Deglacial Flood Origin of the Charleston Alluvial Fan, Lower Mississippi Alluvial Valley

1994 ◽  
Vol 41 (3) ◽  
pp. 278-284 ◽  
Author(s):  
Donna A. Porter ◽  
Margaret J. Guccione
Keyword(s):  
Mississippi River ◽  
Alluvial Fan ◽  
Coarse Grained ◽  
Silty Clay ◽  
Mississippi Valley ◽  
Lower Mississippi Valley ◽  
Fine Grained ◽  
The North ◽  
Sand Body ◽  
Braided Stream

AbstractLarge-magnitude flooding of the Mississippi River from proglacial lakes Agassiz and Superior most likely occurred between 11,300 and 10,900 and 9900 and 9500 yr B.P. The Charleston alluvial fan, a depositional remnant of one of these floods, is located at the head of a wide alluvial plain near Charleston, Missouri. The fan is an elongate, convex-up sand body (16 × 24 km) composed of medium- and fine-grained sand at least 8 m thick. This sand contrasts with the older coarse-grained sand of the braided stream surface to the west and south and younger silty clay of the meandering stream level to the north and east. A weakly developed soil separates the underlying braided steam deposits from the alluvial fan. A bulk-soil radiocarbon date of 10,590 ± 200 yr B.P. from the contact between the fan and clays of the meandering stream system indicates that the Charleston fan was deposited near the end of the early interval of flooding from Lake Agassiz about 10,900 yr B.P. If the Charleston fan is the last remnant of deglacial flooding in the lower Mississippi Valley, then deposition of significant quantities of sediment from largemagnitude floods between 10,000 and 9500 yr B.P. did not extend into the lower Mississippi Valley through Thebes Gap.

Origin and physical and chemical characteristics of glacial overburden in Essex and Kent counties, southwestern Ontario

1997 ◽  
Vol 34 (3) ◽  
pp. 233-246 ◽  
Author(s):  
T. F. Morris ◽  
R. I. Kelly
Keyword(s):  
Coarse Grained ◽  
Glacial Lake ◽  
Silty Clay ◽  
Fine Grained ◽  
The North ◽  
Geochemical Properties ◽  
Clayey Silt ◽  
Kent County ◽  
Stratigraphic Position ◽  
Physical And Chemical

The overburden of Essex and Kent counties, southwestern Ontario, has been described as consisting of a clayey silt to silty clay till overlying a gravelly unit resting on bedrock. Recent Quaternary geology mapping has identified additional materials and redefined the origin of others by determining the stratigraphic position and physical and geochemical properties of materials encountered in a sonic drilling program and field mapping. Catfish Creek Till was deposited on the bedrock surface during the Nissouri Stadial as ice advanced south over the area. As ice retreated during the Erie Interstade, fine-grained glaciolacustrine material was deposited in glacial Lake Leverett and overlay Catfish Creek Till. Tavistock Till was deposited over glacial Lake Leverett material as the Huron lobe readvanced south during the Port Bruce Stadial. As the Huron lobe retreated north, coarse-grained glaciolacustrine materials were deposited in the Leamington area. Ice from the Erie lobe deposited the Port Stanley Till along the north shore of Lake Erie in Kent County and deflected meltwater southward from the Huron lobe in the Blenheim area. A series of recessional moraines were deposited by the Huron lobe as it retreated north. The area is capped by a fine-grained glaciolacustrine deposit.

scholarly journals Alluvial architecture of fluvio-deltaic successions: a review with special reference to Holocene settings

2007 ◽  
Vol 86 (3) ◽  
pp. 211-227 ◽  
Author(s):  
M.J.P. Gouw
Keyword(s):  
Special Reference ◽  
Three Dimensional ◽  
Coarse Grained ◽  
Mississippi Valley ◽  
Major Drawback ◽  
Lower Mississippi Valley ◽  
Fine Grained ◽  
Base Level ◽  
Alluvial Architecture ◽  
Active Channels

AbstractAlluvial architecture has been subject of many studies because of the occurrence of natural resources in ancient fluvial successions. This paper provides an overview of the current state of research on alluvial architecture with special reference to Holocene fluvio-deltaic settings. Several examples from modern fluvio-deltaic areas, especially the Holocene Rhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley (U.S.A.), are used to illustrate the architectural elements that can be distinguished in fluvial successions and to show the influence of the various controls on alluvial architecture (base level, climate, tectonism, aggradation, avulsion, and compaction). Avulsion is regarded as a principal process in the formation of fluvio-deltaic sequences, because it determines the location and number of active channels on the floodplain. The avulsion mechanism is still subject of debate, though. A brief description of the evolution of process-based alluvial-architecture models is given. These models simulate the proportion and distribution of coarse-grained channel belts in fine-grained overbank deposits. The major drawback of the present-day alluvial-architecture models is the lack of (three-dimensional) quantitative field data to test and validate them. The paper concludes with the suggestion to collect more architectural data from natural fluvial settings, to improve simulation of channel-belt geometry in alluvial-architecture models, and to implement new data and knowledge of fluvial processes into models.

