LATE QUATERNARY GEOMORPHIC HISTORY OF LOWER HIGHLAND CREEK,WIND CAVE NATIONAL PARK,SOUTH DAKOTA

Mapping of late Quaternary geomorphic surfaces, and analysis of the soils and sediments buried within them, provides evidence for the history of a small study area within the Red Valley physiographic zone, Black Hills, South Dakota. Geomorphic thresholds for this grassland system are correlated with periods of major climatic change. Well-developed soils dating to the late Pleistocene and early Holocene (14,000 to 9000 yr B.P.) suggest more mesic conditions and geomorphic stability. A mid-Holocene Altithermal (ca. 8000 to 4500 yr B.P.) denudation almost completely stripped the landscape of earlier Holocene sediments and soils. A prolonged, mid-Holocene (ca. 4500 to 3600 yr B.P.) mesic period of landscape stability and soil development followed, but was abruptly terminated around 3600 yr BP. Late Holocene conditions approached stability about 1200 yr BP. After this time, alluvial terrace surfaces remained stable, while alluvial fans experienced periods of stability punctuated by midslope aggradation.     

Pre-farming environment and OSL chronology in the Negev Highlands,Israel

The ancient agriculture in the southern Levant is very much dependant on the interaction between the geological and geomorphological characteristics of the desert environment and the arid climatic conditions. Field observations and luminescence dating in the Negev Highlands, southern Israel, indicate that deposition of fluvio-loess sediments occurred mainly during the late Pleistocene glacial period. These sediments, which were transformed into loessy soil, support a high natural biomass and have an agricultural potential. Major soil erosion started after 27 ka, exposing bedrock, increasing runoff and erosion. These feedback processes were intensified during the Holocene. Since the mid Holocene, the co-existence of soil and runoff created a unique setup which enabled the establishment of desert agriculture in the southern Levant, based on runoff-harvesting techniques. Extensive construction of stone terrace walls on top of diachronous middle–late Holocene alluvial units in the less degraded valleys led to the deposition of the anthropogenic unit, consisting of fine grained re-deposited loess as a by-product of the flood irrigation. This process contributed to soil conservation and counteracted the continuous natural soil erosion and desertification. The ability to practice desert agriculture is still preserved in the southern Levant, and historic climate changes are not required to explain the rise and fall of the great farming cultures.     

黄土高原侵蚀环境与侵蚀速率的初步研究

黄土高原的侵蚀是一个地质过程.晚更新世以前高原已经过三个大的侵蚀堆积旋迥,主要沟谷系统和黄土地貌的塬梁峁格局已经形成.全新世以来黄土的堆积逐渐减缓,而侵蚀则进入新的发展时期.在自然因素和人类活动的共同作用下,土壤侵蚀加剧.根据侵蚀一堆积相关原理,利用黄河下游不同时期发育的冲积扇沉积模式,估算了全新世以来自然侵蚀速牵为7.9%,由于人类活动而引起的加速侵蚀的速率逐渐递增,至今已达到25%.     

舟山群岛北部的地理环境与黄棕壤的形成——兼论新构造运动影响及红壤带的北界问题

舟山群岛北部历来划属红壤带,但良好发育且分布最广的是黄棕壤,因其多种性状与气候等环境酷似南京下蜀黄土上的典型黄棕壤。黄棕壤上无红化迹象,不能以下部有酸性古红土而将本区误定为红壤带。第四纪以来地球上有过多次气候波动,使红壤带的北界南北摆动。红壤带在目前不一定有红壤化作用在进行,它仅表示为红壤相对集中的地带。本文还讨论了该黄棕壤形成过程中,新构造运动在多方面的重要影响。     

Soil-stratigraphic techniques in the study of soil and landform evolution across the Southern Alps, New Zealand

