Ancient Erosion Research Articles

SEAFLOOR MORPHOLOGY OF THE OB RIVER GULF, KARA SEA

The article presents the results of an extensive study of the bottom topography of the Ob River Gulf in the Kara Sea, which is a follow-up to the long-term studies of the authors. It refines the existing ideas and aims at solving a fundamental problem of reconstructing the conditions for the formation of bottom topography in the shallow bays of the Kara Sea in the Late Pleistocene and Holocene. The work aims to create a regional characteristic of the geomorphologic structure of the Ob River Gulf bottom. The initial data on the bottom topography were taken from marine navigational maps and sounding boards at a scale of 1:50 000 - 1:100 000. We processed and interpreted the collected cartographic material to create a detailed DEM of the bottom and a bathymetric map at a scale of 1:200 000 with an isobaths interval of 1 m. In addition to bathymetric data, the compilation of a geomorphologic map engaged a large amount of literature and stock materials on geomorphology, geology, and geocryology of the region. The original morphogenetic legend was elaborated with due account of current ideas regarding the conditions for the formation of periglacial plains relief at the regressive stage of the Kara Sea shelf evolution. It was found that the relict fluvial relief prevails within the gulf and was partly modified by subaqueous processes during post-LGM transgression and the current epoch. We have indicated the most critical features of the structure and pattern of the flooded pravalley of the Ob River, as well as the total ancient erosion network. The selected individual forms and relief elements take into account the scale of objects and the degree of their generalization on the map and give an idea of the development of relief-forming processes both at the subaerial stage and under subaqueous conditions, including specific features of modern dynamics of the coastal and bottom relief.

Method for Revealing Placer Gold Source

Material characteristics of placer gold and geological and geomorphological features of placercontaining watercourses allow revealing the type of source that formed the placer. The studied area (the middle reach of theAdychaRiver, Verkhoyansk District, Yakutia) is characterized by highly developed placer gold mineralization both in ancient terrace sediments and high-order watercourses. The significant placer gold mineralization in the high-order watercourses, at very limited number of known bedrock gold deposits suggests the presence of not yet discovered bedrock gold mineralization. Revealing the type of sources of placer gold in young high-order watercourses allows to create prognostic and prospecting models for both potential placer and primary (vein) ore occurrences. The purpose of the study is to compile a logical-information algorithm, which, based on the most significant material and geological-geomorphological factors, will enable revealing the type of placer gold source and the possibility of its location discovery and probability of gold transportation continuation from the source. The study result is presented by a program (the Python programming language) that characterizes the type of placer gold source based on gold grain rounding degree, the presence of gold intergrowths with other minerals and the presence of heavy fraction. Assessment of the possibility of placer gold source location determination is based on geological and geomorphological factors: watercourse order, the type of placer, and spatial association with terraces of ancient erosion levels. The study of well-known gold placers using the created program allowed revealing gold placers with supposedly primary gold source and other ones with the source in the form of a natural intermediate gold concentrator. A map of exogenous gold mineralization with forecast elements was also created, presenting areas promising for revealing primary gold mineralization (areas of presence of high-order watercourses with gold mineralization source) and areas of high-order watercourses promising for discovering gold placers (identified by analogy (in geological and geomorphological position) with watercourses with the known source in the form of natural intermediate gold concentrator.

Namtso Ancient Lagoon and Ancient Sea Erosion Landform

During a certain geological period, the sea surface is at the current elevation of about 4746-4755 meters. When the sea surface is about 4746-4755 meters above sea level, the Namtso region of Tibet is a lagoon in the sea. The sea surface was kept stable at the above location for a long time, and a lot of sea erosion landforms were generated on the coast. The ancient sea erosion caves, sea erosion pillars, sea erosion arch bridges, sea erosion headlands, sea erosion headlands, sea erosion cliffs, sea erosion platforms and other various ancient sea erosion micro-landforms are well preserved on the banks of Namtso Lake. It is a unique and natural ancient coastal landscape park in the world

Enrichment laws and scale effective development of shale gas in the southern Sichuan Basin

