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At least 19 records

Geomorphology subprogram: Geomorphological map of Occidental region of Bolivia, utilizing ERTS imagery

The author has identified the following significant results. Due to the receipt of ERTS-1 imagery, Bolivia will have for the first time a geomorphological map at a scale of 1:100,000. Now the researcher and the student will be able to compare the distribution of the existing shapes of the country, which have been modelled by diverse processes, factors, and agents. This geomorphological information will be very useful in its application to mining, especially alluvial beds, engineering work, and other geological studies. This map is divided into ten geomorphological units which coincide with the geostructural units of the western region of the country.

Brockmann, C. E.↗

Geomorphology and Geology of the Southwestern Margaritifer Sinus and Argyre Regions of Mars. Part 1: Geological and Geomorphological Overview

Based upon Viking Orbiter 1 images of the southwestern portion of the Margaritifer Sinus Quadrangle, the northwestern portion of the Argyre Quadrangle, and a small portion of the southeastern Coprates Quadrangle, three major mountainous of plateau units, seven plains units, and six units related to valley forming processes were identified. The photomosaic is oriented such that it provides good areal coverage of the upper Chryse Trough from Argyre Planitia to just above Margaritifer Chaos as well as of plains units on either side of the Trough. The photomosaic was compiled from Viking Orbiter 1 images ranging in resolution from approximately 150 to 300 meters per pixel printed at a scale of about 1:2,000,000. The characteristics of each geomorphic unit are outlined.

Parker, T. J.↗

ERTS: A multispectral image analysis contribution for the geomorphological evaluation of southern Maracaibo Lake Basin

Multispectral analysis of ERTS-A images at scales of 1:1,000,000 and 1:500,000 has been conducted with conventional photointerpretation methods. Specific methods have been developed for the geomorphological analysis of southern Maracaibo Lake Basin which comprises part of the Venezuelan Andean Range, Perija Range, the Tachira gap and the Southern part of the Maracaibo Lake depression. A steplike analysis was conducted to separate macroforms, landscapes and relief units as well as drainage patterns and tectonic features, which permitted the delineation of tectonic provinces, stratigraphic units, geomorphologic units and geomorphologic positions. The geomorphologic synthesis obtained compares favorably with conventional analysis made on this area for accuracy of 1:100,000 scale, and in some features with details obtained through conventional analysis for accuracy of 1:15,000 and field work. Geomorphological units in the mountains were identified according to changes in tone, texture, forms orientation of interfluves and tectonic characteristics which control interfluvial disimetrics.

Salas, F.↗

Foundational Women in Planetary Geomorphology: Some Contributions in Fluvial, Aeolian, and (Cryo)Volcanic Subdisciplines

Despite undeserved challenges to participation in the field of planetary geomorphology, women have made significant contributions in the fluvial, aeolian, and (cryo)volcanic subdisciplines. In this work, some women—in particular, women of color—are highlighted to show a part of these foundational contributions. We focused on women scientists who were working in the latter half of the 20th century, a revolutionary time for terrestrial geomorphology and the inception of the discipline of planetary geomorphology. We also focused on women working in our scientific subdisciplines so that we could provide proper context for their work. These contributions have occurred both as discoveries in terrestrial geomorphology leading to follow-on discoveries in planetary geomorphology and through serving as educators and role models. With women increasingly achieving positions of influence both in the geo- and planetary sciences as in American society, this research allows us to celebrate these contributions of women and particularly women of color while looking forward to a more complete record of their past contributions and greater future achievements.

Devon M Burr↗

Applications of Skylab EREP photographs to mapping landforms and environmental geomorphology in the Great Plains and Midwest

The following evaluations of Skylab photographs were undertaken: (1) the 1290 Skylab S190A and S190B photographs of Illinois, Iowa, Kansas, Missouri, Nebraska, and South Dakota were evaluated in detail in terms of coverage, cloud cover, photographic quality, endlap, detectability of roads and stereorelief, and utility for geomorphologic mapping, and (2) the utility of the Skylab photos were tested for interpretive analytic mapping of geomorphologic features over large areas representative of different parts of this region. Photointerpretative maps of analytic geomorphology were obtained for various test areas representative of the varied landscapes in the region. These maps are useful for regional land-use planning, ground-water exploration, and other environmental geomorphologic-geologic applications. Compared with LANDSAT-1 MSS images, Skylab photos afford almost as extensive overviews of large areas but in considerably greater detail, and for many SL photos, moderate stereorelief. However, repetitive multiseasonal, cloud-free coverage by high-quality photos is very limited and many areas have no coverage at all.