The Southern Alps lie along the convergent Pacific-Indian plate boundary. Geomorphically distinct eastern, axial and western regions reflect the east-west gradient in tectonic uplift (1 to 10 mm a⁻¹) and precipitation (600 to 10,000 mm a⁻¹). The eastern region is divided into front-ange and basin-and-range subregions. Soil-sequence studies on terraces established temporal contrasts in pedogenesis within and between eastern and western regions encompassing Entisols, Inceptisols and Spodosols. On Late Pleistocene and early Holocene terraces Dystrochrepts are persistent soils in the eastern region and Aquods in the western region. These soil sequences are used in the interpretation of relative soil age, stratigraphy and erosion history in hill and mountain drainage basins of the eastern and western regions. In the subhumid to humid eastern front-range subregion, simple soil forms occur as catenary sequences, and there is little evidence of erosion following the destruction of forests in the last millenium. Mollisols are dominant in the subhumid, and Dystrochrepts in humid areas, respectively. Soil-debris mantle regoliths date from the early Holocene and are still developing on slopes. The soil pattern on mountain slopes in the humid, eastern basin-and-range subregion is a complex array of simple, eroded, composite and compound soils. This pattern has resulted from erosion following forest destruction within the last millenium. The oldest surface or buried forest soils are Dystrochrepts dating from the Late Pleistocene to early Holocene. Wind erosion of these low-fertility soils contributes to the loessial sediments in which younger soils have formed. In the western region, soil patterns and soil stratigraphy indicate continous instability with a complex pattern of highly leached, shallow Orthents and bedrock outcrops on slopes. The soils are eroded from slopes within 2 ka. These contrasts in soil development and erosion periodicity in the eastern and western regions of the Southern Alps parallel the east-west contrasts in erosion rates of ca. 1–10 mm a⁻¹.     

Contrasting soils and landscapes of the Piedmont and Coastal Plain, eastern United States

The Piedmont and Coastal Plain physiographic provinces comprise 80 percent of the Atlantic Coastal states from New Jersey to Georgia. The provinces are climatically similar. The soil moisture regime is udic. The soil temperature regime is typically thermic from Virginia through Georgia, although it is mesic at altitudes above 400 m in Georgia and above 320 m in Virginia. The soil temperature regime is mesic for the Piedmont and Coastal Plain from Maryland through New Jersey. The tightly folded, structurally complex crystalline rocks of the Piedmont and the gently dipping “layer-cake” clastic sedimentary rocks and sediments of the Coastal Plain respond differently to weathering, pedogenesis, and erosion. The different responses result in two physiographically contrasting terrains; each has distinctive near-surface hydrology, regolith, drainage morphology, and morphometry.The Piedmont is predominantly an erosional terrain. Interfluves are as narrow as 0.5 to 2 km, and are convex upward. Valleys are as narrow as 0.1 to 0.5 km and generally V-shaped in cross section. Alluvial terraces are rare and discontinuous. Soils in the Piedmont are typically less than 1 m thick, have less sand and more clay than Coastal Plain soils, and generally have not developed sandy epipedons. Infiltration rates for Piedmont soils are low at 6–15 cm/h. The soil/saprolite, soil/rock, and saprolite/rock boundaries are distinct (can be placed within 10 cm) and are characterized by ponding and/or lateral movement of water. Water movement through soil into saprolite, and from saprolite into rock, is along joints, foliation, bedding planes and faults. Soils and isotopic data indicate residence times consistent with a Pleistocene age for most Piedmont soils.The Coastal Plain is both an erosional and a constructional terrain. Interfluves commonly are broader than 2 km and are flat. Valleys are commonly as wide as 1 km to greater than 10 km, and contain numerous alluvial and estuarine terrace sequences that can be correlated along valleys for tens of kilometers. Coastal Plain soils are typically as thick as 2 to 8 m, have high sand content throughout, and have sandy epipedons. These epipedons consist of both A and E horizons and are 1 to 4 m thick. In Coastal Plain soils, the boundaries are transitional between the solum and the underlying parent material and between weathered and unweathered parent material. Infiltration rates for Coastal Plain soils are typically higher at 13–28 cm/h, than are those for Piedmont soils. Indeed, for unconsolidated quartz sand, rates may exceed 50 cm/h. Water moves directly from the soil into the parent material through intergranularpores with only minor channelization along macropores, joints, and fractures. The comparatively high infiltration capacity results in relatively low surface runoff, and correspondingly less erosion than on the Piedmont uplands.Due to differences in Piedmont and Coastal Plain erosion rates, topographic inversion is common along the Fall Zone; surfaces on Cenozoic sedimentary deposits of the Coastal Plain are higher than erosional surfaces on regolith weathered from late Precambrian to early Paleozoic crystalline rocks of the Piedmont. Isotopic, paleontologic, and soil data indicate that Coastal Plain surficial deposits are post-middle Miocene to Holocene in age, but most are from 5 to 2 Ma. Thus, the relatively uneroded surfaces comprise a Pliocene landscape. In the eastern third of the Coastal Plain, deposits that are less than 3.5 Ma include alluvial terraces, marine terraces and barrier/back-barrier complexes as morphostratigraphic units that cover thousands of square kilometers. Isotopic and soil data indicate that eastern Piedmont soils range from late Pliocene to Pleistocene in age, but are predominantly less than 2 Ma old. Thus, the eroded uplands of the Piedmont “peneplain” comprise a Pleistocene landscape.     