Based on the newest understandings of geological assessment and new progresses in engineering technologies in the development of shale gas rich in the southern Sichuan Basin, this paper analyzed the shale gas enrichment laws and the key factors of its commercial production, discussed the scale and efficient development modes, and clarified the further developing orientation. The following findings were concluded. (1) The Lower Silurian Longmaxi shale is the sweetest spot in this study area with a low density and a high uranium/thorium (U/Th) ratio, TOC content, quartz content, and free gas content. Besides, its distribution laws are mainly controlled by the sedimentary facies of deep water shelf. (2) The overpressured zones away from the ancient (present) erosion zones and large faults, mainly controlled by multi-stage tectonic evolution, belong to the most favorable sweet spots not only because there are well-developed organic matters and pores but the produced gas there is mainly of secondary cracking retention oil. (3) Layout, drilling, completion (fracturing) and management of wells will be essential to achieve high productions in the shale gas production. (4) The existing main technologies have helped achieve efficient development of quality shale gas resources underground less than 3500 m in such national shale gas demonstration zones as Changning–Weiyuan, Zhaotong, etc. Also, there shows a good potential of shale gas resources in those shallower strata and the strata with the burial depth of 3500–4000 m. In conclusion, with the help of continuous progress in technologies, an annual shale gas production rate of 40 billion cubic meters will be possibly achieved in this study area.

Gas accumulation conditions and key technologies for exploration & development of Sinian and Cambrian gas reservoirs in Anyue gasfield

Exploration of the Sinian-Lower Paleozoic formations in the Sichuan Basin starts from the 1950s, and is tortuous and complex. To summarize the exploration experiences is of great significance of reference for exploration of oil and gas in deep carbonate rocks of the Sichuan Basin. Gas accumulation in the Anyue oversize gasfield is chiefly controlled by the Deyang-Anyue intra-platform rift and central Sichuan paleouplift. The intra-platform rift controls the scale hydrocarbon generation center and effective hydrocarbon plays. The Anyue gasfield is characterized by near-source hydrocarbon accumulation. The marginal zone of intra-platform rift and high part of the paleouplift control the scale distribution of favorable facies belts of reservoir development, and overlapped by paleokarstic reformation, the reservoirs are widely distributed. The intra-platform rift and paleouplift jointly control formation of the scale traps and hydrocarbon enrichment. Gas reservoir features and major controlling factors for hydrocarbon accumulation have some differences in the main play strata, such as Longwangmiao Formation, and Member 4 and Member 2 of Dengying Formation. The gas reservoir in the Longwangmiao Formation is a lithologic gas reservoir under the tectonic setting, and the inherited paleouplift is a key for reservoir formation and hydrocarbon accumulation. The gas reservoir in the Member 4 of Dengying Formation is mainly controlled by large structural-stratigraphic composite traps, and the gas reservoir in the Member 2 of Dengying Formation is the structural trap. Distribution of the large gasfields in the Dengying Formation is controlled by the intra-platform rift, near-source hydrocarbon-reservoir configuration controlled by the ancient erosion plane and stratigraphic sealing in the updip direction. For exploration and development of the Anyue gasfield, four series of technologies are developed, namely, reservoir seismic fine description technology, well logging fine evaluation technology of gas layers, fast drilling technology of complex strata, and stimulation technology for high temperature and high pressure gas layers. Technical progresses provide powerful guarantee for efficient exploration and development of the oversize gasfields.

Landscape evolution in Africa during the Cenozoic and Quaternary—the legacy and limitations of Lester C. King

