The lower paleolithic landscape of 'Ayoun Qedim,al‐Jafr Basin,Jordan

The 'Ayoun Qedim locality includes seven deflated Acheulian sites within and around a limestone box canyon, Juwit el Ghuweir, in the northern al‐Jafr Basin, Jordan. Survey of these sites identified dense scatters of Acheulian bifaces ( _ 1650) along with debris, cores, and reduction material from their production and maintenance. Although there is a clear Levallois component in the assemblages, reflecting a Late Acheulian occupation, strictly Middle and Upper Paleolithic sites are uncommon in this locality. Analysis of the geology and geomorphology of the northern al‐Jafr Basin indicates the area is strongly influenced by shallow subsurface groundwater flow and discharge, and Juwit el Ghuweir displays classic features of a canyon formed by groundwater seepage and sapping, except for the lack of a perennial spring within the modern canyon. The authors suggest that the extreme density of Lower Paleolithic material at 'Ayoun Qedim is associated with perennial groundwater discharge at Juwit el Ghuweir during the Middle Pleistocene and that the dearth of later Paleolithic material is attributable to the cessation of perennial spring discharge. The cause of the spring's cessation is unknown, but may have been related to local geomorphic factors, such as head migration of adjacent streams, or to more regional geomorphic factors, such as the lowering of theregional water table in the area of al‐Jafr Basin. © 2007 Wiley Periodicals, Inc.     

地貌成因中力的耦合律

本文提出了“地貌形成中力的耦合律”,认为地貌是在动力和反动力作用下形成、发展和演化。演化过程中,动力和反动力在偶合点处互相激活产生了循环前进式的多层次的地貌演化模式。     

Geomorphic Effects of Monsoon Floods on Indian Rivers

The southwest summer monsoon contributesthe bulk of India's rainfall. Consequently,almost all the geomorphic work by the rivers is carried out during the monsoonseason in general and the monsoon floods in particular. Indian rivers arecharacterized by high average flood discharges and large temporal variability. Thereis also significant spatial variation in the magnitude, frequency and power of floods, on account of regional variations in monsoon rainfall, basin characteristics andchannel geometry. As a result, the channel responses and the geomorphic effects also varyspatially. This paper describes the hydrological and geomorphological aspects, as well asthe geomorphic effects of monsoon floods in the Indian rivers. The geomorphic effects of floods are most impressive only in certainareas – the Himalaya, the Thar Desert, and the Indus-Ganga-Brahmaputra Plains. There are numerous instances of flood-induced changes in the channel dimension,position and pattern in these areas. In the Ganga-Brahmaputra Plains, the annualfloods appear to be geomorphologically more effective than the occasional large floods.In comparison, the rivers of the Indian Peninsula are, by and large, stable and thegeomorphic effects of floods are modest. Only large-magnitude floods that occur at aninterval of several years to decades are competent to modify the channel morphology in asignificant way. A synthesis of the various case studies available from the Indianregion indicates that often the absolute magnitude of a flood is not as important withrespect to the geomorphic effects as the flow stress and competence.     

Geomorphic and structural evidences of neotectonic activity in the Sub-Himalayan belt of Nahan Salient,NW India

Neotectonism in the Sub-Himalayan belt is not new. Moreover, the word ‘Sub-Himalaya’ is almost synonymous with ‘neotectonic activity’. In the present paper, we report some of the most convincing geomorphic and structural evidences of neotectonic activity from the Sub-Himalayan belt in the Nahan Salient. The geomorphic evidences mainly include the four geomorphic surfaces identified from the transverse topographic profiles drawn parallel to the Himalayan front. These surfaces are commonly covered with terrace deposits that are tilted as well as faulted at a number of places. A number of faults, directly observable in the field, are normal in nature and they are oriented at high angles to the Himalayan Frontal Thrust (HFT). These faults are similar to the E-W extension in southern Tibet in response to the oblique convergence of India at ∼N20°E in the NW Himalaya. They are attributable to the kinematics of neotectonic compression along the HFT, the frontal ramp-oblique ramp-frontal ramp geometry of the thrust fault and related adjustments.     