Meander Loops and the Cahokia Site

1964 ◽  
Vol 30 (1) ◽  
pp. 89-91 ◽  
Author(s):  
Charles J. Bareis
Keyword(s):  
Mississippi River ◽  
River Channel ◽  
River Valley ◽  
Mississippi Valley ◽  
Channel Migration ◽  
Mississippi River Valley ◽  
Lower Mississippi Valley

AbstractThe locations of certain mounds at the Cahokia site indicate that the rate of Mississippi River channel migration in the American Bottoms in the Upper Mississippi Valley has differed from the rate of channel movement in the Lower Mississippi Valley. The American Bottoms was probably the most favorable section of the Mississippi River Valley for long-term prehistoric settlement with regard to location within the present meander belt of the river.

The Archaic of the Lower Mississippi Valley

1961 ◽  
Vol 26 (3Part1) ◽  
pp. 317-323 ◽  
Author(s):  
William G. Haag
Keyword(s):  
Mississippi River ◽  
Gulf Coast ◽  
General Pattern ◽  
Ohio River ◽  
Mississippi Valley ◽  
Eastern United States ◽  
Alluvial Valley ◽  
Lower Mississippi Valley ◽  
General Acceptance ◽  
Poverty Point

AbstractNo archaeological remains which the majority of specialists will accept as Archaic have been found in the Mississippi Valley from the mouth of Ohio River to the Gulf of Mexico. Despite this, the literature reflects a general acceptance of the belief that the Archaic stage is well represented in the Lower Valley. The presence of concentrated Archaic populations in northern Alabama and western Tennessee and Kentucky has given comparative support to these expectations and has provided part of the source for some of the hypothetical statements in the literature of what the Lower Valley Archaic ought to be like. Although the failure of writers to agree on a definition of Archaic which will satisfy the evidence in all of the areas of Eastern United States has contributed to the problem of identifying Archaic materials in the Lower Valley, the lack of these remains can best be explained by the geology of the region. The cutting and filling of the Alluvial Valley during the Pleistocene changes in sea level have removed or buried all of the surfaces that might have been occupied by Archaic peoples. The surface of the Alluvial Valley is everywhere less than 5000 years old. Possible Late Archaic sites are located on old stable beach ridges or near enough to the Pleistocene terraces not to have been included in the general pattern of Recent coastal subsidence. It is concluded that Archaic or earlier materials are absent in the Lower Alluvial Valley of the Mississippi River. Neither Tchefuncte nor Copell are accepted as Archaic; Poverty Point is viewed as transitional from an Upper Archaic tradition to some phase of the Formative stage. Poverty Point materials may not be expected to be found in quantity along the Gulf Coast of the Mississippi Delta region.

Origin of glacial ridges (OIS 6) in the Kaskaskia Sublobe, southwestern Illinois, USA

2012 ◽  
Vol 78 (2) ◽  
pp. 341-352 ◽  
Author(s):  
Nathan D. Webb ◽  
David A. Grimley ◽  
Andrew C. Phillips ◽  
Bruce W. Fouke
Keyword(s):  
Debris Flows ◽  
Spatial Arrangement ◽  
Coarse Grained ◽  
Ice Flow ◽  
Glacial Ice ◽  
Distinctive Features ◽  
Fine Grained ◽  
The North ◽  
Till Fabric ◽  
Glacial Landforms