African landscape evolution since 66 Ma reflects interactions among parts of the Earth system from the Core to the Biosphere. We stress changes in those interactions in three events that have dominated landscape development: (i) a climatic revolution when the circumpolar current and the East Antarctic ice sheet first formed ∼37 Ma; (ii) a tectonic revolution at ∼32 Ma dominated by elevation of ∼30 topographic structural swells continent-wide; and (iii) a second climatic revolution in a Northern Hemisphere cooling event (at ∼2.7 Ma) that triggered Sahara desert initiation and the beginning of glacial cycles in the Northern Hemisphere (∼2.15 Ma). We recognize the following distinct features of the great Afro-Arabian continent (∼40 M km2) that show its relationship to Earth structure and processes: deep mantle structure and dynamics, plate motion with respect to that structure, especially plate-arrest (∼32 Ma). The topographic, erosional, geomorphic, and depositional modifications following that tectonic event were strongly influenced by changes around the continent in oceanic and atmospheric circulation that affected the entire continent. Atmospheric circulation changes since ∼34 Ma have involved zonal winds, the ITCZ, desert formation and destruction, the evolution of the persistent (since ∼35 Ma) Antarctic ice sheet, and since ∼2 Ma of the rapidly cycling Eurasian ice sheets. We explain that a widely supported idea that ancient erosion surfaces have survived at high elevations in Africa is the result of a failure to recognize that the present elevations of the continent’s swells are dynamically maintained, but do not display a thermochronological signature because they are young (less than ∼32 My), so that conduction of heat from shallow convection cells has not yet reached the Earth’s surface.

Radiocarbon anomalies suggest late onset of agricultural intensification in the catchment of the southern part of the Yangtze Delta, China

Previously underused information from radiocarbon dates in well-characterised sedimentary sequences in the southern Yangtze Delta, China, is here utilised in reconstruction of patterns of ancient erosion. The southern Yangtze Delta was an important focus of food production in the early Neolithic. Anomalous radiocarbon dates in Holocene sediments from the southern part of the delta are unevenly distributed through time. Two clusters of dates – in sediments ca. 9000–7000cal. BP and ca. 3000–1000cal. BP – most likely indicate two periods of intensive erosion and redeposition of organic materials. The older of the two clusters may have been associated with a marked episode of marine transgression, whereas the younger cluster could reflect increasing levels of human disruption of soils and sediments in the catchment. A relatively late increase in anthropogenic soil erosion supports recent archaeological evidence that, following its early Neolithic origins, agricultural expansion and intensification occurred later on the southern Yangtze Delta than previously thought.

火星衝突クレーターの特異なエジェクタ地形と劣化過程

Mars has fascinated us in terms of discovering vital activities and examining planetary surface evolutions. Recent explorations detected subsurface ice and methane, which reveal the importance of investigating ancient environments and their evolution. Impact craters and their ejecta morphologies are natural probes for obtaining knowledge on ancient surface and subsurface environments, because detailed morphologies of impact craters and their ejecta are sensitive to impact conditions and degradation processes. Martian enigmatic ejecta morphologies and their currently-proposed origins are summarized, and some degradation processes effective on Martian craters are introduced. Ejecta of Martian impact craters are different from those of lunar or Mercurian impact craters. They possess clear distal ridges and cliffs, and are diverted by preexisting obstacles, while edges of lunar or Mercurian ejecta are ambiguous. Their unique morphologies suggest that the ejecta are emplaced by radial ground-hugging flows generated at the time of the impact. Processes and agents of the fluidization draw attention, because the atmosphere and/or subsurface volatiles are suggested for its formation. Degradation processes on Mars vary, and include superimposed impacts, viscous relaxation, mass movements, lava infilling, fluvial incision, gully formation, lacustrine erosion and deposition, ice-related processes, and airfall deposition. Due to high ancient erosion rates, degraded crater morphologies also provide useful information on the ancient environment.

Enhanced erosion rates on Mars during Amazonian glaciation

Observations of Mars from the surface and from orbit suggest that erosion rates over the last ∼3Gyr (the Amazonian) have been as slow as 10−5m/Myr and have been dominated by aeolian processes, while ancient (Noachian) erosion rates may have been orders of magnitude higher due to impact bombardment and fluvial activity. Amazonian-aged glacial deposits are widespread on Mars, but rates of erosion responsible for contributing debris to these remnant glacial deposits have not been constrained. Here, we calculate erosion rates during Amazonian glaciations using a catalog of mid-latitude glacial landforms coupled with observational and theoretical constraints on the duration of glaciation. These calculations suggest that erosion rates for scarps that contributed debris to glacial landforms are 4–7 orders of magnitude higher than average Amazonian rates in non-glaciated, low-slope regions. These erosion rates are similar to terrestrial cold-based glacier erosion and entrainment rates, consistent with cold-based glacier modification of parts of Mars.

