Tectonic uplift,sea level changes and Plio‐Pleistocene evolution of a coastal karst system: the Mount Saint Paul (Palawan,Philippines)

The St. Paul karst (Palawan, Philippines) is a tropical coastal karst, consisting of towers, cones, huge depressions and large caves. This area hosts the Puerto Princesa Subterranean River (PPSR, 24 km long), whose main entrance is a large spring along the coast and which is one of the largest cave complexes in eastern Asia. A geomorphological study performed by several field surveys and a morphometric analysis of the digital terrain model (DTM) and 3D cave models, allowed formulation of a first evolutionary framework of the karst system. The DTM was extracted from maps and aerial photographs in order to find different generations of ‘relict’ landforms, through the morphometric analysis of topographic surface and karst landforms. Several features suggest a long and multi‐stage evolution of the karst, whose age ranges from Pliocene to present. The southern and northern sectors of the area differ in their altimetric distribution of caves. In the southern sector, some large caves lie between 300 and 400 m asl and were part of an ancient system that developed at the base level of a past river network. In the northern sector, some mainly vadose caves occur, with a phreatic level at 120–130 m asl. An important phase of base‐level cave development is well documented in the inactive passages of PPSR at 50–80 m asl. Morphological features, such as horizontal solution passages and terraced deposits, suggest a phase of stillstand of the base level, which is recorded in the topography as low‐relief surfaces at 40–50 m asl. The age of this phase is probably Early Pleistocene, on the basis of assumed uplift rates. The more recent caves are still active, being located at the current sea level, but they show more than one cycle of flooding and dewatering (with calcite deposition). In the PPSR, several morphologic features, such as two main water level notches at +12·4 and +7·7 m asl and terraced alluvial deposits, suggest that the lower and active level passed through more than two high‐stands of sea level and so it could have formed throughout most of the Middle‐Late Pleistocene. Copyright © 2010 John Wiley & Sons, Ltd.     

Stock Structure Analysis of the Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier, 1832) Along the China Coast Based on Truss Network

The Japanese Spanish mackerel Scomberomorus niphonius(Cuvier,1832)is widely distributed in the subtropical and temperate waters of the northwestern Pacific Ocean,supporting one of the most important commercial fisheries in China.However,ignoring the potential population structure changes induced by fishing pressure and climate change may undermine the population stability under the current management strategy.In this study,the population structure of the Japanese Spanish mackerel was investigated based on a morphometric truss network system.A total of 534 individuals were randomly collected from commercial gill nets spanning eight major spawning grounds in the Bohai,Yellow,and East China Seas during the peak spawning seasons respectively.A total of 17 measurements(including eye diameter)were conducted in each specimen and subjected to principal component analysis(PCA)and discriminant function analysis(DFA).The results of PCA indicated that the first two factors cumulatively caused 78.38%of the total morphometric variation and observable differences,primarily fin the caudal and trunk areas.The results of DFA revealed that the eight spawning groups can be divided into three stocks,i.e.,southern,middle,and northern stocks,with 68.7%of total accuracy.In contrast to previous studies,the spawning groups of the Japanese Spanish mackerel demonstrated a tendency to disperse to northern regions.In conclusion,this study found that to maintain the stability of the population structure and the total production of Japanese Spanish mackerel S.niphonius(Cuvier,1832),a newly revised management method should be developed and implemented.     

Morphometric aspects of a small tropical mountain river system,the southern Western Ghats,India

Abstract

The Muthirapuzha watershed (MW) is one among the major tributaries of Periyar – the longest west flowing river in Kerala, India. A morphometric analysis was carried out to determine the spatial variations in the drainage characteristics of MW and its 14 fourth order sub-watersheds (SW1–SW14) using Survey of India topographic maps and Landsat ETM⁺ imagery. The study revealed that the watershed includes a sixth order stream and lower order streams dominate the basin. Results did indicate that rainfall has a significant role in the drainage development whereas structure and relief of rocks dictate the drainage pattern. The asymmetry in the drainage distribution is correlated with the tectonic history of the Munnar plateau in the late Paleocene age. The watershed is moderate to well-drained and exhibited a geomorphic maturity in its physiographic development. The shape parameters revealed the elongated nature of MW and drainage network development in the watershed. Further, the analysis provided significant insight into the terrain characteristics. This study strongly brings to light, (a) the tendency of the watershed to soil loss and (b) the hydrological makeup of the sub-watersheds, which combined helped to formulate a comprehensive watershed management plan.     

Digital Terrain Modeling and Industrial Surface Metrology: Converging Realms

Digital terrain modeling has a micro- and nanoscale counterpart in surface metrology, the numerical characterization of industrial surfaces. Instrumentation in semiconductor manufacturing and other high-technology fields can now contour surface irregularities down to the atomic scale. Surface metrology has been revolutionized by its ability to manipulate square-grid height matrices that are analogous to the digital elevation models (DEMs) used in physical geography. Because the shaping of industrial surfaces is a spatial process, the same concepts of analytical cartography that represent ground-surface form in geography evolved independently in metrology. The surface topography of manufactured components, exemplified here by automobile-engine cylinders, is routinely modeled by variogram analysis, relief shading, and most other techniques of parameterization and visualization familiar to geography. This article introduces industrial surface-metrology, examines the field in the context of terrain modeling and geomorphology and notes their similarities and differences, and raises theoretical issues to be addressed in progressing toward a unified practice of surface morphometry.     

