方向与其母冰川后退方向保持一致。通过对龙巴萨巴湖所在区域中国境内5 个气象站点气温、降水数据的年代际变化分析,表明冰湖规模扩大是气候变暖和冰川退缩的产物。 相似文献
5.
冰湖溃决灾害是青藏高原地区主要的灾害之一。详细了解冰湖的面积和水量变化及其原因, 有助于更准确地确定其溃决的可能性和产生破坏的程度和范围。米堆冰湖为一个典型的冰碛物阻塞冰湖, 1988 年7 月15 日曾发生溃决。本研究利用1980 年1:5 万地形图和DEM、1988 年TM影像、2001 年IKONOS影像以及2001、2007、2009、2010 年ALOS影像, 提取冰湖溃决前后的面积变化, 结合野外实地测得的冰湖水深, 获得冰湖不同时期的水量及其变化。同时, 利用自动水位计, 监测湖泊相对水深的变化及其原因。结果显示, 米堆溃决前面积达到64×104 m2, 水量为699×104 m3, 溃决使得601.83×104 m3的水量溃出, 水位下降了17.18 m, 但溃决口并未达到冰湖最低处, 溃决后仍有97.17×104 m3的水量。近年来, 气温升高融水增加使得冰湖面积和水量不断增加, 按照目前的水量增加速率, 冰湖再次发生溃决的可能性较小, 而在由于其他原因使得冰湖发生堵塞或大量外来物质(冰川断裂、滑坡等)填充进冰湖时, 可能导致冰湖水位急剧上升, 再次发生溃决。 相似文献
6.
The Himalayas are prone to glacial lake outburst floods, which can pose a severe threat to downstream villages and infrastructure. The Zhangmu and Gyirong land treaty ports are located on the China-Nepal border in the central Himalayas. In recent years, the expansion of glacial lakes has increased the threat of these two port regions. This article describes the results of mapping the glacial lakes larger than 0.01 km2 in the Zhangmu and Gyirong port regions and analyzes their change. It provides a comprehensive assessment of potentially dangerous glacial lakes and predicts the development of future glacial lakes. From 1988 to 2019, the glacial lakes in these port regions underwent "expansion", and moraine-dammed lakes show the most significant expansion trend. A total of eleven potentially dangerous glacial lakes are identified based on the assessment criteria and historical outburst events; most expanded by more than 150% from 1988 to 2019, with some by over 500%. The Cirenmaco, a moraine-dammed lake, is extremely prone to overtopping due to ice avalanches or the melting of dead ice in the dam. For other large lakes, such as the Jialongco, Gangxico and Galongco, ice avalanches may likely cause the lakes to burst besides self-destructive failure. The potential dangers of the Youmojianco glacial lakes, including lakes Nos. 9, 10 and 11, will increase in the future. In addition, the glacier-bed topography model predicts that 113 glacial lakes with a size larger than 0.01 km2, a total area of 11.88 km2 and a total volume of 6.37×109 m3 will form in the study area by the end of the 21 century. Due to global warming, the glacial lakes in the Zhangmu and Gyirong port regions will continue to grow in the short term, and hence the risk of glacial lake outburst floods will increase. 相似文献
7.
《地理学报(英文版)》2016,(4)
Inland lakes and alpine glaciers are important water resources on the Tibetan Plateau. Understanding their variation is crucial for accurate evaluation and prediction of changes in water supply and for retrieval and analysis of climatic information. Data from previous research on 35 alpine lakes on the Tibetan Plateau were used to investigate changes in lake water level and area. In terms of temporal changes, the area of the 35 alpine lakes could be divided into five groups: rising, falling-rising, rising-falling, fluctuating, and falling. In terms of spatial changes, the area of alpine lakes in the Himalayan Mountains, the Karakoram Mountains, and the Qaidam Basin tended to decrease; the area of lakes in the Naqu region and the Kunlun Mountains increased; and the area of lakes in the Hoh Xil region and Qilian Mountains fluctuated. Changes in lake water level and area were correlated with regional changes in climate. Reasons for changes in these lakes on the Tibetan Plateau were analyzed, including precipitation and evaporation from meteorological data, glacier meltwater from the Chinese glacier inventories. Several key problems, e.g. challenges of monitoring water balance, limitations to glacial area detection, uncertainties in detecting lake water-level variations and variable region boundaries of lake change types on the Tibetan Plateau were discussed. This research has most indicative significance to regional climate change. 相似文献
8.