Geomorphic investigation of the terrebonne marsh,louisiana: Foundation for cultural resource surveys

A geomorphic investigation of Terrebonne Marsh in south-central Louisiana was conducted to establish a framework for subsequent cultural resource investigations. the investigation consisted of an initial phase of detailed geomorphic mapping, subsequent field investigations, sedimentological, biostratigraphical, and chronological analyses of field samples, and paleoenvironmental reconstruction of the area. the investigation substantiated and refined previous interpretations of the progradation of three Mississippi River deltas through the area. the earliest known Holocene delta, the Maringouin, was probably active in the area from 7000 to 6000 years before present (YBP). the Teche delta prograded through the area from 4500 to 3500 YBP. From approximately 2000 to 1000 YBP the Lafourche delta partially buried the Teche delta. the periods of approximately 6000-4500, 3500-2000, and 1000 YBP to present were characterized by deltaic subsidence and erosion. Distributary natural levees and beach ridges appear to be sites of major cultural focus in Terrebonne Marsh. Due to high rates of subsidence, older cultural components are either buried or disturbed by erosion.     

太行山中段羊角玄武岩形态特征及其地质意义

太行山中段左权羊角镇发育新生代玄武岩, 记录了太行山新生代以来的构造隆升事件。在详细的野外调查和研究的基础上, 通过与玄武岩发育相关的地貌面及其上的地层特征分析, 初步确定该玄武岩是上新世末期到早更新世初期的喷发产物, 初步揭示了太行山中段区域上晚上新世以来地貌发育历史, 主要存在6次构造隆升与剥蚀期: 在唐县期宽谷面形成的基础上, 于上新世晚期存在一次隆升和一次稳定侵蚀期, 并侵蚀形成“U”形谷; 早更新世初, 玄武岩开始间歇性喷发, 同时发生以西武家坪为中心的地区上拱, “U”形谷为玄武岩充填, 之后经剥蚀堆积形成第四级阶地面; 早更新世末, 该区再次发生隆升, 并形成第四级阶地; 中更新世末, 该区发生隆升, 形成第三级阶地; 晚更新世以来, 太行山中段又连续发生两次抬升, 从而在玄武岩体上形成了4级阶地, 形成太行山现今地貌。研究同时表明, 太行山中段上新世晚期以来的隆升主要发生于上新世末到早更新世时期。这一认识为探讨太行山中段晚上新世以来的构造隆升提供了具体证据。     

重庆城市地貌研究的设计与实践

介绍了重庆城市地貌研究的设计与实践。认为:宜以城市的建成区和边缘区为重点研究区,并根据城市地貌环境的特点来进行设计。从以下几个方面介绍了重庆城市地貌研究的实践:(1)地貌环境对城市的影响;(2)城市对地貌环境的影响;(3)城市地貌灾害;(4)城市地貌分类与制图;(5)城市地貌环境的质量评价。     

Morphotectonic evolution of the New Caledonia ridge (Pacific Southwest) from post-obduction tectonosedimentary record

The tectonostratigraphic and geomorphic study of two post-obduction fluvial sedimentary systems on mainland New Caledonia and imaged offshore on seismic reflection lines provides a new perspective on the post-orogenic evolution of the New Caledonia ridge. Relations between sedimentary sequence boundaries, erosion surfaces and faults, both on land and on offshore seismic reflection profiles indicate that an episode of extensional tectonics initiated in the Early Neogene led to the disruption and collapse of the island landsurface previously shaped during a Latest Oligocene phase of planation. Microtectonic analysis further suggests early slip on the normal faults was associated with ridge-normal extension. A later set of faults accompanied ridge-parallel to ridge-oblique extension that is interpreted to result from a shift toward a transtensional regime driven by the initiation of east-verging subduction of the Australian plate beneath the Pacific plate starting at least in the late Mid-Miocene.     

