Swamp Deposits Research Articles

HYDROCARBON POTENTIAL OF JURASSIC SOURCE ROCKS IN THE JUNGGAR BASIN, NW CHINA

Jurassic source rocks in the Junggar Basin (NW China) include coal swamp and freshwater lacustrine deposits. Hydrocarbon‐generating macerals in the coal swamp deposits are dominated by desmocollinite and exinite of higher‐plant origin. In lacustrine facies, macerals consists of bacterially‐altered amorphinite, algal‐ amorphinite, alginite, exinite and vitrinite. Coals and coaly mudstones in the Lower Jurassic Badaowan Formation generate oil at the Qigu oilfield on the southern margin of the basin. Lacustrine source rocks generate oil at the Cainan oilfield in the centre of the basin.The vitrinite reflectance (Ro) of coal swamp deposits ranges from 0.5% to 0.9%, and that of lacustrine source rocks from 0.4% to 1.2%. Biomarker compositions likewise indicate that thermal maturities are variable. These variations cause those with lighter compositions to have matured earlier. Our data indicate that oil and gas generation has occurred at different stages of source‐rock maturation, an “early” stage and a “mature” stage. Ro values are 0.4%–0.7% in the former and 0.8%–1.2% in the latter.

Lithofacies succession of maar crater deposits in the Eifel area (Germany)

ABSTRACT Maar craters often contain exceptionally preserved fossils and maar sediments may reflect detailed environmental changes. Volcanosedimentary processes in a Middle Eocene maar crater lake are illustrated by the deposits of Eckfeld Maar in the Tertiary Hocheifel Volcanic Field (Rhenish Massif, Germany). The maar origin of the basin is evident from a circular negative gravity anomaly which indicates a low‐density funnel‐shaped basin filling. From the facies analysis of an Eocene (Eckfeld) and a Pleistocene (Döttingen) maar we develop a lithozone classification for the interpretation of maar sediments: syn‐/post‐eruptive breccias are followed by a fining‐upwards sequence of lacustrine mud with coarse layers and final swamp deposits. From the facies analysis and regional geological data we reconstruct the pre‐ to post‐eruptive history of a maar crater prior to post‐Eocene uplift. These observations can be used for the interpretation of Tertiary and Quaternary maar craters that are ideal fossil and sediment traps.

Rudabánya: A late miocene subtropical swamp deposit with evidence of the origin of the African apes and humans

AbstractRudabánya, a rich late Miocene fossil site in northern central Hungary, has yielded an abundant record of fossil primates, including the primitive catarrhine Anapithecus and the early great ape Dryopithecus. While the affinities of Anapithecus are not clear, Dryopithecus is clearly a great ape sharing numerous characteristics of its dental, cranial and postcranial anatomy with living great apes. Like all Miocene hominids (great apes and humans), Dryopithecus is more primitive in a number of ways than any living hominid, which is probably related to the passage of time since the divergence of the various lineages of living hominids, allowing for similar refinements in morphology and adaptation to take place independently. On the other hand, Dryopithecus (and Ouranopithecus) share derived characters with hominines (African apes and humans), and Sivapithecus (and Ankarapithecus) share derived characters with orangutans, thus dating the split between pongines and hominines to a time before the evolution of these fossil great apes. Pongines and hominines follow similar fates in the late Miocene, the pongines moving south into Southeast Asia from southern or eastern Asia and the hominines moving south into East Africa from the Mediterranean region, between 6 to 9 Ma.