Yue Fang Weiming Cheng Yichi Zhang Nan Wang Shangmin Zhao Chenghu Zhou Xi Chen Anming Bao 《地理学报(英文版)》2016,26(4):415-438
Inland lakes and alpine glaciers are important water resources on the Tibetan Plateau. Understanding their variation is crucial for accurate evaluation and prediction of changes in water supply and for retrieval and analysis of climatic information. Data from previous research on 35 alpine lakes on the Tibetan Plateau were used to investigate changes in lake water level and area. In terms of temporal changes, the area of the 35 alpine lakes could be divided into five groups: rising, falling-rising, rising-falling, fluctuating, and falling. In terms of spatial changes, the area of alpine lakes in the Himalayan Mountains, the Karakoram Mountains, and the Qaidam Basin tended to decrease; the area of lakes in the Naqu region and the Kunlun Mountains increased; and the area of lakes in the Hoh Xil region and Qilian Mountains fluctuated. Changes in lake water level and area were correlated with regional changes in climate. Reasons for changes in these lakes on the Tibetan Plateau were analyzed, including precipitation and evaporation from meteorological data, glacier meltwater from the Chinese glacier inventories. Several key problems, e.g. challenges of monitoring water balance, limitations to glacial area detection, uncertainties in detecting lake water-level variations and variable region boundaries of lake change types on the Tibetan Plateau were discussed. This research has most indicative significance to regional climate change. 相似文献
9.
The mechanical denudation rates of 81 large lake basins (lake area > 500 km2) were determined from long-term river loads and erosion maps. Using the drainage area/lake area ratios the mean sedimentation rates of the lakes were calculated for a porosity of 0.3. The mean sedimentation rates of different lake types vary between 0.1 mm/a (glacial lakes, lowland) and 5.4 mm/a (mostly sag basin lakes). The calculated lifetimes of the lakes are based on the lake volumes and mean sedimentation rates, assuming steady-state conditions and solely clastic material. On average, glacial lakes in highlands and fault-related lakes show the shortest lifetimes (c. 70 ka), glacial lakes in lowlands and rift lakes have the longest lifetimes (c. 1 Ma). Some lakes remain unfilled for very long time spans due to rapid subsidence of their basin floors. The calculated lifetimes are compared with those derived from sediment core studies. Most core studies indicate lower mechanical sedimentation rates than the calculated ones because a major part of the incoming sediment is trapped in deltas. However, a number of lakes (e.g., the Great Lakes of North America) show the opposite tendency which is largely caused by extensive shoreline erosion and resuspension. The lifetimes of large glacial lakes often exceed the duration of interglacials. Hence, their lifetimes are restricted by glaciation and not by sediment infill. Rift lakes persist for long time periods which exceed the calculated lifetimes in some cases. Time-dependent subsidence, basin extension, as well as the impact of climate change are briefly described. 相似文献
10.
Monitoring alpine lakes is important for understanding the regional environmental changes caused by global warming. In this study, we provided a detailed analysis of alpine lake changes in the Tianshan Mountains (TS) and discussed their driving forces based on Landsat TM/ETM+/OLI, WorldView-2, Bing, Google Earth, and ASTER imagery, along with climatic data from 1990 to 2015. The results showed that during the study period, the total number and area of alpine lakes in the eastern TS exhibited an increasing trend, by 64.06% and 47.92%, respectively. Furthermore, the continuous expansion of glacial lakes contributed 95.12% and 94.17% to the total increase in the number and area, respectively, of alpine lakes. Non-glacial lakes exhibited only intermittent expansion. Since the 1990s, the new glacial lakes in the eastern TS have been mainly proglacial and extraglacial lakes. Over the past 25 years, eastern TS has experienced a temperature increase rate of 0.47 °C/10a, which is higher than that in other TS regions. The rapidly warming climate and glacier recession are the primary causes of the accelerated expansion of glacial lakes in the eastern TS. 相似文献
11.