松辽盆地南部喜山期构造演化与铀成矿

分析了松辽盆地在喜山旋回中所处的应力场、喜山期构造运动及所产生的地貌环境,认为喜山期构造运动为松辽盆地砂岩型铀矿形成创造了有利的构造地貌条件,主要成矿时间为始新世、上新世。松辽盆地南部盆缘剥蚀天窗区构造发育,成矿作用明显,是寻找地浸砂岩型铀矿的有利地段。     

Some regional indicators of the Tertiary–Quaternary geodynamics in the paleocoastal part of the Bengal basin (India)

Sedimentary processes in the paleocoastal part of the Bengal basin that occured in the Tertiary and Quaternary have been addressed. Three indicators were used: sedimentary bedding forms, microstructure of the sediment, and trace fossils. Various forms of sedimentary structures developed under the influence of dynamic geomorphic processes in the study area in the Quaternary. The microstructure analysis of the sedimentary materials was made by two methods: microphotography and Digital Color Analysis (DCA). The microstructure analysis shows that the geomorphic process remained very dynamic in the Quaternary, influencing the form, thickness, and mineral composition of the sediment strata. The enrichment of the sediments in heavy minerals evidences either oscillating or combined flow sedimentation, while under stable conditions light-mineral deposition took place. The digital data of microfabric study by the DCA method also show that larger particles deposited in the oscillating or high-flow environment and evidence a greater amount of heavy minerals like ferruginous materials. Trace fossils found in the sediments of this area also strongly support the concept that the environment remained dynamic during the Tertiary and Quaternary. The Late Tertiary deposition shows that, during these periods, the sediments were transported from tide-dominated marine coast with low flow energy, which is typical of hot and humid conditions. From Late Tertiary to Early Quaternary, the macrotidal coast became mesotidal (wave-dominated). The second phase is the Middle Pleistocene, when the environment was stable, favoring the continuous deposition of finer particles under low- to medium-flow energy conditions. The third phase, the Recent, is marked by the shoreline shift and modification of the environment. In the Early–Middle Holocene, the shoreline started to shift, which modified the geomorphic conditions of this place from coastal to estuarine and, finally, inland fluvial.     

Scale of relief growth in the forearc of the Andes of Northern Chile (Arica latitude, 18°S)

The stream profiles of rivers of northern Chile reveal two graded segments separated by 20‐km‐long knickzones. Their formation was initiated in the Late Miocene in response to surface uplift of the western flank of the Altiplano. This phase of uplift that was coeval with the shift of deformation from the Altiplano to the sub‐Andean zone caused relief to grow at the scale of the whole drainage basin. Above and beneath these knickzones, the presence of braided channels and the absence of erosion on adjacent pediplains suggest no substantial modification in the local relief. The knickzones, however, show bedrock channels, and fluvial dissection rates have exceeded erosion rates on adjacent pediplains by two orders of magnitudes. Hence, the data imply that the only geomorphic recorders of relief growth are the knickzones that currently transpose the effects of the Late Miocene phase of surface uplift from the coast to the Altiplano.     

Geologic constraints on the Harappa archaeological site,Punjab Province,Pakistan

The geologic setting of an urban environment affects the development of that particular urban culture. Human activities can involve devegetation, soil loosening, soil‐water and ground‐water changes, soil erosion, and changes in surface‐water hydrology. This article focuses on how the geologic resources and history of the Punjab region have greatly influenced the cultural development of the Bronze Age city of Harappa, located in northeast Pakistan. Archaeological deposits at this site date between at least 3300 B.C. and 1700 B.C. A geologic and geomorphic framework is provided which presents the relationships of the ancient Harappans with their local and regional environment, with these geologic processes affecting both the initial settlement and development of this ancient urban center. Buried soil elevation data, mapped soil distributions, and geomorphic models are used to construct an approximation of the preoccupation paleotopography beneath this site. © 2000 John Wiley & Sons, Inc.     