Postglacial sea-level rise and sedimentary response in the Guadiana Estuary, Portugal/Spain border

Abstract The study of sedimentological features, foraminifera and molluscan fauna in samples recovered from four rotary boreholes permitted, after 14 C dating, the first assessment of the post-glacial transgression in Guadiana River Estuary. The Holocene sequence is underlain by coarse sediments from delta fan enclosing continental swamp deposits dated 16 980 year BP. The Holocene sedimentary sequence was deposited either directly on this delta fan gravels or on top of fluvial sands deposited probably between 11 000 and 10 000 yr BP. An accelerated phase of the estuary infilling by clayey sediments containing the salt marsh foraminifer Trochammina , began ca. 9800 year BP, when sea level was about 39 m below present. Between 7500 and 7000 year BP, the central part of the estuary started to accommodate coarser sediments, partially introduced from the continental shelf. The first phase of Holocene sea-level rise at a rate of 0.85 m/century terminated ca. 6500 year BP. Since then, lagoonal sediments in the vicinity of the estuary have been enclosed behind sand spits and predominantly sandy sedimentation was initiated within the estuary. After a second phase of slower rise at the rate of 0.3 m/century, which lasted until ca. 5000 year BP, the sea approached the present level.

Late Quaternary tropical lowland environments on Halmahera, Indonesia

Results of a case study of landform development and sedimentation in humid tropical lowland environments on Halmahera island, eastern Indonesia, are presented with the aim to better characterise tropical lowland environments in the context of Late Quaternary environmental change studies. First, the geologic, morphologic and environmental settings of the two areas, the interior Kao River plain and the Kao coastal zone (N. Halmahera), are presented. Subsequently, data concerning Late Pleistocene and Holocene landform development, sedimentation and coastal processes are discussed. Pleistocene landform development involved volcaniclastic sedimentation, base levelling of coastal lowlands, prolonged weathering and crust formation, coastal uplift and eustatic sea level change. A conspicuous ferricrete crust in the subsoil of the coastal plain is tentatively dated with 14C AMS analysis and isotopes of organic matter encapsulated in the soil ferricrete have been determined. Due to interacting sea level change, neotectonic uplift, climatic, hydrologic and vegetational change, unequivocal evidence for anomalous Late Pleistocene or Holocene environmental conditions is difficult to obtain. During the Mid-Late Holocene, a low-energy fluvial systems and swamps existed in the interior Kao River plain; a dense open swamp/swamp forest vegetation contributed to extremely high sedimentation rates in this depositional basin. Palynological analysis of the organic swamp deposits indicates little or no change in sedimentary environmental settings and swamp vegetations, and indications for early human presence in the area. In the coastal area accretion and delta progradation occurred after the Early-Mid Holocene formation of a marine erosion cliff. Tentative evidence for early human presence in the Kao area is derived from charcoal particle frequencies in sediments and the existence of natural grasslands in the coastal zone. As most of the geologic and environmental characteristics of the tropical lowlands in the Kao area are common in eastern Indonesia, the study provides useful information for ongoing research in the region.

Mangrove dynamics in the Rivières du Sud area, West Africa: an ecogeographic approach

Because of the diversity of its mangrove environments, the extensive estuarine coast of West Africa, between Saloum (Senegal) and Sherbro (Sierra Leone) estuaries, provides the biogeographer with a highly favourable framework for the analysis of changes in mangrove communities. These changes can be studied at various organization levels of the mangrove ecosystem, emphasizing the multi-dimensional nature of successional processes. Although being denied elsewhere, the efficiency of biotic processes is demonstrated by numerous case studies relating changes in mangrove communities to simultaneaous edaphic modifications. More recently, disturbances in zonation patterns related to reduction of water discharges draws attention to the fact that varying longitudinal gradients, involving interaction between salt- and freshwater, may give rise to specific successional schemes. Last but not least, how mangroves develop to an equilibrium between deposition in swamp and erosion in the tidal creeks can be appreciated by recognition of a third volumetric dimension of successional processes. Since any successional pattern involves these three dimensional components, an attempt is made to recognize basic `multi-dimensional' sets of process variables, related to the characteristic depositional settings of the area. As a general rule, it can be stated that successional patterns are all the more dependant on varying environmental gradients since they occur in areas receiving large supplies of allochtonous sediments, either from landward (deltaic estuary) or seaward (tidal bay) origins.