Morrison, R. B.↗

Techniques, problems and uses of mega-geomorphological mapping

A plea for a program of global geomorphological mapping based on remote sensing data is presented. It is argued that the program is a necessary step in bringing together the rapidly evolving concepts of plate tectonics with the science of geomorphology. Geomorphologists are urged to bring temporal scales into their subject and to abandon their recent isolation from tectonics and geological history. It is suggested that a start be made with a new geomorphological map of Europe, utilizing the latest space technology.

Embleton, C.↗

Geomorphology and reflectance patterns of vegetation-covered dunes at the Tsodilo Hills, north-west Botswana

Seasonal reflectance variations in semigrid environments provide a means of assessing vegetation health and density as well as monitoring landform processes. Multitemporal Landsat Thematic Mapper scenes with field measurements are used to map geomorphology and vegetation density in a stabilized dune environment and to measure seasonal reflectance changes for a series of ten geomorphological and vegetation units on the Kalahari-age linear dunes. Units were chosen based on differences in landform and proportion of trees, forbs and bare soil. Reflectance curves and normalized-difference vegetation indices (NDVI) show that dune crests have the strongest seasonal variability in color and brightness. The geomorphological link with reflectance and NDVI values are linked to biomass production and zoning of vegetation with slope, drainage and subtle soil differences.

Jacobberger, P. A.↗

Mapping of land use and geomorphology in the APAPORE project area by LANDSAT satellite data, volume 1

The results of a land use and geomorphological mapping of the so-called Projeto APAPORE area, at Mato Grosso do Sul State are presented. The study was carried out using multispectral scanner (MSS) and return beam vidicon LANDSAT images (channels 5 and 7 for the MSS) at the scale of 1:250,000 from 1980 through visual interpretation. The results indicate that pastureland is the most widespead class and that the agricultural areas re concentrated in the north of the area under study. The area covered with cerradao (arboreous savanna type) has a great areal extention, thus permitting the advance of the agricultural frontier. The geomorphological mapping can be useful to regional planning of future land use within the studied area.

Parada, N. D. J.↗

A New Global Geomorphology?

Geomorphology is entering a new era of discovery and scientific excitement centered on expanding scales of concern in both time and space. The catalysts for this development include technological advances in global remote sensing systems, mathematical modeling, and the dating of geomorphic surfaces and processes. Even more important are new scientific questions centered on comparative planetary geomorphology, the interaction of tectonism with landscapes, the dynamics of late Cenozoic climatic changes, the influence of cataclysmic processes, the recognition of extremely ancient landforms, and the history of the world's hydrologic systems. These questions all involve feedback relationships with allied sciences that have recently yielded profound developments.

Baker, V. R.↗

Geomorphology, tectonics, and exploration

Explorationists interpret satellite images for tectonic features and patterns that may be clues to mineral and energy deposits. The tectonic features of interest range in scale from regional (sedimentary basins, fold belts) to local (faults, fractures) and are generally expressed as geomorphic features in remote sensing images. Explorationists typically employ classic concepts of geomorphology and landform analysis for their interpretations, which leads to the question - Are there new and evolving concepts in geomorphology that may be applicable to tectonic analyses of images?

Sabins, F. F., Jr.↗

Space imagery and some geomorphological problems of the Guiana Shield, South America

Some ongoing involvement in regional geomorphologic research in South America is described. Because of association with LARS at Purdue University, there has been engagement, vicarious or adivsory, in projects which led to LANDSAT 1-2 mapping of the natural resources of Bolivia (1:8,000,000 scale), and preparation of a geographic information system which mapped the general hydrology, geology, soils, and vegetation of Ecuador (1:4,000,000 scale). Currently we are involved more specifically in geological-geomorphological mapping of the Venezuelan portion of the Guiana shield, and because of manuscript limitations only questions pertinent to this region are posed in the ensuing discussion.

Melhorn, W. N.↗

Geomorphology from space: A global overview of regional landforms

This book, Geomorphology from Space: A Global Overview of Regional Landforms, was published by NASA STIF as a successor to the two earlier works on the same subject: Mission to Earth: LANDSAT views the Earth, and ERTS-1: A New Window on Our Planet. The purpose of the book is threefold: first, to serve as a stimulant in rekindling interest in descriptive geomorphology and landforms analysis at the regional scale; second, to introduce the community of geologists, geographers, and others who analyze the Earth's surficial forms to the practical value of space-acquired remotely sensed data in carrying out their research and applications; and third, to foster more scientific collaboration between geomorphologists who are studying the Earth's landforms and astrogeologists who analyze landforms on other planets and moons in the solar system, thereby strengthening the growing field of comparative planetology.