LATE PLEISTOCENE CYCLE OF EROSION DISSECTION AND INFILLING OF THE DRAINAGE NETWORK IN THE NORTH-EASTERN STAVROPOL'E (PAPER 2. RECENT BALKAS. HISTORY OF THE DRAINAGE NETWORK)

In the northeastern Stavropol Highland erosion network depth and density were much higher at the Middle/Late Pleistocene (MP/LP) boundary than at present. During the Valdai (Vistulian) cold epoch of the LP, erosion network was filled with slope and alluvial deposits. Probable incision in the Late Glacial interrupted the infilling tendency, but the erosion network rejuvenation had much smaller scales compared to the preceding erosion dissection. Therefore, the upper reaches of the erosion network at the MP/LP boundary were almost buried and transformed into hollow systems by the beginning of the Holocene, while in lower reaches thick LP deposits make wide valley bottoms. In the Holocene, sedimentation processes proceeded both in hollows and in small valleys, but their rates decreased considerably. Land cultivation started in the region in the middle XIXth century. During the last 150 years, sedimentation in valley and hollow bottoms continued to prevail over erosion. This shows that artificial lowering of landscape sustainability by land cultivation has not led to incision along the modern and ancient erosion network. The probable explanation is that modern climate is not so favorable for erosion as it was at the MP/ LP boundary and in the Late Glacial.

LATE PLEISTOCENE CYCLE OF EROSION DISSECTION AND INFILLINOF THE DRAINAGE NETWORK ON THE NORTH-EASTERN STAVROPOL'E (PAPER I. THE NETWORK OF HOLLOWS)

Systems of hollows were detected on satellite images in the north-eastern Stavropol Upland. Their density is several times greater than that of the recent erosion network. Spatial pattern of the systems evidence their fl uvial origin. A case study of one of the hollows in the Aigurka River catchment included fi eld investigation of its morphology and geological composition and laboratory study of the hollow sedimentary infi ll. We have concluded that the hollow systems represent upper reaches of an ancient erosion network, which were fi lled with deluvial and solifl uction deposits during the Valdai (Vistulian) cold epoch in the Late Pleistocene.

Ancient pre-glacial erosion surfaces preserved beneath the West Antarctic Ice Sheet

Abstract. We present ice-penetrating radar evidence for ancient (pre-glacial) and extensive erosion surfaces preserved beneath the upstream Institute and Möller ice streams, West Antarctica. Radar data reveal a smooth, laterally continuous, gently sloping topographic block, comprising two surfaces separated by a distinct break in slope. The erosion surfaces are preserved in this location due to the collective action of the Pirrit and Martin–Nash hills on ice sheet flow, resulting in a region of slow flowing, cold-based ice downstream of these major topographic barriers. Our analysis reveals that smooth, flat subglacial topography does not always correspond to regions of either present or former fast ice flow, as has previously been assumed. We discuss the potential origins of the erosion surfaces. Erosion rates across the surfaces are currently low, precluding formation via present-day glacial erosion. We suggest that fluvial or marine processes are most likely to have resulted in the formation of these surfaces, but we acknowledge that distinguishing between these processes with certainty requires further data.

