Outwash Deposits Research Articles

Partitioning of Sediments Among Shoreface Transport Paths: Analysis of Sediment Dispersal Patterns Using Empirical Orthogonal Functions: ABSTRACT

Recent geomorphic evidence from the inner shelf and shoreface to the east of Long Island's barrier island system indicates that reworking of glacial outwash deposits at the inner shelf-shoreface transition, as sea level rises, may be supplying much of the sediment needed to maintain barrier islands to the west. A conceptual model describing sediment dispersal from outwash source areas was developed from this hypothesis. It was reasoned that outwash sediments ranging from silts to coarse gravels would be subject to differential transport paths across and along the shoreface upon reworking. Coarser grain sizes would move onshore toward the intertidal beach, whereas finer sediments would move offshore. Sand of intermediate grain size would be concentrated in the surf zone an move alongshore in wave-generated longshore currents. To test this model, 400 samples from the beach and shoreface of Long Island were analyzed for grain-size frequency distribution and each grain-size class was examined for frequency of occurrence in the cross-shore and alongshore directions. On a spatially averaged basis, grain-size classes displayed peak abundance in specific zones across the shoreface as predicted by the model, but alongshore trends could not be recognized among the data. Therefore, empirical orthogonal functions (EOF) were used to examine uncorrelated (orthogonal) modes of variability in the occurrence of each grain-size class in the alongshore direction. The first function, representing more than 60% of the variability among the data, showed that grain sizes subject to longshore transport in the surf zone i crease in frequency in the alongshore direction relative to coarser grain sizes. Results also show that peak concentrations of coarse sediments correspond to zones subject to frequent overwashing. It is concluded that EOF analysis of individual grain-size classes holds promise for extracting trends from noisy data sets. End_of_Article - Last_Page 318------------

Darcian Flow Characteristics Upgradient of a Kettle Pond Determined by Direct Ground Water Flow Measurement

AbstractIn glacial outwash deposits, the movement of ground water Is determined by small scale irregularities in the pattern of hydraulic conductivity. Permeability determinations on split spoon samples obtained from coring the site are not sufficient to predict the patchiness of flow since it cannot define continuity of the strata. The lattice work pattern can be determined by vertical profiling with direct ground water flow measurement. The rate and direction of flow is combined with head gradient changes to compute hydraulic conductivity changes across the site.The results of the tests can be plotted on triangular graphs depicting the fundamental Darcy equation. The local conditions reflect a mathematical “patchiness” of hydraulic conductivity unique to outwash deposits.The procedure was employed to determine flow characteristics and define the zone of contribution to porous bottom kettle lakes. The zone of contribution was defined by projecting backward from the vertical profiling and shallow measurements and taking into account the daily rain water recharge rate across the site.For the unconfined aquifer north of the pond, shallow ground water flow measurements were necessary to define the recharge portion of the shoreline. Vertical profiling was required to define the recharge volume since the rate of flow was not even with depth. A simple differential equation for determining the recharge area is presented along with the calculations.

Early Pleistocene glacial outwash deposits in the eastern San Joaquin Valley, California: a model for humid‐region alluvial fans

ABSTRACT The early Pleistocene Laguna and Turlock Lake Formations and China Hat and Arroyo Seco Gravels along the east side of the San Joaquin Valley, California, were deposited in alluvial fans and marginal lakes. Upward‐coarsening sequences of silt‐sand‐gravel record westward progradation of glacial outwash fans from the Sierra Nevada into proglacial lakes in the San Joaquin Valley. Distinctive sedimentary features delineate lacustrine, prodelta, and delta‐front facies within fan‐margin deposits and lower, middle, and upper‐fan facies within alluvial‐fan deposits.The lacustrine facies consists of a few metres of thinly and evenly bedded, rhythmically laminated claystone and clayey siltstone in varved couplets. Draped lamination, sinusoidal lamination, and load and pillar structures occur in some beds. Siltstone and claystone grade upward to slightly thicker wavy beds of siltstone and very fine‐grained unconsolidated sand deposited in a prodelta setting. Convolute laminae within deformed steeply dipping foreset beds suggest slumping on the prodelta slope. The prodelta facies grades up to the delta‐front facies, which consists of burrowed and bioturbated cross‐bedded fine sand. Deltaic deposits are 5–6 m thick.The lower‐fan facies forms the base of the fan sequence and consists of several metres of irregularly bedded, laminated, oxidized siltstone and fine sand. The middle‐fan facies consists of cross‐bedded, medium‐grained to gravelly sand‐filled channels cut into the lower‐fan facies. Interbedded lens‐shaped siltstone beds 2 m thick and several metres across were deposited in abandoned channels. The upper‐fan facies consists of moderately to strongly weathered clayey gravel and sand containing pebble imbrication and crude stratification. Argillization during post‐depositional soil formation has blurred the distinction between mud‐supported debris‐flow deposits and clast‐supported channel deposits, but both are present in this facies.The deposits described here demonstrate the need for additional fan models in order to incorporate the variety of deposits developed in alluvial fan sequences deposited in humid climates. In previous models based on arctic fans, debris flows, abandoned channels, or widespread siltstone beds are not present in fan sequences, nor are marginal lacustrine and deltaic deposits well represented.