Palaeoenvironmental Reconstruction of Zoige Basin of Eastern Tibetan Plateau During the Past 140 ka

The Tibetan Plateau plays a major role on modern atmospheric circulation of Northern Hemi- sphere, especially with respect to the Tropical Easterly Jet and monsoon circulation. Understanding the past climate in the plateau, especially during the late Pleistocene when the Tibetan Plateau uplifting accelerated, will be very important. A 310m core(RM) (33°57′N, 102°21′E) collected from the central part of Zoige Basin, east Tibetan Plateau was analyzed. The upper 31m provide a continuous palaeoclimate information in the past 140ka, which is reconstructed on the basis of stable isotope analyses (δ~(18) O and δ~(13) C of authigenic carbonate), content of carbonate, organic matter and pollen, etc. The results reveal significant changes of palaeoenvironmental condition, induced by climate changes and/or local hydrological factors. Five stages are identified. Stage 5 (140 - 82kaBP) equivalent to Last Interglaciation was warm and wet. The primary productivity was high due to the optimum associaton of heat and moisture. 5 substages (5a - 5e) can be divided, moreover, 5c can be further divided into 5 subordinate substages (5e_1 - 5e_5 ). In the record, 5e is the warmest substage among them, while 5a is the optimum, and 5c is a weakly warm period. A series of cooling events have been recorded since stage 4 (82 - 10kaBP). i. e. 66, 51. 5, 33, 28, 21 kaBP, equivalent to H6, HS, H4, H3, H2 event reported in deep-sea sediment. Comparison study has been done for the RM core record with the other records adjacent and in the world. The result also shows that the stage 3 was a conspicious period, when the climate was very optimum. The basin was cut off by the Yellow River ca 30kaBP, correspondingly the lacustrine deposits were replaced by fluvial and swamp deposits.

The character and age structure of valley fills in upper Wolumla Creek catchment, south coast, New South Wales, Australia

Extensive valley fills at the base of the escarpment in upper Wolumla Creek, on the south coast of New South Wales, Australia, have formed from a combination of ‘cut and fill’ processes. The valley fills comprise series of alternating, horizontally bedded sand and mud units, reflecting reworking of detritus from deeply weathered granites of the Bega Batholith. Sand units are deposited as sand sheets or splays on floodplain surfaces or in floodouts that form atop intact valley fill surfaces downstream of discontinuous gullies. Alternatively, sands are deposited from bedload and form bars or part of the valley floor within channel fills. Organic-rich mud units are deposited from suspension in swamps or in seepage zones at the distal margin of floodouts. Within 5 km of the escarpment, valley deposits grade downstream from sand sheet and splay deposition in floodouts, to mud deposition in swamp and seepage zones. Radiocarbon dates indicate that virtually the entire valley fill of upper Wolumla Creek was excavated prior to 6000 years BP. Remnant terraces are evident at valley margins. The valley subsequently filled between 6000 years BP and 1000 years BP producing valley fills around 12 m deep, but no greater than 300 m wide. Reincision into the valley fill, on a scale smaller than the present incision phase, is indicated at around 1000 years BP, following which the channel refilled. Portion plans dated from 1865 refer to the study area as ‘Wolumla Big Flat’, and show large areas of swampy terrain, suggesting that the valley fill had re-established by this time. Within a few decades of European settlement the valley fill incised once more. Upper Wolumla Creek now has a channel over 10 m deep and 100 m wide in places, draining a catchment area of less than 20 km2. © 1998 John Wiley & Sons, Ltd.