RANDY W. DIRSZOWSKY JOSEPH R. DESLOGES 《Geografiska Annaler: Series A, Physical Geography》2010,92(3):393-410
This study assesses Little Ice Age (LIA) lake sediment morphological and geochemical records and moraine chronologies in the upper Fraser River watershed, British Columbia, Canada, to resolve differences in paleoenvironmental interpretation and to clarify sediment production and sediment delivery processes within alpine geomorphic systems. Moose Lake (13.9 km2), situated at 1032 m a.s.l., contains a partially varved record indicating variable rates of accumulation during the last millennium that, in general, coincide with previously documented LIA glacial advances in the region and locally. Dendrochronological assessment of forefield surfaces in the headwaters of the catchment (Reef Icefield) shows that periods of moraine construction occurred just prior to ad 1770, ad 1839 and ad 1883, and some time before ad 1570. Taken collectively, increases in varve thickness within eight Moose Lake sediment cores coincide with documented glacier advances over the twelfth through fourteenth centuries, the eighteenth century, and nineteenth through twentieth centuries. Glacial activity during the sixteenth century is also indicated. While varve thickness variations in proximal and distal sediments clearly reflect glacial activity upstream of Moose Lake, the intermediate varve record is relatively insensitive to these decadal and longer‐term catchment processes. Variations in Ca and related elements derived from glaciated carbonate terrain within the Moose River sub‐catchment (including Reef Icefield) indicate gradually increasing delivery from these sources from the twelfth through twentieth centuries even where the varve thickness record is unresponsive. Elevated carbonate concentrations confirm glacial activity c. ad 1200, ad 1500, ad 1750, and ad 1900. 相似文献
12.
The recognition of ice-marginal deltas constructed during the formation of the Nakina II moraine and a previously unrecognized
spillway, in the vicinity of Longlac, northern Ontario, indicates that existing concepts of ancestral lake level history and
drainage systems in the Lake Superior–Lake Nipigon region is inadequate. Based on isostatically corrected digital elevation
maps, ice-marginal deltas of the Nakina II moraine probably formed at the level of glacial Lake Minong, most likely Minong
III, and not glacial Lake Nakina as has been commonly suggested. In addition, the presence of a spillway near Longlac indicates
that lake water drained southward through the Mullet Outlet–Pic River system immediately following ice-marginal retreat from
the Nakina II moraine and not eastward as previously proposed. Architectural-element analysis of exposures within the spillway
indicates hyperconcentrated outbursts of meltwater produced thick channel-fill elements during flood conditions with peak-velocities
exceeding 3 m/s. Subsequent retreat of ice from the Pic River valley to the east, may have allowed waters of Lake Agassiz,
Lake Barlow–Ojibway, or both, to drain into post-Minong lake levels in the Lake Superior basin. These findings place major
constraints on previously proposed concepts of northeastern or eastern outlets of Lake Agassiz. 相似文献
13.
Leili Saarse 《Journal of Paleolimnology》1990,3(1):1-12
Based on extensive data from a long-term investigation, a new genetic classification of lake basins is proposed for Estonia. Eight lake groups are distinguished, tectonic-denudation, glacial, chemical, fluvial, coastal (neotectonic), telmatogenic, cosmogenic and artificial, containing 13 subgroups and 19 basin types. Also proposed is a new lithological classification of Estonia's organic and calcareous lake sediments, based on analyses of more than 2000 sediment samples from 90 contemporary and 50 late-glacial (extinct) lakes. Of the ca. 1150 Estonian lake basins that formed on mineral substrate, the two largest basins are of preglacial, tectonic-denudation origin, later modified by glaciers. Eight hundred lakes are of glacial origin, and 300 of other origins in the Holocene. In addition, ca 20 000 bog pools formed on peat in the Holocene. Only minerogenous sedimentation occurred in the lakes in the late-glacial period. After that, organic (gyttjas) and/or calcareous sediments have formed. Azonal factors have been largely responsible for the wide variation in Estonia's lacustrine deposits.This article belongs to a series of papers to be published by this journal that was presented in the paleolimnology sessions organized by R. B. Davis and H. Löffler for the XIIth Congress of the International Union for Quaternary Research (INQUA), which took place in Ottawa, Canada in August 1987. Dr. Davis is serving as guest editor of this series. 相似文献
14.