Sedimentary Processes and Buried Ice Phenomena in the Pro-Glacial Areas of Spitsbergen Glaciers

AbstractObservations at the snouts of several glaciers in Spitsbergen indicate that, between their present apparent limits and the moraines dating from the maximum Holocene extent of ice, wide areas of outwash deposits underlain by dead glacier ice occur. Such ice was visible at a number of localities. Indirect evidence of dead ice includes kettle-holes, collapse structures and, in one case, a subglacial melt stream emerging as a fountain within one such plain. Aufeis, formed in early winter, can sometimes also be preserved in the long term if covered by fluvio-glacial material. The presence of such ice has implications for the interpretation of soft-sediment structures in glacigenic successions. Previously, many folds and faults have been interpreted as resulting from active ice overriding or pushing the sediment. Simple ablation beneath the sedimentary layer in question also gives rise to similar structures.

Sedimentary Processes and Buried Ice Phenomena in the Pro-Glacial Areas of Spitsbergen Glaciers

AbstractObservations at the snouts of several glaciers in Spitsbergen indicate that, between their present apparent limits and the moraines dating from the maximum Holocene extent of ice, wide areas of outwash deposits underlain by dead glacier ice occur. Such ice was visible at a number of localities. Indirect evidence of dead ice includes kettle-holes, collapse structures and, in one case, a subglacial melt stream emerging as a fountain within one such plain.Aufeis, formed in early winter, can sometimes also be preserved in the long term if covered by fluvio-glacial material. The presence of such ice has implications for the interpretation of soft-sediment structures in glacigenic successions. Previously, many folds and faults have been interpreted as resulting from active ice overriding or pushing the sediment. Simple ablation beneath the sedimentary layer in question also gives rise to similar structures.

Glaciotectonic origin of the Massachusetts coastal end moraines and a fluctuating late Wisconsinan ice margin

Late Wisconsinan end moraines on Cape Cod and islands south and west of Cape Cod are believed to be glaciotectonic features formed by advancing ice fronts. Evidence of a glaciotectonic origin includes the stratified drift composition of the moraines, dislocated preglacial and glaciolacustrine deposits, tilted preglacial and glacial beds, folding and thrust faulting, and morphologic similarity to ancient and modern glaciotectonic moraines. Evidence for major ice readvances during over-all general recession includes the moraines themselves, till atop stratified drift, and the numerous basal tills that are inferred to exist beneath Cape Cod Bay. The Thompson Glacier end moraine in the Canadian Arctic Archipelago is considered to be a modern example of how late Wisconsinan end moraines on Cape Cod and the islands were formed. The Thompson Glacier is overriding its outwash plain, displacing outwash deposits forward and upward beyond the ice front. New sheets are added to the base of the moraine, and till is deposited atop the moraine as the ice overrides it. Evidence from Cape Cod and the nearby islands indicates that over-all recession of late Wisconsinan ice was characterized by alternating episodes of ice-front retreat, during which the outwash plains were formed, and of ice-front advance, during which the moraines were built. Retreat of the ice from Cape Cod and the islands may have been similar to the retreat of the Lake Michigan lobe, deposits of which contain evidence of at least 12 moraine-building episodes caused by readvancing ice during the over-all retreat of the late Wisconsinan ice sheet.