CHAOTIC EVOLUTION OF SOME COASTAL PLAIN SOILS

Nonlinear dynamical systems (NDS) models of soil systems suggest that soil evolution may be potentially chaotic, and thus sensitive to initial conditions and to small perturbations. Chaos implies that the diversity of the soil cover should increase over time. This hypothesis was tested by comparing the diversity of soil types on either side of the Suffolk Scarp on the lower coastal plain of North Carolina. While parent material and other soil-forming factors at the two sites are similar, the Pamlico Terrace east of the scarp is late Pleistocene and the Talbot Terrace west of the scarp is middle to late Pleistocene and at least twice as old. A soil system model based on vertical clay distribution and textural differentiation is introduced to account for the major factors that lead to differentiation of soil series in the study area. The model is unstable and potentially chaotic and, like more general models, predicts that even where all other soil-forming factors are similar, the diversity and spatial variability of soils should be greater on older soil landscapes. Soil series were identified along 0.5 km transects on either side of the Suffolk Scarp in Craven County. Only one soil series was identified on the Pamlico site, while the Talbot transect included at least seven distinct soil series. The dramatically higher variability of the soil cover on the older landscape is predicted by the model and provides field evidence for chaotic pedogenesis. [Key words: chaos theory, soils, Pleistocene, North Carolina].     

Climatic influences on Holocene variations in soil erosion rates on a small hill in the Mojave Desert

A detailed study of a small hill in NE Mojave Desert in eastern California was conducted to elucidate the effect of climate on the variations in soil erosion rates through Holocene. Field surveys and sampling were carried out to obtain information on topography, geomorphology, soil and vegetation conditions, seismic refraction, sediment deposition, and hillslope processes. Integration of this information allowed reconstruction of the hill topography at the end of the Pleistocene, deduction of the evolution of the hill from the end of the Pleistocene to the present, and estimation of total soil losses resulting from various hillslope processes. The estimates are consistent with the premise that early Holocene climate change resulted in vegetation change, soil destabilization, and topographic roughening. Current, very slow, hillslope transport rates (e.g., 5 mm ky⁻¹ by rodent burrowing, a presently important transport form) appear inconsistent with the inferred total soil loss rate (31 mm ky⁻¹). Packrat midden studies imply that the NE Mojave Desert experienced enhanced monsoonal precipitation in the early Holocene, presumably accentuating soil loss. Water erosion on one slope of the hill was simulated using Water Erosion Prediction Project (WEPP), a process-based erosion model, using 4 and 6 ky of precipitation input compatible with an appropriate monsoonal climate and the present climate, respectively. The WEPP-predicted soil losses for the chosen slope were compatible with inferred soil losses. Identification of two time periods within the Holocene with distinct erosion characteristics may provide new insight into the current state of Mojave Desert landform evolution.     

东北典型黑土区气候 、 地貌演化与黑土发育关系

通过野外实地调查,利用地层学方法结合孢粉分析结果,研究了黑土区地层地貌的发育历史、地层序列以及古气候变化,重建黑土、黑钙土的发育历史及发育所需的地貌、气候条件。结果表明,黑土从温暖湿润的晚更新世早期便开始在嫩江的二、三级阶地上发育,而黑钙土则从全新世初开始在嫩江的一级阶地上发育,这时气候处于暖干期,且一级阶地地势较低,水位相对较高,容易接受上方高地淋洗下来的钙,从而在土壤中形成比较典型的淀积层。可见,地貌条件及气候因素对黑土、黑钙土的形成发育起到至关重要的作用。研究结果为黑土区的水土保持及土壤改良研究提供理论基础,同时为正确评估黑土层的侵蚀速率及制订合理的改良措施提供科学的参考。     

Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area.This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating.In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations.Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.     