乌兹别克中卡兹库姆地貌特征对砂岩型铀矿赋存的制约

为了理清地形地貌对砂岩型铀矿赋存的制约作用,基于GIS技术,利用DEM影像数据提取了中卡兹库姆地区高程、坡度、坡向、地形起伏度及条带剖面等各类地貌因子,并与研究区探明的砂岩型铀矿进行空间关联与定量化分析。研究结果表明砂岩型铀矿赋存的有利地形地貌条件:高程为100~400 m、坡度为0°~5°、地形起伏度为10~35 m、亚流域面积-高程积分值为0.3~0.6;中卡兹库姆地区存在4个较为明显的夷平面,高程分别为:Ⅰ级2 200 m,Ⅱ级1 600 m,Ⅲ级1 100 m,Ⅳ级330~400 m,砂岩型铀矿发育于Ⅳ级夷平面附近;砂岩型铀矿集中于低海拔和低地形起伏度的地区,二者可作为砂岩型铀矿找矿预测的主要参考因素。最后根据地貌因子圈定了中卡兹库姆地区砂岩型铀矿赋存的有利区域,为该区砂岩型铀矿找矿提供依据。     

Fluvial processes and settlement in arid environments

The impact of fluvial geomorphic processes on settlement in deserts is tie d to two conflicting factors: the extreme rarity of geomorphic events on the one hand, and the violence of the geomorphic forces coupled with a minimal resistance to erosion on the other.The unique character of desert floods calls for a careful geomorphic evaluation in the siting of settlements and transportation facilities. On the beneficial sid e, the geomorphic processes involved enable, under some conditions, the local exploitation of floodwaters which percolate in the alluvium of the upper tributaries, as well as the utilization of the hydraulic geometry for estimating discharge characteristics.On a larger scale, human interference often disrupts the delicate quasi-equilbrium between erosion and sedimentation in deserts. Although our poor understanding of many aspects of the mechanism of response makes it difficult to separate the effects from those of climatic changes, enough information is available to document the detrimental effect of inconsiderate management on both the regional and local levels.     

基于地貌信息熵的天山公路冰川泥石流危险性评价

冰川泥石流广泛分布于我国西部地区,特殊的地貌条件对泥石流的发育有着重要影响。地貌信息熵理论是量化地貌发育阶段的指标,针对冰川地貌条件,探讨了地貌信息熵理论在冰川地貌条件下的应用,并提出了相应的修正系数。选取天山公路沿线13条泥石流沟,基于ArcGIS平台,进行了危险性评价。结果表明,修正后的地貌信息熵值能较好地判断冰川泥石流的危险程度。     

金沙江金坪子堆积体形成过程对青藏高原东缘构造、气候的响应

金坪子堆积体位于金沙江河谷之中,处在＂康滇地轴＂的中部,类似一个大滑坡体。通过对金坪子堆积体的数字高程模型（DEM）、12个钻孔、1个平硐和1个竖井资料的分析,以及实地调查,对金坪子堆积体的沉积物进行沉积学、年代学和岩石地层学等多学科的研究。金坪子堆积体由12层不同的沉积物和8个地貌单位组成,其中1～9层为古金沙江河流...     

Broad Timescale Forcing and Geomorphic Mediation of Tidal Marsh Flow and Temperature Dynamics

Tidal marsh functions are driven by interactions between tides, landscape morphology, and emergent vegetation. Less often considered are the diurnal pattern of tide extremes and seasonal variation of solar insolation in the mix of tidal marsh driver interactions. This work demonstrates how high-frequency hydroperiod and water temperature variability emerges from disparate timescale interactions between tidal marsh morphology, tidal harmonics, and meteorology in the San Francisco Estuary. We compare the tidal and residual flow and temperature response of neighboring tidal sloughs, one possessing natural tidal marsh morphology, and one that is modified for water control. We show that the natural tidal marsh is tuned to lunar phase and produces tidal and fortnight water temperature variability through interacting tide, meteorology, and geomorphic linkages. In contrast, temperature variability is dampened in the modified slough where overbank marsh plain connection is severed by levees. Despite geomorphic differences, a key finding is that both sloughs are heat sinks in summer by latent heat flux-driven residual upstream water advection and sensible and long-wave heat transfer. The precession of a 335-year tidal harmonic assures that these dynamics will shift in the future. Water temperature regulation appears to be a key function of natural tidal sloughs that depends critically on geomorphic mediation. We investigate approaches to untangling the relative influence of sun versus tide on residual water and temperature transport as a function of system morphology. The findings of this study likely have ecological consequences and suggest physical process metrics for tidal marsh restoration performance.     