The character and age structure of valley fills in upper Wolumla Creek catchment, south coast, New South Wales, Australia

Extensive valley fills at the base of the escarpment in upper Wolumla Creek, on the south coast of New South Wales, Australia, have formed from a combination of ‘cut and fill’ processes. The valley fills comprise series of alternating, horizontally bedded sand and mud units, reflecting reworking of detritus from deeply weathered granites of the Bega Batholith. Sand units are deposited as sand sheets or splays on floodplain surfaces or in floodouts that form atop intact valley fill surfaces downstream of discontinuous gullies. Alternatively, sands are deposited from bedload and form bars or part of the valley floor within channel fills. Organic-rich mud units are deposited from suspension in swamps or in seepage zones at the distal margin of floodouts. Within 5 km of the escarpment, valley deposits grade downstream from sand sheet and splay deposition in floodouts, to mud deposition in swamp and seepage zones. Radiocarbon dates indicate that virtually the entire valley fill of upper Wolumla Creek was excavated prior to 6000 years BP. Remnant terraces are evident at valley margins. The valley subsequently filled between 6000 years BP and 1000 years BP producing valley fills around 12 m deep, but no greater than 300 m wide. Reincision into the valley fill, on a scale smaller than the present incision phase, is indicated at around 1000 years BP, following which the channel refilled. Portion plans dated from 1865 refer to the study area as ‘Wolumla Big Flat’, and show large areas of swampy terrain, suggesting that the valley fill had re-established by this time. Within a few decades of European settlement the valley fill incised once more. Upper Wolumla Creek now has a channel over 10 m deep and 100 m wide in places, draining a catchment area of less than 20 km2. © 1998 John Wiley & Sons, Ltd.

Sedimentological, Taphonomic, and Climatic Aspects of Eocene Swamp Deposits (Willwood Formation, Bighorn Basin, Wyoming)

Sedimentological, Taphonomic, and Climatic Aspects of Eocene Swamp Deposits (Willwood Formation, Bighorn Basin, Wyoming)

Sedimentological, taphonomic, and climatic aspects of Eocene swamp deposits (Willwood Formation, Bighorn Basin, Wyoming)

Alluvially deposited carbonaceous beds are a major source of leaf compression fossils, but the accumulation of both the sediments and the fossils is poorly understood. We have studied the sediments and fossil plant assemblages of three laterally extensive carbonaceous beds from the Eocene of the Bighorn Basin, Wyoming. Field, laboratory, and microscopic observations show that carbonaceous beds are highly heterogeneous, varying in the amount and type of organic matter, preservation of primary sedimentary structures, and the prevalence of paleosol features. Small-scale lateral and vertical variations indicate a mosaic of conditions in the wet floodplain backswamp. The variables controlling this mosaic were primarily rate of clastic input and degree of substrate flooding which, in turn, influenced the amount of pedogenesis. Fossil plant assemblages occur in sediments least modified by pedogenesis, and the best preservation is in the distal, fine-grained portions of overbank flood deposits. There is no evidence for transport of plant material from channel to backswamp. Fossil leaves in a single quarry sample (i.e., those collected from within 10-20 cm stratigraphically and from an area of 4-10 m 2 ) probably accumulated during one or several closely-spaced flood events. Quarry samples are thus spatially and temporally constrained snapshots of the vegetation that grew on the alluvial floodplain. Each carbonaceous bed is estimated to represent roughly 2,000 years, based on the length of fluvial avulsion cycles. Multiple quarry samples from the same carbonaceous bed can thus be considered coeval for most evolutionary or paleoclimatic analyses. In the central Bighorn Basin, laterally extensive carbonaceous beds are abundant in the lower and upper Willwood Formation, but essentially absent in the middle. We attribute this to tectonic and climatic change, especially to higher rates of sediment accumulation that caused greater dispersal of organic material within sediments and climatic drying that allowed degradation of organic material before it could be preserved.