金衢盆地退化红砂土在不同利用方式下肥力逆转特征

以浙江省金衢盆地为例 ,探讨了我国南方山间盆地广泛分布的退化红砂土的特征 ,研究了退化红砂土在人为参与下土壤肥力的逆转及其与利用方式的关系 ,分析了各种利用方式下红砂土肥力性质的演变特征。     

An early Holocene erosion phase on the loess tablelands in the southern Loess Plateau of China

A Holocene loess profile to the west of Xi'an China was studied multi-disciplinarily to investigate the relationships between soil erosion and monsoonal climatic change. The proxy data obtained from this aeolian loess and palaeosol sequence indicate large-scale variations of climate in the southern Loess Plateau since the last glaciation. A rainwash bed, indicative of a wetter climate, excessive runoff and erosion on the loess tablelands, was identified relating to the early Holocene before the onset of the “climatic optimum”. This is synchronous with the early Holocene physiographic erosional stage identified in the valleys in North China. It means that severe erosion took place when the region was undergoing climatic amelioration during the early Holocene. The evidence presented in this paper shows that the erosion occurred as a regional response to a monsoonal climatic shift in the southern Loess Plateau. During the last glaciation, prior to the erosion phase, the land surface on the tablelands had been largely stable except for the rapid accumulation of aeolian dust and the resultant increase in its elevation. Relatively slow dust accumulation and intensive bio-pedogenesis responding to the Holocene “climatic optimum” followed the erosion phase. The loess tablelands were most vulnerable to erosion during the large-scale monsoonal climatic shift from dry-cold glacial to humid-warm post-glacial conditions in the southern Loess Plateau.     

Land degradation in north-western Jordan: causes and processes

Improper farming practices, overgrazing, the conversion of rangelands to croplands in marginal areas and uncontrolled expansion of urban and rural settlement at the cost of cultivable land are among the major causes of land degradation in north-western Jordan. The purpose of this study was to discuss the major causes of land degradation in the area.Six sites receiving different amounts of annual precipitation and with different vegetation types were selected to represent the major agricultural areas in north-western Jordan. The major soil properties that can be linked to land degradation were studied.Desertification in north-western Jordan is taking place through loss of soil fertility and productivity, overgrazing and water and wind erosion. Erosion by wind and water is considered the major cause of land degradation in the area. The soils contain little organic matter and their alkaline reactions reduce the availability of phosphorous and macronutrients and consequently lead to very low crop yields.     

云南省几种土壤的发生特性与发育环境演变

本文从孢粉组成及石英砂表面形态角度研究了滇东南几种土壤的沉积环境及其演变，并研究了土壤粘粒矿物特性及化学组成特点。结果表明，土壤除受着目前成土因子作用外，沉积古环境及其演变对土壤发育特性及矿物学化学组成也有深刻的影响。     

黄河中游土壤侵蚀与下游古河道三角洲演化的过程响应

根据黄土高原土壤侵蚀的周期特点，结合华北平原古河道，古三角洲的演化过程，应用泥沙输移的过程响应,分析了晚更新世以来黄河中游黄土高原土壤侵蚀与下游古河道，三角洲演化的关系，在人类历史之前，黄土高原土壤侵蚀基本上遵循自在生态环境演化规律，强裂侵蚀期发生在干冷向湿湿气候转化的过渡期，在强裂侵蚀的初期是古道形成期，强烈侵蚀期发生在干冷向温湿气候转化的过渡期，在强裂侵蚀的期是古河道形成期，强烈侵蚀的外营力迭加了人为作用，黄河下游河游泳以改道，三角洲横向扩展发生在强烈侵蚀的衰退期，人类历史时期，土壤侵蚀的外营力迭加了人为作用，破坏了地质历史时期的规律性，土壤侵蚀强度越来越强，基本上按照旱涝变化频率而演化，干冷期降雨不均匀系数增加，土训侵蚀加重，径流量较少，河床以淤积为主，是古河道形成期，正常年黄河泥少输移比接近于一，是三角洲进积期，温湿期降雨量增加，径流量加大，下游河流改道，三角洲横向发展。     