Late quaternary sediments in Lake Zürich, Switzerland

Lake Zurich occupies a glacially overdeepened perialpine trough in the northern Middlelands of Switzerland. A total of 154.4 m of Quaternary sediments and 47.3 m of Tertiary Molasse bedrock has been cored from the deepest part of the lake, some 10 km south of the city of Zurich. Some 16.8 m of gravels and sands directly overlying the bedrock include basal till and probably earliest subglacial fluvial and lacustrine deposits. These are overlain by 98.6 m of fine-grained, glacial-aged sediments comprising completely deformed proglacial and/or subglacial lacustrine muds, separated by four basal mud tills. The lack of interglacial sediments, fossils, and other datable material, and the presence of severe sediment deformation and unknown amounts of erosion prevent the establishment of an exact chronostratigraphy for sediments older than the upper mud till. Above it some 8.6 m of lacustrine muds were deposited, folded, faulted, and tilted during the final opening of the lake at about 17,500–17,000 years ago. Superimposed are 30.4 m of final Wurm and post-glacial sediments comprising (from oldest): cyclic proglacial mud, thick-bedded and laminated mud, a complex transition zone, laminated carbonate, laminated marl, and diatom-calcite varves. These sediments reflect changing catchment and lacustrine conditions including: glacial proximity, catchment stability, lake inflow characteristics, thermal structure, chemistry, and bed stability. Average sedimentation rates ranged from 11 cm yr−1 immediately after glacier withdrawal, to as low as 0.4 mm yr−1 as the environment stabilized. The lack of coarse outwash deposits separating the fine-grained glaciolacustrine sediments from a corresponding underlying basal till suggests that deglaciation of the deep northern basin of Lake Zurich was by stagnation-zone retreat rather than by retreat of an active ice-front.

Engineering geomorphological investigations of a possible landslide, Killiecrankie Pass, Scotland

Summary Preliminary site investigations indicated the possible presence of a partially degraded landslide along the proposed route of the A9 Perth-Inverness Trunk Road Improvement through Killiecrankie Pass in Scotland. The steep natural topography and the congested nature of the site, with an existing trunk road and railway line, necessitated the design of relatively deep cuttings through the landslide area. To investigate the ground conditions in the area and to enable designs for the cuttings to be prepared, a programme of site investigations was implemented, consisting primarily of engineering geomorphological mapping, seismic refraction surveys and the excavation of trial trenches and pits. The investigation revealed the presence of a sequence of glacial tills, outwash deposits and ancient mudflow deposits overlying a steeply sloping and undulating rock-head. Spring sapping was identified as the only major mechanism controlling natural slope instability. Preliminary designs for the cutting slopes were proposed incorporating the need for extensive drainage of the slopes cut in the glacial deposits. This paper describes the scope of the investigations carried out, the interpretation of the ground conditions and an outline of the approach adopted towards design of the cut slopes.

Depositional features of a late Weichselian outwash fan; central East Jylland, Denmark

Four major sedimentary facies are present in coarse-grained, ice-marginal deposits from central East Jylland, Denmark. Facies A and B are matrix-supported gravels deposited by subaerial sediment gravity flows as mudflows (facies A) and debris flows (facies B). Facies C consists of clast-supported, water-laid gravels and facies D are cross-bedded sand and granules. The facies can be grouped into three facies associations related to the supraglacial and proglacial environments: (1) the flow-till association is made up of alternating beds of remobilized glacial mixton (facies A) and well-sorted cross-bedded sand (facies D); (2) the outwash apron association resembles the sediments of alluvial fans in containing coarse-grained debris-flow deposits (facies B), water-laid gravel deposited by sheet floods (facies C) and cross-bedded sand and granules (facies D) from braided distributaries; (3) the valley sandur association comprises water-laid gravel (facies C) interpreted as sheet bars and longitudinal bars interbedded with cross-bedded sand and granules (facies D) deposited in channels between bars in a braided environment. The general coarsening-upward trend of the sedimentary sequences caused by the transition of bars and channel-dominated facies to debris-flow-dominated facies indicate an increasing proximality of the outwash deposits, picturing the advance and still stand of a large continental lowland ice-sheet. The depositional properties suggest that sedimentation was caused by melting along a relatively steep, active glacier margin as a first step towards the final vanishing of the Late Weichselian icesheet (the East Jylland ice) covering eastern Denmark.