Taxonomy and palaeoecology of Early Cretaceous (Late Albian) angiosperm leaves from Alexander Island, Antarctica

Seven species of angiospermous leaves from the mid to Late Albian of Alexander Island, Antarctica provide further evidence of angiosperm radiation into high southern palaeolatitudes. The leaves have both palmate (three species) and pinnate (four species) venation. Entire margined leaves with brochidodromus venation are interpreted as belonging to the Magnoliidae, and possibly include members of the Laurales. Palmately veined forms representing the Laurales occur as do palaeoherbs. Other taxa have marginal teeth comparable to those found in the Rosidae. Palaeoecological analysis indicates that Hydrocotylophyllum alexandri sp. nov. was a herbaceous streamside coloniser; Gnafalea jeffersonii gen. et sp. nov. was a small shrubby plant growing adjacent to levee banks. The other angiosperms, Araliaephyllum quinquelobatus sp. nov., Timothyia trinervis gen. et sp. nov., Gnafalea binatus sp. nov., Ficophyllum palustris sp. nov., Dicotylophyllum lobatus sp. nov., occur infrequently in swamp deposits and probably represent a scattered understorey of trees and shrubs amongst a conifer and pentoxylalean overstorey.

The Eastern Chenier Plain: An Update on Downdrift Coastal Progradation Associated with the Building of a New Holocene Delta Lobe in the Mississippi Delta Complex: ABSTRACT

The Eastern Chenier Plain: An Update on Downdrift Coastal Progradation Associated with the Building of a New Holocene Delta Lobe in the Mississippi Delta Complex: ABSTRACT

A Late Pleistocene and Holocene pollen record from Lake Terang, Western Plains of Victoria, Australia

Abstract Analyses of pollen and charcoal from lake and swamp deposits accumulated in a maar crater are used to reconstruct palaeoenvironments at and around Terang, Western Victoria. Changes in the nature of the sediments and in aquatic and dryland pollen indicate substantial climatic variation within the recorded period. Pollen assemblages indicate changes from open woodland, herbfield and grassland to wet sclerophyll forest, and from ephemeral swamp to permanent lake and swamp conditions within the basin. A possible timescale for the Lake Terang sequence is inferred from comparison with the better dated, nearby Lake Wangoom sequence and with the deep sea core record. The Terang record is considered to span a large part of the last glacial period and the Holocene, extending the available record of past vegetation and environments from the region by some 25,000 years to around 75,000 yr B.P. Conditions during the earlier part of the last glacial period were cooler and drier than today with open Casuarina woodland predominating in the region. At times, particularly towards the end of this period, conditions are considered to have been more extreme as much of the pollen is oxidised. A major interstadial, whose termination is tentatively dated at about 48,000 yr B.P. was dominated by Eucalyptus forest under effective precipitation levels similar to those of today. The latter part of the last glacial period is considered to have been cold and dry although no pollen is preserved except during a short phase of amelioration, probably around 39,000 yr B.P. The Holocene has been characterised by mixed Casuarina and Eucalyptus woodland and forest until recent changes brought about by European people. Fire has been a constant feature of the environment and its influence on changing vegetation patterns cannot be determined with certainty.

Palynology and palaeoclimatic implications of two Holocene sequences from southwestern Australia

Results from two palynological investigations of Holocene lake and swamp deposits from southwestern Western Australia are presented. These are used to assess the validity of the existing palaeoclimatic evidence for Holocene climates, which is contradictory. The Boggy Lake sequence from the far southwest of Western Australia shows that, while vegetation changes have taken place over the last ca. 4500 years, these cannot be attributed to climatic change. Palaeoecological interpretations of earlier work at the site are shown to have an insecure basis. The Loch McNess Swamp sequence from further north shows only minor vegetation changes since ca. 9000 yr B.P. which cannot be attributed with certainty to climatic causes. The investigations do not support earlier claims of Mid-Holocene climates wetter than present or of an extensive arid phase in the Mid- to Late-Holocene.