粤西河流阶地的分布与特征

依据广东西部超过18条河流、39处河流阶地、至少35个14C、热释光的冲积层测龄数据等情况,可知粤西最多有4级河流阶地(不包括湛江组和北海组阶地);多数河流最高阶地靠近现代主河床分布,深切曲流中有河流阶地,反映近数十万年来河床改道不大;西江在封开有广东高度最高(76 m)的河流阶地,而广东高度最高的地下河阶地是111 m,大致显示出地面与地下剥蚀强度的差异;通常山区河流长度越大,河漫滩和河流阶地的高度越大,河流阶地的级数和级别也常增加;在河流上游的下段和中游的上段,河流阶地的高度最大且级数也最多;在晚更新世之前与后,河谷中下游地区的新构造运动趋势由上升变为稳定或沉降;连滩盆地是广东全新世构造沉降最典型的山间盆地。     

SOIL CATENAS,TROPICAL DEFORESTATION,AND ANCIENT AND CONTEMPORARY SOIL EROSION IN THE PETéN,GUATEMALA

The Petexbatún region of Guatemala's Petén tropical forest lowlands has been largely deforested since the early 1980s as landless peasants have turned even national parks into milpas. The soils of these tropical forest, karst landscapes are known mainly from small-scale maps and archaeological investigations. This paper investigates soil catenas and natural slope processes from the region's last virgin tropical forests and compares these with catenas and processes on slashed and burned slopes. Soils were sampled and analyzed for physical, fertility, and taxonomic measures. This primary forest toposequence forms a typical downward translocation catena, with the thickest soils (>200 cm) in depressions, the thinnest soils on shoulder slopes, and moderately thin soils on the crests and backslopes. Most crest and sloping soils are Lithic Rendolls and contain simple O-A-C horizon sequences, and most soils have little sign of either eluviation or illuviation. A few deeper soils on the slopes are Vertic Rendolls and have moderate slick-ensides, whereas footslopes and seasonally drained depressions are well developed Vertisols. The primary forest soil catena was compared with two slash-and-burn milpas, one with comparable slopes and one with steeper slopes. The comparably sloped milpa had soil thicknesses that were 7.9 to 13.8 cm thinner, truncated horizons, and physical evidence of erosion. The steeper milpa had soil thicknesses that were 11.1 to 18.2 cm thinner and also had truncated horizons and physical evidence of erosion. Where ancient Maya terraces (Late Classic, ca. 550 to 830 A.D.) are present in the slash-and-burn landscape, an average of 25 to 46.5 cm soil remain upslope and 9.3 to 16.1 cm remain downslope. The findings show high soil truncation rates and erosion to bedrock in a decade in one place, though ancient Maya terraces are still holding 2.7 to 3.6 times more soil than the surrounding hillslopes. Despite high modern erosion, lake sediments show surprisingly low soil losses in the Maya Late Classic during the period of the most intensive land use. In contrast, studies at Copán, Honduras and in the northern Petén, where terrace evidence is scant, show high rates of erosion during this period. [Key words: soil catenas, tropical deforestation, milpa, soil erosion, Maya Lowlands.]     

A pleistocene origin for shore platforms along the Northern Illawarra Coast,New South Wales

This paper examines the composition, structure and age of clastic deposits situated behind shore platforms at Austinmer and Coledale on the northern Illawarra coast, New South Wales. Our results support earlier chronological evidence of a Pleistocene history for shore platforms along the Illawarra coast. The size and fabric of sediments within these deposits indicate rapid, high‐energy deposition of bedrock eroded from platforms adjacent to the deposits. The elevations of the deposits above the modern shoreline suggest higher sea levels or higher wave energy gradients than presently occurs across these platforms. Dating of sediments within these deposits using ¹⁴C, AAR and TL techniques indicates Late Pleistocene and Late Holocene erosion of the shore platforms. Platform development was initiated before the Last Interglacial as correlative sediments lie atop relict platform surfaces landward of the modern platforms.     