Grain Fabric of Planar Cross-Bedding Formed by Lateral Accretion, Caledon Outwash, Ontario, Canada

Sand-sized grains comprising the planar cross-bedding found in a Late Wisconsinan outwash deposit near Caledon, Ontario, show an obliquely downslope preferred orientation. The average angle of obliquity measured from the downdip direction is about 35°. Such a grain fabric was probably produced by the resultant force of the gravity pull that orients the grains to the dip direction and the lateral traction current of the channel flow which tends to imbricate the grains to the upstream dip. This asymmetric mode of grain fabric was formed during deposition of a laterally accreted outwash bar. Detailed examination of grain fabric makes it possible to distinguish the planar cross-bedding of a micro-deltaic origin from that of other types of bar deposit built either partly or predominantly by lateral accretion.

Geology of Indianapolis, Indiana, United States of America

The engineering geology of Indianapolis, Indiana, is strongly influenced by glacial drift, which covers Marion County with a thickness varying from 10 to 350 ft (3.1 to 106.7 m), averaging 140 ft (42.7 m). Nearly all major structures are supported on spread footings bearing either on overconsolidated Wisconsin till or on dense sand and gravel outwash deposits along White River or Fall Creek. Spread footings supporting high rise buildings (up to 38 stories) in downtown Indianapolis are typically designed for bearing pressures of 8 to 12 kips/ft 2 (3.9 to 5.9 kg/cm 2 ). For the relatively small number of structures supported on deep foundations, pressure-injected footings, auger cast piles and drilled piers are the most common types. The main geologic resources of commercial importance in Marion County are sand and gravel, which are obtained from outwash deposits along major streams, and, to a lesser degree, mined limestone. Ninety-five percent of the water withdrawn by the Indianapolis Water Company is from surface sources, as three water supply reservoirs have been formed by constructing dams across major streams. Recent studies have shown that significant quantities of ground water are available within outwash aquifers along White River and Fall Creek.

Early Diagenesis, Atherton Formation (Quaternary), Northern Indiana: A Guide to Understanding Early Cement Distribution in Nonmarine Sandstones: ABSTRACT

In the area studied, the Atherton Formation accumulated primarily as outwash deposits dominated by trough and wedge cross-bedding. Within sand (86% of deposits; Q77F8L15) and polymictic pebble gravel (14%) units, local cements of calcite (99%) and limonite/hematite (1%) are present. The distribution of these cements was controlled by at least three factors: (1) position within the deposit relative to the land surface, (2) average grain size, and (3) primary stratification. Over 90% of cement zones are within 7 m (23 ft) of the present land surface. Meteoric waters made more acidic by decaying organic material locally dissolved carbonate framework grains. As pore fluids continued to move downward and laterally, cementation occurred. On a second level, higher permeability zones associated with sediment of larger grain sizes was an important factor influencing the location of cementation. Cemented horizons are present in 48% of pebble and sandy pebble gravels (contact and pore lining types) and 17% of sands and pebbly sands (contact, pore lining, and occluded types). Moreover, within sand units primary stratification was a parameter that influenced the location of cementation sites. In wedge cross-bed sets, cement zones parallel inclined laminations; in tr ugh cross-beds, 79% of the cement is concentrated in the lower one-third of bed sets near trough axes or immediately below a trough's basal erosion surface. Cement zones were preferentially developed along internal curved laminations within cross-bed sets. Higher permeability concordant with stratification, the result of excellent sorting and coarser grain sizes within individual sand laminations, primarily controlled cement distribution at this level. Carbonate cements in the Atherton range from a trace to 6 mole % MgCo3 (X = 3.6 mole %) with traces of Fe in 16% of the samples analyzed (205 total analyses). The calcite and Mg-calcite generally form a mosaic of anhedral crystals, although distinct rhombohedra are present in some pores. The source for Mg and Fe is believed related to the dissolution of dolomite and Fe-bearing silicate framework grains. The limonite/hematite cements are present as rare, pore-filling patches. A comparison of the percent of carbonate grains in uncemented sand (X = 10 ± 1%) and within cemented zones (X = 7 ± 1%) of similar grain size indicates an information loss during very early diagenesis on the order of 20 to 30% of the carbonate framework component. Therefore, the original proportion of carbonate framework grains in ancient calcite-cemented sandstones may be greatly underestimated due to grain destruction during diagenesis. End_of_Article - Last_Page 489------------