Basal roughness of the Institute and Möller Ice Streams, West Antarctica: Process determination and landscape interpretation

We present a detailed analysis of bed roughness beneath Institute and Möller Ice Streams, west Antarctica, using radio-echo sounding data (RES) acquired in the austral summer of 2010/11. We assess roughness using a two-parameter approach and also assess the directionality of roughness relative to present-day ice flow. Our work highlights the wealth of additional information that resides in analyses of bed roughness. Employing these multiple approaches we show that spatially variable roughness patterns are partly a consequence of the ability of flowing ice not only to smooth the bed but also to redistribute and remove sediments, and to do this along-flow. Accordingly, we identify some fast-flow tributaries underlain by topography that has been streamlined and other tributaries that are underlain by sediments. We also identify locations that are currently protected from erosion, but where more ancient erosion may once have occurred. We conclude that detailed roughness analysis is a useful tool for landscape interpretation; and we suggest that the roughness of an ice-sheet's bed should be viewed not only as the consequence of ancient marine sedimentation, but also as a product of more contemporary erosion and redistribution of sediments, as well as bedrock-smoothing that is ongoing because of continuing dynamic activity. In this way, basal roughness has the potential to evolve continually with ice sheet form and flow, and should not be viewed simply as a snapshot of either present-day or palaeo-basal conditions.

Geomorphologic context and proposed chronostratigraphic position of Lower Palaeolithic artefacts from the Op de Schans pit near Kesselt (Belgium) to the west of Maastricht

AbstractIn July 2007 an important archaeological find was made in the Op de Schans loess pit near Kesselt (Belgian Limburg) immediately to the west of the Dutch city of Maastricht. During an archaeological rescue dig, three Lower Palaeolithic artefacts were recovered from the infill of an ancient erosion gully: a bifacial side-scraper, an atypical biface and a cortical flake. Typologically, the artefacts can be classified as Acheulean. In this region, harbouring several such brickyard pits, these are the oldest artefacts yet found, prompting further investigations into the stratigraphic position of the archaeological layer. The Op de Schans pit, which has yielded several Middle Palaeolithic occupation horizons, is located in the middle of an ancient sediment trap. Because of this exceptional geomorphologic situation, multiple ancient sediments have been preserved which elsewhere were entirely removed during subsequent erosion phases. Here five separate loess beds with intercalated interglacial palaeosols are present, overlying the deposits of the River Maas (Meuse). This sequence has been used as a hypothetical framework for elaborating a chronostratigraphic model. The archaeological level in question, discovered at the base of a subsequently infilled erosion gully, can most likely be chronostratigraphically dated to around the start of Marine Isotope Stage 10 (MIS 10), in the era of the Pottenberg discordance (approx. 390 ka). However, the possibility cannot be excluded that the gully in which the artefacts were found dates from an early phase of MIS 12 (approx. 480 ka). The age may in fact be greater still, as the artefacts have been eroded out of their original, primary context and subsequently deposited in the gully. Hypothetically, they may even have been taken up from the Maas loam of the Kesselt Maas terrace (MIS 13) that here is situated directly below the archaeological horizon. This would make the maximum age of the artefacts recovered from the gully around 500 ka.

Overview of a Special Issue on “Geotectonic Evolution of the Japanese Islands under New Paradigms of the Next Generation (Part I-III)”