AbstractThe origin of Illinois Episode (OIS 6) glacial ridges (formerly: ‘Ridged Drift’) in the Kaskaskia Basin of southwestern Illinois is controversial despite a century of research. Two studied ridges, containing mostly fluvial sand (OSL ages: ~ 150 ± 19 ka), with associated debris flows and high-angle reverse faults, are interpreted as ice-walled channels. A third studied ridge, containing mostly fine-grained till, is arcuate and morainal. The spatial arrangement of various ridge types can be explained by a glacial sublobe in the Kaskaskia Basin, with mainly fine-grained ridges along the sublobe margins and coarse-grained glaciofluvial ridges in a paleodrainage network within the sublobe interior. Illinois Episode till fabric and striation data demonstrate southwesterly ice flow that may diverge near the sublobe terminus. The sublobe likely formed as glacial ice thinned and receded from its maximum extent. The Kaskaskia Basin contains some of the best-preserved Illinois Episode constructional glacial landforms in the North American midcontinent. Such distinctive features probably result from ice flow and sedimentation into this former lowland, in addition to minimal postglacial erosion. Other similar OIS 6 glacial landforms may exist in association with previously unrecognized sublobes in the midcontinent, where paleo-lowlands might also have focused glacial sedimentation.

scholarly journals Paleoenvironment and taphonomy of the dinosaur-bearing Ischigualasto Formation (Upper Triassic, Argentina)

1992 ◽  
Vol 6 ◽  
pp. 249-249 ◽  
Author(s):  
Raymond R. Rogers ◽  
Catherine A. Forster ◽  
Cathleen L. May ◽  
Alfredo Monetta ◽  
Paul C. Sereno
Keyword(s):  
Large Scale ◽  
Lower Half ◽  
Coarse Grained ◽  
Fine Grained ◽  
Karoo Basin ◽  
Sand Body ◽  
Faunal Succession ◽  
New Material ◽  
Group A ◽  
Depositional Setting

The oldest-known dinosaurs (Herrerasaurus, Pisanosaurus) occur within the Ischigualasto Formation. Recent work in the formation has brought to light significant new material, including the complete skeleton of a new primitive dinosaur. We sketch below the paleoenvironment and faunal succession during the range of these early dinosaurs, and review some of the taphonomic factors that shaped their fossil record.The Ischigualasto Formation (Carnian?) is included within the Agua de la Peña Group, a series of continental Triassic deposits exposed in the Ischigualasto-Ville Union Basin of northwest Argentina. Ischigualasto sediments rest unconformably upon the carbonaceous fluvial/lacustrine Los Rastros Formation; this contact is characterized locally by marked angular discordance. The upper contact is gradational into red-beds of the Los Colorados Formation. Medium- to coarse-grained conglomeratic sandstones, siltstones, and silty mudstones dominate the section. Sand bodies are characterized by medium- to large-scale trough cross-stratification and broad lenticular/narrow sheet geometries, and are interpreted as deposits of shallow, low-sinuosity streams. Siltstones and mudstones show pervasive evidence of soil development, including root traces, nodular caliche horizons, and pedogenic slickensides. Deposits attributable to lacustrine/paludal sedimentation are scarce, and freshwater vertebrates and invertebrates are extremely rare. These data suggest an upland depositional setting on a low-relief alluvial plain with seasonal climate.The Ischigualasto vertebrate fauna includes archosaurs, rhynchosaurs, traversodontid and carnivorous cynodonts, and temnospondyl amphibians. Rhynchosaurs dominate (relative specimen abundance) in the lower half of the section, but are absent from the upper half. Traversodontid cynodonts occur throughout the formation, but are much more abundant up-section. Archosaurs, carnivorous cynodonts, and particularly temnospondyls are rare throughout, with dinosaurs limited to the lower half. No major stratigraphic or sedimentologic changes occur up-section, and there is no evidence for significant shifts in physical or chemical taphonomic processes. Thus, trends in relative taxon abundance likely record a true biotic signal (e.g., local extinction, immigration) rather than a taphonomically-driven preservational bias.Fossils are preserved as isolated carcasses or disarticulated elements, most often in fine-grained overbank facies. Bone beds and microsites are conspicuously absent. Temnospondyl remains were found within a local carbonaceous lens developed upon a sand body, suggesting autochthonous burial in an abandoned-channel setting. Isolated skulls, particularly those of the traversodontid Exaeretodon, are extremely common. Fifteen isolated crania of this cynodont were mapped in a single stratum with limited areal exposure. Abundant preservation of isolated therapsid crania has also been reported in the Beaufort Series (Permo-Triassic) of the Karoo Basin, South Africa (Smith, 1980). Post-disarticulation hydrodynamic sorting (enhanced by scavenging?) of an areally dispersed mass-mortality assemblage may explain this unusual occurrence.