采用1:5万地形图、Landsat MSS/TM/ETM+/OLI遥感影像及数字高程模型数据,利用遥感和地理信息系统技术,并结合狮泉河、和田和于田3个气象站点1968-2013年的气温、降水量数据对松木希错流域的冰川、湖泊面积变化及其原因进行分析。结果表明：① 1968-2013年流域冰川面积不断退缩,由139.25 km2减少至137.27±0.02 km2,共减少1.98±0.02 km2,减少百分比为1.42%,2001年以后冰川退缩速度加快;② 1968-2013年松木希错面积不断扩张,由25.05 km2增加至32.62±0.02 km2,共扩张7.57±0.02 km2,扩张百分比为30.22%,且2001年之后扩张速率加快,在年代际上与冰川的退缩具有较好的耦合性;③ 1968-2013年湖面潜在蒸散量减少和降水增加分别是导致湖泊扩张的第一和第二影响因素,而升温引起的冰川、冻土融水增加有一定贡献,但影响较小且在年际尺度上不显著。 相似文献
15.
青藏高原冰湖研究进展及趋势 总被引：2，自引：0，他引：2
冰湖是由于冰川活动或者退缩产生的融水在冰川前部或者侧部汇集而成的,可分为冰川终碛湖(冰碛阻塞湖)、冰川阻塞湖、冰斗湖和冰蚀槽谷湖。其中分布数量较多、规模较大,且灾害风险较高的是冰川终碛湖。因此,冰川终碛湖是研究冰湖的主要对象。受全球气候变暖的影响,冰湖溃决产生的洪水、泥石流等重大冰川灾害的发生频率有所升高,灾害的影响程度以及范围也有所加大,引起了冰川山地国家的广泛关注。青藏高原内部发育着36793条现代冰川,冰川面积49873.44km2,分别占中国冰川总条数、总面积和冰储量的79.5%、84%和81.6%。在全球气候变暖的大背景下,多数冰川呈加速消融及退缩的态势,导致了冰湖溃决洪水和冰川泥石流等重大冰川灾害发生频率的加剧和影响程度的加大。本文围绕冰湖溃决条件、冰湖稳定性评价、冰湖溃决洪水模拟等几个研究方面,对青藏高原冰湖研究的现状及进展进行了较为系统的总结,并对未来研究趋势进行了展望。 相似文献
16.
末次盛冰期以来中国湖泊记录对环流系统及气候类型的响应 总被引：4，自引：1，他引：3
为了探讨中国长时间尺度湖泊时空演变规律和潜在的驱动机制,本文在柯本气候分区和中国季风—非季风区的划分基础上,对中国34个有明确数据的典型湖泊运行CCSM 3.0气候模拟系统和水量能量平衡模型模拟其水位变化,同时利用NCEP/NCAR再分析资料对中国按水汽输送划分的季风区进行验证。结果表明,末次盛冰期以来中国湖泊演化主要受千年尺度大气环流的驱动影响,在各个柯本气候区内没有明显的规律性。末次盛冰期以来,在季风区中国湖泊演化主要有早中全新世湖泊水位相对较高以及末次盛冰期和早全新世湖泊水位均较高2种演变规律;在东亚干旱区主要有中晚全新世期间湖泊水位相对较高以及末次盛冰期和中全新世湖泊水位均较高2种演变规律。本文为中国过去气候变化及湖泊演化机制研究提供新的证据,同时为人类全面认识末次盛冰期以来湖泊水位变化提供了新的视角。 相似文献
17.
川西北高原山地灾害垂直地带性 总被引：2，自引：0，他引：2
由于形成山地灾害的多种自然因素具有垂直地带性,尤其作为主要动力因素的水,超过一定高度后由液态成为固态,从而也造成了山地灾害的垂直地带性,从高到低可分为冰雪型、冻融型和流水(含地下水)型等三个山地灾害垂直带,高低两带之间主体界线在川西北高原地区为4900m和3500m。各带均有其特有的山地灾害,其中冰雪型山地灾害主要有冰崩、雪崩、冰面湖崩决等;冻融型山地灾害有冻融土流、冻融滑塌、冻融坍塌、融冻泥流、寒冻岩屑流和冰湖溃决等;流水型山地灾害有滑坡、崩塌、泥石流、山洪、泥石流坝和滑坡坝溃决等。认清这些灾害分布的垂直地带性,对于在相应地带进行资源开发和经济建设时,避免、减轻或妥善处治其危害具有重要的现实意义。 相似文献
18.