Short, Nicholas M.↗

Decadal and seasonal changes in barrier island geomorphology at Padre Island from 1950-2020

Barrier islands serve an important role in shielding coastal areas from storm surges and wave erosion. Monitoring changes in a barrier island system helps determine the effect of storms and sea level rise (SLR) on island stability. Changes in geomorphic facies on the islands may be indicators of an island shifting out of an equilibrium state. Here, we used aerial and satellite images of Padre Island, Texas near Mansfield Pass, to map the decadal and seasonal geomorphological changes from 1970-2020. Inspection of the images reveals that this area experienced significant change over the past five decades, transitioning from unvegetated dune fields and sand flats to expansive vegetated dunes and a tidal flat with microbial mats. Vegetated dunes, absent in 1970, now cover 14% of the study area. The active dune field shrunk from 12% coverage to 6%. The infrequently flooded back-island sand flat covering 40% of the study area has transitioned to a lower-lying tidal flat. Extensive microbial mats and crusts have developed within the wind-tidal flat, in washover fans, and in low-lying interdune areas. Possible triggers for the transition from active sand dune fields to microbial mats and vegetation may be modifications to the island topography post-hurricane Allen in 1980 and a sea-level driven water table rise. The local sea level has risen 16 cm over the study period. Monthly mapping over a full year demonstrated the strong influence the seasonal water cycle has on the back-island facies. Aeolian transport plays a primary role in the back-island geomorphology, however the availability of sand for transport is highly variable from month to month as the surface fluctuates in and out of the capillary fringe. The increasing prevalence of water table-driven facies changes leads to the conclusion that back-barrier accretion is not keeping pace with relative SLR. These facies changes may be the first signs of a degrading microtidal barrier island.

K.R. Fisher↗

Investigation of Geomorphological Signatures of Permafrost in the Polar Lunar Areas With VIPER

A study of images of the polar regions shows that small craters near the poles of the Moon are distinguished by the following features: 1. they have a smoother shape - see Fig (a); 2. patterned ground (“wrinkled skin”) is often observed in and around the crater - see Figs (a,b,c); 3. outside the craters landslides and cracks are noticeable - see Fig (d); 4. layers or scarps are often visible on the inner slope - see Fig (e). These features (scarps and patterned ground) are typical for Martian craters in the permafrost zone (see Fig f), as well as for similar zones on Earth. It is hypothesized that these features of lunar craters are associated with the presence of permafrost in the polar regions of the Moon. In 2023, the VIPER rover will investigate the distribution of ice (volatile) deposits in the region of the Moon's South Pole. VIPER navigation cameras represent a unique opportunity for the geomorphological analysis of the lunar surface and the study of physical properties of regolith due to multiple key factors: - A large number of high-quality digital images with a good resolution of the South Pole of the Moon, which is a key region for the landing of manned expeditions. - A low position of the Sun, which generates long shadows, creates favorable conditions for object recognition algorithms. - A presence of a rover track in the images enables VIPER wheels to be used as tools for the study of the regolith and the development of a geotechnical model of regolith in the South Pole region. Rover navigation cameras will allow investigation of the distribution and shape of small craters and other structures along the path of the rover and test the hypothesis about geomorphological signatures of permafrost in the lunar polar areas. If a relationship between characteristics of lunar craters and the distribution of permafrost is confirmed, this will open a possibility to remotely determine the deposits of lunar ice from satellite imagery.

VIPER↗

Wave climate model of the Mid-Atlantic shelf and shoreline (Virginian Sea): Model development, shelf geomorphology, and preliminary results

A computerized wave climate model is developed that applies linear wave theory and shelf depth information to predict wave behavior as they pass over the continental shelf as well as the resulting wave energy distributions along the coastline. Reviewed are also the geomorphology of the Mid-Atlantic Continental Shelf, wave computations resulting from 122 wave input conditions, and a preliminary analysis of these data.

Goldsmith, V.↗

Geomorphology

The study of geomorphology and terrain analysis using TM and MSS data are discussed. The spatial and spectral characteristics of a variety of landforms are also investigated. An outline of possible experiments and a summary of data requirements are included.

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