Appalachian Piedmont landscapes from the Permian to the Holocene

E.T. Cleaves

Home/Archive/USGS

USGS · 70015399

Appalachian Piedmont landscapes from the Permian to the Holocene

E.T. Cleaves

View original source ↗Export metadata ↓

Abstract

Between the Potomac and Susquehanna Rivers and from the Blue Ridge to the Fall Zone, landscapes of the Piedmont are illustrated for times in the Holocene, Late Wisconsin, Early Miocene, Early Cretaceous, Late Triassic, and Permian. Landscape evolution took place in tectonic settings marked by major plate collisions (Permian), arching and rifting (Late Triassic) and development of the Atlantic passive margin by sea floor spreading (Early Cretaceous). Erosion proceeded concurrently with tectonic uplift and continued after cessation of major tectonic activity. Atlantic Outer Continental Shelf sediments record three major erosional periods: (1) Late Triassic-Early Jurassic; (2) Late Jurassic-Early Cretaceous; and (3) Middle Miocene-Holocene. The Middle Miocene-Holocene pulse is related to neotectonic activity and major climatic fluctuations. In the Piedmont upland the Holocene landscape is interpreted as an upland surface of low relief undergoing dissection. Major rivers and streams are incised into a landscape on which the landforms show a delicate adjustment to rock lithologies. The Fall Zone has apparently evolved from a combination of warping, faulting, and differential erosion since Late Miocene. The periglacial environment of the Late Wisconsin (and earlier glacial epochs) resulted in increased physical erosion and reduced chemical weathering. Even with lowered saprolitization rates, geochemical modeling suggests that 80 m or more of saprolite may have formed since Late Miocene. This volume of saprolite suggests major erosion of upland surfaces and seemingly contradicts available field evidence. Greatly subdued relief characterized the Early Miocene time, near the end of a prolonged interval of tropical morphogenesis. The ancestral Susquehanna and Potomac Rivers occupied approximately their present locations. In Early Cretaceous time local relief may have been as much as 900 m, and a major axial river draining both the Piedmont and Appalachians flowed southeast past Baltimore. The Late Triassic landscape was influenced by rift basin development. Streams drained into a hydrologically closed basin: no through-flowing rivers seem to have been present. A limestone escarpment along the Blue Ridge may have existed as a consequence of a semi-arid climate. The Permian may have been a time of Himalayan-like mountains and mountain glaciers. Streams (and glaciers) generally flowed southwest and west. ?? 1989.

Explore related subjects

Geomorphology Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

E.T. Cleaves. 1989. Appalachian Piedmont landscapes from the Permian to the Holocene. https://pubs.usgs.gov/publication/70015399

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

The influence of riparian zone grazing on channel stability in an arroyo

The introduction of large herds of domesticated grazing animals by European immigrants in the late 19th century is one primary hypothesis used to explain the initiation of arroyo cutting in the American West. But studies designed to quantify the effects of grazing on watershed hydrology and sedimentation have had conflicting results that are often scale dependent. We used a before-and-after study design to examine effects of changes in cattle grazing practices on channel stability in Muddy Creek, an arroyo in the Colorado River headwaters. We digitized 620 meander loop cutoff geometries in the alluvial bottom of Muddy Creek and used meander loop cutoff rate as a broad measure of channel stability. Poisson regression modeling indicated that the change in grazing practices caused an order-of-magnitude decrease in meander loop cutoff rate that was independent of other forcings. Repeat measurements of channel geometry showed a decline in bankfull channel width of about 40% after the changes were implemented. Increases in riparian vegetation density are deduced to be the primary mechanism for the increase in channel stability. Prior to the changes in grazing practices, at least one meander loop cutoff occurred each year, some of which were large enough to create headcuts that scale with the depth of downcutting in this arroyo system. Our analysis demonstrates the profound effects that different grazing practices have on channel stability in headwater arroyo systems, and the potential for grazing animals to initiate a cascade of sediment yields to receiving stream networks.

Colorado, Utah, Wyoming↗

USGS2026

Revisiting the geochronology of late Quaternary marine terraces and uplift rates in coastal Santa Barbara County, California, USA

In several early studies, central California marine terraces between Santa Barbara and Point Conception were interpreted to record sea-level high stands of the last interglacial complex, ∼80 ka to ∼120 ka (marine isotope stage [MIS] 5). These ages and their elevations (∼20 m to ∼45 m) indicate modest rates of tectonic uplift, similar to those from other localities in southern and central California. A recent study, using a combination of luminescence and radiocarbon dating, has challenged the older age interpretations, implying much younger terrace ages, between ∼40 ka and ∼55 ka (MIS 3). From these new ages and a considerably lower sea level during MIS 3, much higher rates of tectonic uplift are inferred. In the present study, new uranium-series ages of terrace corals and amino acid age estimates of terrace mollusks were determined to test these competing interpretations. With the exception of a low-elevation terrace in Isla Vista (near Santa Barbara) that dates to MIS 3, terraces farther west are interpreted to date to MIS 5 and imply tectonic uplift rates of 0.20–0.34 m/kyr. A compilation of data for the region yields a decreasing rate of late Quaternary uplift from east, near Ventura, to west, near Point Conception. This trend is interpreted to reflect a decreasing influence of the processes of compression and crustal shortening south of the Big Bend in the San Andreas fault.

California↗

USGS2025

Toward an efficient framework for remote sensing of river bathymetry: Comparing sensors and algorithms on an inaccessible proglacial river in Alaska

Remote sensing can provide reliable information on river depths and this approach might be particularly valuable in areas that are difficult to survey via conventional field methods. In this study, we assessed the potential to map the bathymetry of an inaccessible proglacial river in Alaska from both aerial orthophotos and a multispectral satellite image. In addition, we evaluated a variety of depth retrieval algorithms with different input data requirements, including some methods that require field measurements of water depth for calibration and other techniques that can be applied even when such field data are not available. These approaches might enable more efficient use of remote sensing methods by resource management agencies. Our results suggest that bathymetric mapping along the turquoise-colored river we examined was not only feasible but highly accurate ( R 2 up to 0.94) for both types of image data. Algorithms that use paired observations of depth and reflectance to train depth retrieval models were the most accurate, with errors on the order of 15%–20% and little or no bias. Alternative techniques based on hydraulic and statistical concepts also led to strong agreement between predicted and observed depths but were more susceptible to systematic biases toward under- or over-estimation of depth. In contrast to clear-flowing streams, bathymetric mapping in this environment was enabled by a direct relationship between the depth and brightness of the water due to scattering by suspended sediment. In selecting an appropriate depth retrieval method, a compromise might need to be reached between the level of field effort invested and the accuracy of the resulting image-derived bathymetry. Standalone software for implementing these techniques is freely available.

Alaska↗