Huimin Yan Zhijun Yao Heqing Huang Dong Jiang Xiaohui Dong Rui Duan Yili Zhang 《地理学报(英文版)》2013,23(5):860-870
As they are products of glacier movement, the water body composition and water quality attributes of glacial lakes have distinct characteristics compared with inland lakes. Although satellite remote sensing provides an effective approach to monitor water quality, lack of in-situ measurement data on the status and environment surrounding glacial lakes presents a major constraint in relating satellite data to water quality indicators. This study presents findings of a preliminary investigation into water quality attributes of 3 glacial lakes in the Mount Qomolangma region. Suspended particulate matter （SPM）, light absorption attributes of phytoplankton, nonalgal particles （NAP）, and colored dissolved organic matter （CDOM） were measured. The suspended substance concentration varies markedly from 0-320 mg/L. This is considered to reflect differing stages of lake development. l-he chlorophyll concentra- tion is much lower than that found for inland lakes, as landscapes that surround these high altitude lakes have almost no vegetation growth. The phytoplankton and CDOM concentration depend on long-term stability of lake slopes. Given the lack of exogenous and endogenous inputs in the Qomolangma region, CDOM in glacial lakes is significantly lower than in inland lakes. These preliminary findings could support efforts to appraise estimates of water quality parameters using remotely sensed images. 相似文献
19.
E.A. Sagredo P.I. Moreno R. Villa-Martínez M.R. Kaplan P.W. Kubik C.R. Stern 《Geomorphology》2011,125(1):92-108
We present a new record from the Última Esperanza region (51°25’-52°25'S), southwestern Patagonia, to unravel the timing and structure of glacial fluctuations during the Last Glacial Termination (T1). This sector of southern South America represents the only windward-facing continental landmass in the Southern Hemisphere that intersects the core of the Southern Westerly Wind belt.Geomorphic, stratigraphic and geochronological evidence indicate the following stages during and since the Last Glacial Maximum (LGM): (i) deposition of prominent moraine complexes during at least two advances dated between ~ 39 and > 17.5 ka; (ii) development of an ice-dammed proglacial lake (glacial lake Puerto Consuelo) accompanying ice recession; (iii) active deposition of moraine complexes at intermediate positions followed by recession at ≥ 15.2 ka; (iv) lake level drop and subsequent stabilization between 15.2-12.8 ka; (v) a glacial readvance in glacial lake Puerto Consuelo between 14.8-12.8 ka; (vi) ice recession, stabilization, and lake level lowering between 12.8-10.3 ka; and (vii) glacial withdrawal and disappearance of glacial lake Puerto Consuelo prior to 10.3 ka. By comparing our results with the chronologies from neighboring regions we explore whether there was a consistent temporal/geographic pattern of glacial fluctuations during the LGM and T1, and examine their implications at regional, hemispheric, and global scales. The correspondence of these variations with key paleoclimate events recorded in the Southern and the Northern Hemispheres suggest a common forcing that, most likely, propagated through the atmosphere. Regional heterogeneities at millennial timescales probably reflect the influence of processes related to deep ocean circulation, and changes in the position/intensity of the Antarctic Polar Front and Southern Westerly Winds. 相似文献
20.
David R. Butler 《自然地理学》2013,34(1):86-98
Glacial, periglacial, and palynologic evidence from a small valley in the Lemhi Mountains of eastern Idaho indicates that an early Holocene cold climatic episode occurred there approximately 8,000 years ago. A small glacial moraine marks the farthest downvalley point of advance during a previously unrecognized glacial stade in the area. Periglacial ice wedges and involutions are preserved in buried sediments deposited during this same time. Pollen data extracted from these sediments suggest that an alpine steppe/tundra characterized the vegetational response to this period of early Holocene cold conditions. Other evidence from studies on the eastern Snake River Plain of Idaho corroborates these interpretations, suggesting a climatic reversal of regional importance. 相似文献