基于地貌参数法的无资料地区洪水预报研究

为了探索无资料流域的洪水预报问题,以改进的HBV模型为例,介绍应用地貌参数法推求无资料地区模型参数的方法。并利用武江流域实测50场雨洪资料,对改进的HBV模型进行率定,在参数达到较好的模拟效果后,与流域的地貌参数建立相关关系,然后利用所建立的相关关系及武江支流田头水和韩江支流丰良河的地貌参数,推求模型参数,最后用田头水和丰良河各50场洪水进行验证,取得了较好效果。     

Geomorphic evidence for Holocene glacial advances and sea level fluctuations on eastern Vestfirðir, northwest Iceland

New geomorphic and chronological data of Holocene advances of the Drangajökull Ice Cap, located on eastern Vestfirðir, northwest Iceland, are presented. At least two glacial advances and two transgressions during the Holocene are interpreted from moraines and raised beach deposits, respectively. Geomorphic evidence is concentrated in the three valleys adjacent to the modern outlet glaciers of the Drangajökull Ice Cap: Kaldalónsjökull, Leirufjarðarjökull, and Reykjarfjarðarjökull. The valley surrounding Kaldalónsjökull contains a vegetated Holocene moraine with a minimum radiocarbon age of ∼2600 cal. yr BP, which provides geomorphic evidence for Neoglacial activity on eastern Vestfirðir. The second extensive Holocene glacial advance on eastern Vestfirðir occurred during the Little Ice Age, and moraines associated with this advance are present in all three outlet glacier valleys. The Neoglacial advance is the most extensive ice advance on eastern Vestfirðir. Raised beaches parallel to the coastlines of Ísafjarðardjúp and Jökulfirðir, at an elevation of approximately 5 m a.s.l., suggest a minor transgression at ∼3000 cal. yr BP based on radiocarbon ages of shells. A minor transgression of 0.3–0.5 m a.s.l. is associated with the timing of the Little Ice Age advance. Correlation of geomorphic events with sediment proxy records facilitates distinguishing local perturbations from regional North Atlantic climate signals. This study supports regional interpretations of climatic instability during the Holocene.     

Characteristics of a paleosol and its implication for the Critical Zone development,Rocky Mountain Front Range of Colorado,USA

Activity and stability phases as well as geomorphic processes within the Critical Zone are well known. Erosion and deposition of sediments represent activity; soils represent geomorphic stability phases. Data are presented from a 4 m deep sediment section that was dated by luminescence techniques. Upslope erosion and resulting sedimentation started in the late Pleistocene around 18 ka until 12 ka. Conditions at the study site then changed, which led to the formation of a well-developed soil. Radiocarbon dating of the organic matter yielded ages between 8552 and 8995 cal. BP. From roughly 6.2 to 5.4 ka another activity phase accompanied by according sediment deposition buried the soil and a new soil, a Cambisol, was formed at the surface. The buried soil is a strongly developed Luvisol. The black colors in the upper part of the buried soil are not the result of pedogenic accumulation of normal organic matter within an A-horizon. Nuclear magnetic resonance spectroscopy clearly documents the high amount of aromatic components (charcoal), which is responsible for the dark color. This indicates severe burning events at the site and the smaller charcoal dust (black carbon) was transported to deeper parts of the profile during the process of clay translocation.