This article provides an overview of papers collected in the special issue titled “Geotectonic Evolution of the Japanese Islands under New Paradigms of the Next Generation (Part I-III)” for international readers. Research on the geologic evolution of the Japanese Islands started from the geotectonic subdivision with definitions of elements and boundaries in the late 19th century. Traditionally, some remarkable faults, such as Median Tectonic Line (MTL), Fossa magna, and Tanakura Tectonic Line (TTL), were regarded as the most important; however, these apparent features were in fact formed during the Miocene opening of the Japan Sea, whereas the major structures of Japan were made by the Pacific-type orogenies throughout the Phanerozoic after the initiation of subduction at 520 Ma (the Cambrian). Marine geophysicists have realized that the formation of accretionary complex (AC) along modern active subduction zones is rather exceptional; instead, tectonic erosion takes place dominantly. The estimated addition rate of juvenile arc crust (composed of tonalite–tronjemite–granodiorite suite; TTG) is negative at present for the entire globe, i.e., the total volume of the continental crust is currently decreasing. This indicates that tectonic erosion must also have occurred effectively in the past, and that its geological remnants need to be investigated carefully. A possible proxy geologic body for ancient tectonic erosion is a serpentinite melange, which often includes calc-alkaline volcanics and coeval high-P/T blueschists within serpentinite matrices as shown in the geology of Japan. The large-scale shortening of a fore-arc crust can occur solely due to tectonic erosion, which may involve more than 150 km-wide areas of missing rocks between volcanic arc and trench. The sporadic occurrence of tectonic blocks of older (520-150 Ma)TTG rocks in serpentinite melange indicates that four arc crusts, out of the five made by Pacific-type orogeny in Japan during the past 500 million years, have already been consumed. The Pacific-type orogeny was revisited after recent critical discoveries of; (1) orogenic core of high-P/T regional metamorphic belt as a thin (< 2 km) solid high-T intrusion, bounded on the top and bottom by a paired fault; (2) rapid increase of 200-300 km-wide TTG belt formed by slab-melting; (3) these culminated with an approaching mid-oceanic ridge, associated with large-scale tectonic erosion; and (4) formation of an AC after ridge subduction and doming up of a sandwiched set of high-P belt and accretionary belt below and above. The Pacific-type orogeny has been ignored since the “terrane plague”; however, Pacific-type orogeny dominated to increase the TTG crust leading to the births of continents and supercontinent by 1.8 Ga. The extensive tectonic erosion and arc subduction through time, suggesting 10 times more TTG materials, enriched with radiogenic elements, floated at the bottom of the mantle transition zone, which generated heat to warm up the mantle up to 200 K within 100 million years in the Archean, and to 100 K in the Phanerozoic. Subducted TTG and presence of second continents in the mid-mantle may explain more general aspects of mantle dynamics, and the concept may become a frontier of solid Earth science in the 21st century. From the viewpoint of the history of science, the previous geological studies in Japan since the Meiji Era are also summarized briefly, with special reference to the orogeny, tectonics, and geotectonic subdivision of the Japanese Islands.

The Guayana Highlands: A Promised (but Threatened) Land for Ecological and Evolutionary Science1

THIS COMMENTARY STRESSES THE POTENTIAL SIGNIFICANCE OF THE GUAYANA HIGHLANDS, in northern South America, to provide evidence for relevant biogeographical and evolutionary theories that are being intensively discussed. Some regions of the world seem to be especially well suited for this purpose, as is for example the case of the Galapagos Islands, the Panama Isthmus, Beringia, or the Amazon basin. Singular features of these areas include a key emplacement with respect to Earth’s biogeographical regions, unique and specialized life forms, amazing biodiversity and endemism levels, or highly pristine ecosystems, among others. The remote and mysterious Guayana Highlands—the A. C. Doyle’s (1912) “Lost World,” at the top of characteristic sandstone table mountains (tepuis) of the Neotropical Guayana region, could have a place among these privileged areas (Fig. 1). The Guayana Highlands (GH), also known as Pantepui, constitute a singular biogeographical province of about 5000 km2, split into numerous topographical islands between about 1500 and 3000 m altitude (Huber 1994). Pantepui lies on the Precambrian Guayana Shield, which had been separated from the African Shield by continental drift, leading to the formation of the Atlantic Ocean, around 80–100 million years ago (Edmond et al. 1995). The tepuis are remnants of ancient erosion surfaces that have been isolated by denudation due to the Gondwana breakup and the formation of the extensive Orinoco and Amazon river basins (Briceno & Schubert 1990). The uniqueness of the GH biota, as well as its striking degree of biodiversity and endemism, are well known and have been recognized for long time (Huber 2005). This is especially manifest in vascular plants, the better known organisms of the region (Berry et al. 1995), with ca 630 genera and 2500 species, of which 42 percent are endemic to the GH and 25 percent are endemic to a single tepui (Berry & Riina 2005). As a consequence, the GH have been traditionally considered an important speciation center of the Neotropics (e.g., Funk & Brooks 1990). Furthermore, the GH lie in a strategic geographical location, among key Neotropical areas such as the Amazon basin, the Caribbean region, and the Atlantic domain (Huber 1995). In addition, the almost pristine nature of the tepui summits make them unique environments to record natural environmental variability, and hence to test hypotheses about climatic or nonclimatic forcing, and the corresponding ecosystem responses. Here, the main biogeo-