Anthropogenic alluvial sediments in North Carolina Piedmont gullies indicate swift geomorphic response to 18th century land-use practices

ABSTRACT

Gullies are common erosional features in the Piedmont of North Carolina that have often been studied as indicators of poor land-management practices. However, the timing of gully formation, and thus the specific practices that caused their formation, has been largely overlooked in the literature. Here, we use the timing of gully formation to examine the geomorphic and anthropogenic triggers for erosion in the Piedmont. To do this, we mapped 74 gullies in the landscape and found that most contained alluvium within the gully or in alluvial fans. Soil pits were dug at a subset of the gully sites (16 in alluvium, 1 in colluvium, and 1 upland comparison) and examined for soil development, organic content, and particle size. Seven charcoal fragments were sampled from the soil pits and were radiocarbon dated. Radiocarbon ages cluster in the late 1700s, which suggests that early European settlers had an immediate impact on the landscape through deforestation and agriculture. The swift response of the landscape to deforestation and agriculture indicates that the argillic Piedmont soils are pre-disposed to erosion. Our results highlight the importance of erosion prevention as reforested farmland is cleared during urban expansion.     

Stream-terrace genesis: implications for soil development

Genesis of three distinct types of stream terraces can be understood through application of the concepts of tectonically induced downcutting, base level of erosion, complex response, threshold of critical power, diachronous and synchronous response times, and static and dynamic equilibrium. Climatic and tectonic stream terraces are major terraces below which flights of minor complex-response degradation terraces can form.These three types of terraces can be summarized by describing a downcutting-aggradation-renewed downcutting sequence for streams with gravell bedload. By tectonically induced downcutting, streams degrade to achieve and maintain a dynamic equilibrium longitudinal profile at the base level of erosion. Lateral erosion bevels bedrock beneath active channels to create major straths that are the fundamental tectonic stream-terrace landform. Aggradation events record brief reversals of long-term tectonically induced downcutting because they raise active channels. They may be considered as major (the result of climatic perturbations) or minor (the result of complex-response model types of perturbations). Climatically controlled aggradation followed by degradation leaves an aggradation surface; this type of fill-terrace tread is the fundamental climatic stream-terrace landform. Aggradation surfaces may be buried by subsequent episodes of deposition unless intervening tectonically induced downcutting is sufficient for younger aggradation surfaces to form below older surfaces. Raising of the active channel by either tectonic uplift or by climatically induced aggradation provides the vertical space for degradation terraces to form; first in alluvial fill and then in underlying bedrock along tectonically active streams. These are complex-response terraces because they result from interactions of dependent variables within a given fluvial system. Pauses in degradation to a new base level of erosion, and/or minor episodes of backfilling, lead to formation of complex-response fill-cut and strath, or of fill terraces. Fill-cut terraces are formed in alluvium; they are complex-response terraces because they are higher than the base level of erosion. Good exposures and dating are needed to distinguish static equilibrium complex-response minor strath terraces from dynamic equilibrium tectonic (major) straths. Strath terraces may be regarded as complex-response terraces where degradation rates between times terrace-tread formation exceed the long-term uplift rate for the reach based on ages and positions of tectonic terraces.Late Quaternary global climatic changes control aggradation events and even the times of cutting of major (tectonic) straths, because the base level of erosion can not be attained during times of climatically driven aggradation-degradation events.Most terrace soils form on treads of climatic and complex-response terraces. Aggradation surfaces may provide an ideal flight of terraces on which to study a soils chronosequence. Each aggradation event is recorded by a single relict soil where tectonically induced downcutting is sufficient to provide clear altitudinal separation of the terrace treads. Multiple paleosols are typical of tectonically stable regions where younger aggradation events spread alluvium over treads of older climatic terraces. Pedons on a climatic terrace in a small fluvial system commonly are roughly synchronous - variations of soil properties that can be attributed to temporal differences will be minor compared to altitudinally controlled climatic factors. Climatic terraces of adjacent watersheds also should be roughly synchronous (correlatable) - variations of soil properties that can be attributed to temporal differences will be minor compared to lithologic and climatic factors between different watersheds. Such generalizations may not apply to basins with sufficient relief that geomorphic responses to climatic changes occur at different and overlapping times, and to large rivers whose widely separated reaches are characterized by different response times to climatic perturbations. Soils on climatic terraces of distant watershedswill not be synchronous if their respective aggradation events occur during full-glacial times and interglacial times. Soils on some complex-response terraces may be diachronous within a given fluvial system, and typically are diachronous between watersheds.