Complex river terrace development in the Nenana Valley near Healy, Alaska

Research Article| April 01, 1982 Complex river terrace development in the Nenana Valley near Healy, Alaska DALE F. RITTER DALE F. RITTER 1Department of Geology, Southern Illinois University at Carbondale, Carbondale, Illinois 62901 Search for other works by this author on: GSW Google Scholar Author and Article Information DALE F. RITTER 1Department of Geology, Southern Illinois University at Carbondale, Carbondale, Illinois 62901 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1982) 93 (4): 346–356. https://doi.org/10.1130/0016-7606(1982)93<346:CRTDIT>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation DALE F. RITTER; Complex river terrace development in the Nenana Valley near Healy, Alaska. GSA Bulletin 1982;; 93 (4): 346–356. doi: https://doi.org/10.1130/0016-7606(1982)93<346:CRTDIT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A complex sequence of river terraces in the Nenana Valley was examined to determine whether the surfaces were depositional or erosional in origin. Of prime concern was the identification of outwash derived from the Healy (early Wisconsin) and Riley Creek I (late Wisconsin) glaciations.Two terraces were formed during the Healy glacial cycle. The higher level represents the depositional surface of the Healy outwash. The lower level was formed during recession of the Healy ice when approximately 18 metres of that outwash was removed. The erosion was initiated when glacial Lake Moody, dammed behind the Healy moraine, spilled over the drainage divide and began excavation of the Nenana gorge. The surface of Riley Creek [] outwash has been offset by faulting near the gorge mouth. Isolated remnants of that surface stand at different elevations, complicating the correlation of downvalley outwash with the Riley Creek I moraine.The evolution of the Nenana gorge is associated with spasmodic development of erosional terraces throughout post-Healy time as the Nenana River attempted to establish a new equilibrium condition. This erosional trend has been interrupted only by out-wash deposition during episodic expansion of the Riley Creek ice. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Facies Analysis and Paleogeographic Implications of a Late Paleozoic Glacial Outwash Deposit, Bihar, India

ABSTRACT Six interbedded facies are recognized in 60-m-thick, late Paleozoic Talchir strata exposed as a small outlier in Archean metamorphics in Bihar, eastern India. Conglomerate facies which occur as elongate bodies and diamictite dispersed in small isolated blocks are interbedded with medium to coarse, massive, horizontal-bedded to cross-bedded sandstone and fine to medium ripple-laminated sandstone and laminated shale facies. A facies model derived from Markov chain analysis reveals a fining-upward relationship from conglomerate at base through sandstone to shale at top. Conglomerate facies which occur as elongate bodies, massive at base and cross-bedded at top, are similar to those of longitudinal bars of proglacial outwash plains. Small blocks of diamictite enclosed in conglomerate are interpreted as ice-rafted frozen blocks of moraine. Massive, horizontal-bedded to cross-bedded sandstone facies correspond to seasonal channel sand, deposited respectively as flooded channel facies and downcurrent-migrating transverse-to-linguoid bars of braided streams. Fine clastic facies occurring as capping on conglomerate and sandy bars correspond to periods of minimal discharge in protected or abandoned parts of outwash plains. Frequent lateral shifts of braided channel bars in outwash plains may account for the recurrence of fining-upward cycles. The deposition of outwash debris is attributed to meltwater streams following southward retreat of the Talchir ice lobe. The ice lobe, perhaps, developed locally on the highlands of Parasnath hill to the south, but there is also a possibility that it represents the northern limit of the ice lobes that advanced northward across the Damodar Valley Basin.

Stochastic model of flow through stratified soils : J Geotech Engng Div ASCE, V106, NGT6, June 1980, P593–610

The flow through Stratified soils has been analyzed using probability theory. The stratification is represented by a stochastic model composed of two Markov chains. Studies were made on two varved clays and a glacial outwash deposit. Seepage in stratified soils is analyzed by a random flow model. The stochastic model for soil stratification is incorporated in the flow model. Simulation techniques were used to obtain the statistical properties of the permeability of the varved clay and outwash deposits. The mean, variance and autocorrelation functions of permeability were computed and compared with experimental results from a varved clay.