Habitat use of inter‐tidal chitons – role of colour polymorphism

This study presents a new approach to examining European chiton habitat use according to morphological characteristics. Time‐search transects were conducted on four Portuguese rocky shores at two shore levels. The chiton species, abundance and individual morphometric features were recorded and related to the substratum dominant epiphytes and surface roughness. The chiton Lepidochitona cinerea (Linnaeus 1767) was the dominant species (77%), followed by Leptochiton algesirensis (Capellini 1859) (15%) and Acanthochitona crinita (Pennant 1777) (8%). Species abundance did not vary significantly with shore level or amongst shores. Six colour morphs were considered for Lepidochitona cinerea, four for A. crinita and one for Lepidochiton algesirensis. Substratum characteristics significantly explained the variation in species and colour morph distribution. There was a high correlation between the presence/absence and type of epiphytic algae and the substratum surface roughness level. We hypothesize that three mechanisms operating either independently or in interaction may explain the non‐random distribution of colour polymorphisms according to their habitat characteristics: (i) presence of algae that are part of their diet; (ii) use of rock as shelter – for instance, crevices and cover resulting from algae fronds and; (iii) morph–rock colour matching as a camouflage mechanism to reduce predation pressure.     

New methodologies for investigating rillenkarren cross-sections: a case study at Lluc,Mallorca

Precise data on the detailed form of 108 rillenkarren (flute) cross-sections at Lluc have been obtained by digitizing photographic enlargements of profile gauge traces taken in the field. Such data enable morphometric analysis to be undertaken more rigorously and on a wider range of characteristics (e.g. flute and cusp asymmetry, surface roughness and the properties of vertical sections) than in previous studies. Methods for quantifying and investigating these characteristics are presented. Since many of the flutes were found to be asymmetrical, the two ‘sides’ of each flute have been analysed separately. Although most of the sides have characteristic parabolic profiles, about one-fifth are rectilinear in form. The parabolic sides are relatively smooth, and this is thought to be attributable to dissolution within the thin film of water present on the surface during rainfall and/or to the detachment of small protruding fragments of limestone (weathered loose by biological agencies) by raindrop impact. The rectilinear sides have distinctly rougher surfaces and are thought to be truncated or immature forms. Sets of rillenkarren on rock outcrops appear to be in dynamic equilibrium, maintaining their overall form over time, but changing in detail as cusp lines shift, existing flutes are captured and new ones are initiated. © 1998 John Wiley & Sons, Ltd.     

The morphological development of alpine valley heads in the Antarctic Peninsula

Glaciation has continued in Antarctica for longer than anywhere else on Earth, so the long-term development of glaciated landforms can be investigated. Complex alpine valley heads up to 36 km wide are found in the Antarctic Peninsula. The largest of these may represent an advanced stage of alpine glaciation, having evolved from the earliest corries which could have developed around the early Oligocene. This study is based on a morphometric analysis of the plan form of 1680 alpine valley heads. This is a much larger sample than used by any previous study. Skewed distributions of dimensional properties (width, length and area) suggest that small corries are continually being added to the population, as older ones are enlarged and some eliminated by coalescence and ice sheet erosion. Very large features are found only in parts of Graham Land and Alexander Island, where lack of high-level ice sheet erosion has allowed the forms of mountain glaciation to dominate the landscape. The attainment of an equilibrium planform shape is suggested by the persistence of an equidimensional form, the development of characteristic or limiting values of other morphometric properties, e.g. planform closure and basin order, and by the intercorrelation of morphometric properties. A combination of branching and coalescence is fundamental in the development of corries. The latter results both in widening, which counteracts the tendency towards lengthening observed by other workers, and also in a limit to basin complexity. © 1998 John Wiley & Sons, Ltd.     

Digital Terrain Modeling and Industrial Surface Metrology: Converging Realms

Digital terrain modeling has a micro‐ and nanoscale counterpart in surface metrology, the numerical characterization of industrial surfaces. Instrumentation in semiconductor manufacturing and other high‐technology fields can now contour surface irregularities down to the atomic scale. Surface metrology has been revolutionized by its ability to manipulate square‐grid height matrices that are analogous to the digital elevation models (DEMs) used in physical geography. Because the shaping of industrial surfaces is a spatial process, the same concepts of analytical cartography that represent ground‐surface form in geography evolved independently in metrology. The surface topography of manufactured components, exemplified here by automobile‐engine cylinders, is routinely modeled by variogram analysis, relief shading, and most other techniques of parameterization and visualization familiar to geography. This article introduces industrial surface‐metrology, examines the field in the context of terrain modeling and geomorphology and notes their similarities and differences, and raises theoretical issues to be addressed in progressing toward a unified practice of surface morphometry.