New Evidence Concerning the Original Order of Deposition of the Longmyndian Rocks

1948 ◽  
Vol 85 (2) ◽  
pp. 107-109 ◽  
Author(s):  
John Challinor
Keyword(s):  
Coarse Grained ◽  
The West ◽  
North West ◽  
The Road ◽  
Fine Grained ◽  
Original Order ◽  
The North ◽  
The Hill ◽  
New Evidence ◽  
The Village

During the war a large new quarry was opened in the Longmyndian rocks of Haughmond Hill, Shropshire. It is near the south-east edge of the hill, to the west of the road running north from Upton Magna and one mile from the village. On the sketch-map in the Shrewsbury Memoir (p. 58) two arrows are shown, at about this locality, recording dips of 50° in a south-easterly direction. I was told that there was a very small quarry here before the large quarry was excavated. The present quarry is even larger than that near Haughmond Abbey (Shrewsbury Memoir, p. 48), on the north-west side of the Pre-Cambrian outcrop, and the two quarries offer extensive and splendidly displayed exposures of Longmyndian rocks, one in the coarse-grained Western Longmyndian and the other in the fine-grained Eastern Longmyndian.

Uncommon preservation of dinosaur footprints in a tidal breccia: Eubrontes giganteus from the Early Jurassic Mongisty tracksite of Aveyron, southern France

2021 ◽  
pp. 1-18
Author(s):  
Jean-David Moreau ◽  
Jacques Sciau ◽  
Georges Gand ◽  
Emmanuel Fara
Keyword(s):  
Scale Up ◽  
Lower Jurassic ◽  
Depositional Environments ◽  
Early Jurassic ◽  
Coarse Grained ◽  
Southern France ◽  
Fine Grained ◽  
The North ◽  
Dinosaur Tracks ◽  
First Time

Abstract A recent excavation yielded 118 large tridactyl footprints in the Lower Jurassic Dolomitic Formation of the Causses Basin, at Mongisty in southern France. Most of the tracks are ascribed to Eubrontes giganteus Hitchcock, 1845. They are preserved on a surface of 53 m2 and form parallel rows with a preferential orientation towards the north. Such an abundance and density of E. giganteus is observed for the first time in the Early Jurassic from the Causses Basin. Sedimentological and ichnotaphonomical analyses show that the footprints were made at different time intervals, thus excluding the passage of a large group. In contrast to all other tracksites from the Dolomitic Formation, where tracks are preserved in fine-grained sediments corresponding to low-energy depositional palaeoenvironments, the tracks from Mongisty are preserved in coarse-grained sediment which is a matrix- to clast-supported breccia. Clasts consist of angular to sub-rounded, millimetric to centimetric-scale (up to 2 cm), poorly sorted, randomly oriented, homogeneous dolostone intraclasts floating in a dolomudstone matrix. Sedimentological analysis shows that the depositional environments of Mongisty varied from subtidal to intertidal/supratidal settings in a large and protected flat marsh. The lithology of the track-bearing surfaces indicates that the mudflat of the Causses Basin was sporadically affected by large mud flows that reworked and redeposited mudstone intraclasts coming from the erosion of upstream, dry and partially lithified mud beds. Throughout the world, this type of preservation of dinosaur tracks in tidal matrix- to clast-supported breccias remains rare.

scholarly journals Automated characterization of ridge-swale patterns along the Mississippi River

2021 ◽  
Author(s):  
Alicia Downard ◽  
Stephen Semmens ◽  
Bryant Robbins
Keyword(s):  
Mississippi River ◽  
Machine Learning Algorithms ◽  
Training Data ◽  
Mississippi Valley ◽  
Lower Mississippi Valley ◽  
Linear Feature ◽  
Topographic Features ◽  
Backward Erosion Piping ◽  
The Individual

The orientation of constructed levee embankments relative to alluvial swales is a useful measure for identifying regions susceptible to backward erosion piping (BEP). This research was conducted to create an automated, efficient process to classify patterns and orientations of swales within the Lower Mississippi Valley (LMV) to support levee risk assessments. Two machine learning algorithms are used to train the classification models: a convolutional neural network and a U-net. The resulting workflow can identify linear topographic features but is unable to reliably differentiate swales from other features, such as the levee structure and riverbanks. Further tuning of training data or manual identification of regions of interest could yield significantly better results. The workflow also provides an orientation to each linear feature to support subsequent analyses of position relative to levee alignments. While the individual models fall short of immediate applicability, the procedure provides a feasible, automated scheme to assist in swale classification and characterization within mature alluvial valley systems similar to LMV.

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