Record of emergent continental crust ∼3.5 billion years ago in the Pilbara craton of Australia

ISOTOPIC data for the Earth's oldest rocks1–7 imply that a considerable volume of continental crust existed during the early Archaean aeon (>3.0 Gyr ago), but it is not known when this crust first began to form emergent landmasses. Sedimentary geochemistry suggests8,9that the area of exposed continent was negligible until late in the Archaean10, a contention supported by the fact that, until now, all greenstone supracrustal volcanic and sedimentary successions shown to have been deposited on eroded continental basement have yielded ages of ≲3.0 Gyr. Here we report the discovery of an angular unconformity (an ancient erosion surface) beneath rocks of the 3.46-Gyr Warrawoona Group in the Pilbara craton of Australia, currently the oldest known well-preserved greenstone succession. Below the unconformity, low-grade greenstones older than 3.5 Gyr were intruded by voluminous granitoids before erosion. As the overlying Warrawoona rocks are only mildly metamorphosed, slightly deformed and were deposited near sea level, we infer that they accumulated on crust that was already rigid, cool and buoyant. Thus, by 3.46 Gyr ago, the sub-Warrawoona rocks formed an emergent block of continental crust, the most ancient known.

The quintessential systematist: Henri Baulig

The French geomorphologist Henry Baulig (1877–1962) studied with W.M. Davis between 1905 and 1911. Following this master, he espoused the theory of the geomorphic cycle but also gave an eminent role to eustatism — both Quaternary glacio-eustatism and Pliocene diastrophic eustatism (i.e., the rise or fall of sea level caused by submarine tectonism). He believed that large parts of continents had remained stable since the start of the Pliocene, and that they retain undeformed remnants of ancient erosion levels. He opposed Walther Penck's Piedmonttreppen theory. He also attempted to reconstruct the polycyclic profiles of rivers and peneplain surfaces, but his method of identifying ancient flattened surfaces by statistical and graphical means never gained wide acceptance. Among Baulig's regional works, a morphological study of the Massif Cenral and a two volume, much appreciated, geography of North America are noteworthy. He has also left us the French-English-German Vocabulary of Geomorphology, which is an extraordinary work of scholarship. Baulig was sceptical of quantification and process studies, preferring to rely on perceived morphology. Specific relief forms such as sugar-loaf shaped rocky domes and inselbergs did not much interest him, but he was aware, better than sometimes stated, of climatic geomorphology. Although his rigorous, analytical, and somewhat theoretical way of arguing isolated him from some geographers who were keen on new, adventurous ideas, his work remains an outstanding model.

Formation Process and Amelioration of the Loess Plateau in China

Abstract Based on the formation process of the Loess Plateau, the characteristics comparison between loess and ancient soil and the located materials of spore- pollen, ancient stone artifact, history, geography and soil erosion, the analysis reveals that the present state serious soil erosion in Loess Plateau, instead of being a natural geologic course, is a consequence of destruction of vegetation, irrational land utilization and the direct destruction of soil permeability and anti-erosion ability, esp. anti-scourability. The water and soil conservation measures, with the twenty-eight-word amelioration principle as the core, are the basis for exploiting and improving water and soil resources of the Loess Plateau so as to harness the Huanghe (the Yellow River).

The Nature of Mountain Geomorphology

A century of study suggests many common characteristics in the geomorphic nature of high mountain areas. These include important structural influences in the landscape, usually on a variety of spatial scales, and contrasting climatic conditions (often confounded with vegetation distributions) which also exhibit a wide spatial variability. Most high mountain terrain also shows evidence of ancient erosion surfaces as well as that of past glacial action and other, less direct, consequences of late-Pleistocene environmental changes. The resulting landscape is one of high relief and highly variable potential energy. This is reflected in a history of recent erosion by large catastrophic events and a high potential for accelerated erosion where mountain terrain is impacted by man's activity. Such common characteristics suggest that mountain geomorphology be considered as a regional component within geomorphology.