Showing papers in "Geomorphology in 1989"

TL;DR: In this article, the authors show that the central Appalachian Highlands were tectonically uplifted, intensely weathered, and rapidly eroded three times since the Late Triassic: (1) Early to Middle Jurassic (Aalenian to Callovian); (2) mid-Early Cretaceous (Barremian); and (3) Late Cenozoic (Middle Miocene).

TL;DR: In this paper, the authors interpret the flatness of the Appalachian Piedmont to be the result of three active processes: volume reduction during compaction of saprolite into soil, loss of mass in dissolved solids draining the soil B-horizon, and loss from the soil surface by erosion of clay-size particles.

TL;DR: The marine 18 O record indicates that the first ice advance into the Appalachians equivalent to that of the late Wisconsin occurred in the Pliocene at about 2.4 Ma as discussed by the authors.

TL;DR: Gully networks developed on coastal hillslopes in San Mateo County, California, extended nearly 300% from 1941 to 1978, primarily by subsurface erosion as mentioned in this paper, which expanded the gully network by 80 m.

TL;DR: In this article, the parent material (calcareous material) is a determining factor affecting the genesis of the Spodosols and Histosols, while climate (frigid soil temperatures) and vegetation (conifers) are the major soil forming factors.

TL;DR: In this article, apatite fission-track apparent ages and track length distributions for ash bed samples from the Allegheny Front and Allegheny Plateau of Pennsylvania suggest that these regions represent different thermal (uplift) regimes as well as different structural provinces.

TL;DR: In this article, the authors apply the Monte Carlo method of parameter selection to estimate the topography of the Early Permian central Appalachians by first obtaining the steady-state mass of the wedge from a flexural loading model of Beaumont and others.

TL;DR: In this article, the role of catastrophic geomorphic events in landscape evolution is evaluated, including their contributions to denudation and formation of prominent landscape features, and how they vary through space and time.

TL;DR: In this article, the hydrodynamic environment associated with boulder berm deposition at flow expansions during high-magnitude flood is considered with respect to the plan geometry of surveyed berms.

TL;DR: A series of climate model simulations are utilized to examine the climate evolution of the Appalachians from the Carboniferous to the Present through consideration of large scale changes in paleogeography and potential variations in carbon dioxide on long time scales.

TL;DR: In this paper, landscapes of the Piedmont are illustrated for times in the Holocene, Late Wisconsin, Early Miocene, Early Cretaceous, Late Triassic, and Permian.

TL;DR: Davis' theory of the origin and development of the Folded Appalachian Drainage as discussed by the authors is a landmark in the history of geomorphology and has been used extensively in geomorphic research.

TL;DR: In this article, it was shown that strong winds and their accompanying solid material may cause stresses to the rock in three ways: the direct pressure of the wind and material, the hammering effect of the particles, and by preventing the closure of cracks opened by other forces.

TL;DR: Gold placers are formed as a result of surficial processes but glacial and fluvioglacial systems are generally considered to be unfavourable for placer genesis.

TL;DR: In this article, an extensive body of geologic data including the modern state of stress, historical seismicity, surface and subsurface stratigraphy, numerical models of crustal deformation, surficial geomorphic systems, and historical precise leveling and tidal gauge records constrain the style and rate of neotectonic deformation for the Appalachians and Atlantic passive continental margin.

TL;DR: In this paper, it is assumed that some major landforms not easily explained by surface geology could be controlled by deep crustal properties, and the concept was first applied in the British Isles and then to the U.S. Atlantic provinces.

TL;DR: The origin and evolution of transverse drainage were stumbling blocks to classical, historical geomorphologists, and many problems still remain this article, such as: post-Alleghanian tectonic effects, rates and timings of uplift, erosion and deposition, whether lithotectonic weaknesses are most pronounced in gap areas, and establishing a numerical chronology for drainage development.

TL;DR: In this paper, the Juniata River gauging station at Newport, Pennsylvania was used to calculate a present erosion rate of 27 m Myr−1. The amount of sediment collected at this station was then used to determine the total amount eroded from the 8687 km2 drainage basin during the water years 1965-1986.

TL;DR: In this paper, a conceptual model of till emplacement based on the observed presence of karstic limestone is proposed, which invokes drainage of water from the base of the ice sheet as it advanced on to karstified Palaeozoic limestones from the Precambrian shield.

TL;DR: In this article, the authors describe how mass movement is dissecting a relict alluvial fan at the margin of the margin Sele Valley graben in southern Italy and demonstrate that neotectonics, rather than pseudo-gravitational faulting, are responsible for the distinctive morphology of the fan as mass movement continues to dismatle it.

TL;DR: In this paper, it is proposed that the term anteconsequent, previously used in the context of orogenesis and erosion, should be extended to cover the situation described on the Lyttelton Volcano.

TL;DR: Gardner and Sevon as mentioned in this paper used a computer model to represent the stochastic effects of geomorphic processes acting on Appalachian structures, and to produce the various stages of Cenozoic Appalachian geomorphic history.