Former sea-levels and ice limits in part of Wester Ross, northwest Scotland

All well-developed fossil marine features along 190 km of the coastline of Wester Ross have been mapped and instrumentally levelled. Glaciated intertidal rock platform fragments are interpreted as interglacial. Some pre-existing high rock platform fragments were considerably modified by Lateglacial marine erosion but others stand above the Lateglacial marine limit. Outside the area covered by the Wester Ross Readvance the marine limit represents an approximately synchronous shoreline corresponding with the culmination of the readvance. This shoreline slopes down towards the NNW at between 0.33 and 0.39 m/km. A relative fall of sea-level as ice retreated from the readvance maximum is demonstrated especially by outwash deposits merging into raised beaches. The Main Postglacial Shoreline is tentatively identified but it is inferred that the Main Lateglacial Shoreline is below present sea-level. The raised marine features are compared with certain modern shore features of the study area as well as with some fossil features elsewhere in Scotland.

POLLEN ANALYSES OF SEDIMENTS FROM LOUGH INE AND BALLYALLY LOUGH, CO. CORK, S.W. IRELAND

SummaryPollen analyses of post‐glacial sediments from the marine Lough Ine and freshwater Ballyally Lough are described.Lough Ine was found to have been formerly a freshwater basin. The oldest sediments, banded clays with no microfossils, were probably glacial outwash deposits. These were overlain by post‐glacial sediments; late‐glacial deposits were missing. By comparison with radiocarbon‐dated diagrams from other sites the marine transgression is tentatively dated at c. 4000 b.p. The lowest sediments from Ballyally Lough can be assigned to Mitchell's zone VI, the Boreal period.The post‐glacial vegetational development of both loughs and the surrounding area is discussed.

Early Devonian (Emsian) fossils from the Lake Haupiri area North Westland

Abstract Boulders containing a well preserved fauna (brachiopods, corals, tentaculitids, crinoids, gastropods, and bryozoans of Early Devonian (Emsian) age are dispersed through outwash and morainic deposits of the Otiran Loopline Formation, and in gravels derived from them, between Lake Haupiri and Nelson Creek, North Westland, New Zealand. The faunas and the matrix suggest derivation from sediments similar to the Reefton Group cropping out in the Reefton district 40 km north of Lake Haupiri. From the distribution of the fossiliferous boulders, the likely source is to the west of Trig. Z, between Lakes Haupiri and Ahaura, where thick morainic deposits may conceal a faulted outlier of Reefton Group sediments.

Stochastic Model of Flow Through Stratified Soils

The flow through Stratified soils has been analyzed using probability theory. The stratification is represented by a stochastic model composed of two Markov chains. Studies were made on two varved clays and a glacial outwash deposit. Seepage in stratified soils is analyzed by a random flow model. The stochastic model for soil stratification is incorporated in the flow model. Simulation techniques were used to obtain the statistical properties of the permeability of the varved clay and outwash deposits. The mean, variance and autocorrelation functions of permeability were computed and compared with experimental results from a varved clay.

Bedform, facies and basin model of ancient glacial deposit: A study based on Talchir (Upper Carboniferous) rocks of Taratanr, Bihar, India

Study of bedforms, facies and associated sedimentary structures in the Talchir rocks of Taratanr Lower Gondwana basin suggests that the basal Talchir Boulder bed was deposited by both ice (moraines and deltaic moraines) and braided streams of glacier derivation (outwash deposit). The overlying sandstone was deposited by ephemeral streams. Six depositional facies related to the bedforms, ripple, dune, bar, plane bed, transverse rib and current crescent, were identified. Data compared with those from modern environments, show excellent correlation with the features of modern glacial outwash plains and modern braided, high-gradient streams. A comparison of the stratigraphy and sedimentology of Talchir rocks from eight Lower Gondwana basins in eastern India suggests that the tentative basin model for Talchir deposition in the Taratanr basin may serve as a basic model for Talchir sedimentation in all the Lower Gondwana basins in eastern India.