Contrasting Holocene sedimentary geologies of lower Daly River, northern Australia, and lower Sepik-Ramu, Papua New Guinea

The estuarine plain of the macrotidal Daly River, in monsoonal northern Australia, is underlain by extensive mid-Holocene mangrove swamp sediments which accumulated during the last stages of Post-glacial sea-level rise. Sediment yield from the catchment is too low to account for the volume which accumulated during sea-level rise, and onshore transport is invoked. This is supported by radiocarbon ages and facies analysis of the transgressive sediment tract beneath the maximum flooding surface (MFS), and of the tract of vertical sedimentation which extends from the MFS to the surface of estuarine/fluvial transition (the EFT). The EFT occurred about 5000 to 6000 BP throughout the estuarine plain. A contrasting situation exists in the lowland Holocene basin of the microtidal Sepik and Ramu rivers in Papua New Guinea, which derive sediment from highly tectonic catchments. A tectonic basin, which was a shallow brackish inland sea after Post-glacial transgression, is separated by a low divide from a deltaic plain. Progradation of the deltaic plain commenced about 3500 BP after regressive sedimentation eclipsed the inland sea in the tectonic basin. Contrasting organic facies, mangrove in the Daly and freshwater swamp deposits in the Sepik-Ramu, highlight differences between facies models of the two systems. Differences between fluvio-tidal regimes are reflected by the EFT, which is synchronous in the Daly and diachronous in the Sepik-Ramu, and possibly by the MFS which is diachronous in the Daly and may be synchronous in the Sepik-Ramu.

High Resolution Biostratigraphy of Oligo-Miocene Leon and Chama Formations: An Integrated Approach for Sequence Stratigraphy Analysis

Based on foraminiferal and palynological high resolution studies, a set of Sequence Boundaries (SB) and Maximum Flooding Surfaces (MSF) were identified for the Venezuelan Northwestern Andean Foothills Leon and Chama formations. Changes in abundance patterns of forminifera palynomorphs, in faunal/floral composition and distribution, together with quantitative studies of particulate organic matter allowed picking SB 30, 21 and 15.5 (very low values of fossil abundance and faunal discontinuities, recognized by a rapid stratigraphic change in biofacies and faunal assemblage and the associated mineralogical contents) and MFS 18.5, 16, and 15 (abundant fossils). The Leon Formation represents coastal plain and swamp deposits with some minor fluctuations in the seawater level. The top of the Leon Formation shaly unit is bounded by SB 30, according to Hag B.U. et al (version 1992), marked by a decrease in fossil abundance. An increase in faunal/floral content close to the top of the section coincides with the MFS 18.5. The upper part of the formation is marked by a sandy unit with SB 16.5, characterized again by a decrease in fossil abundance at its top. The Chama Formation was deposited in a transitional environment, with minor seawater level fluctuations. Climate type was tropical humid, with seasonalmore » precipitations, except at the Early Miocene arid or semiarid phase. Mangrove and rain forest vegetation dominated throughout the Early to Middle Miocene. MFS 16 was picked on the basis of a high abundance of microforams and glauconite.« less

Single Well Multidisciplinary Facies Reconstruction (De Lutte-6, Upper Carboniferous, Netherlands)

De Lutte-6 is a key well situated in onshore Netherlands. A cored lithological sequence from the Upper Carboniferous has been investigated by means of palynology, palynofacies, paleobotany, and sedimentology. Paleobotanical data suggest a late Westphalian C to late Westphalian D Age. Palynological assemblages have a late Westphalian D-Stephanian character. This discrepancy suggests that the local paleobotanical remains allow for a more precise age determination, whereas the palynological data provide information about the regional facies development. Palynofacies analyses combined with palynoflora data indicate a gradual transition from a waterlogged flood plain characterized by a diverse lycopod/cordait palynoflora, to well-drained flood plain with an impoverished cordait/conifer palynoflora. The sedimentological data, combined with the palynological and the paleobotanical data, suggest that the flood plains alternate with swamp and lake deposits. The transition from a waterlogged flood plain to a well-drained flood plain coincides with transition from intervals characterized by seat-earth soils (indicating humid conditions) to intervals characterized by immature calcie soils (witnessing semihumid to semi-arid conditions).

Holocene vegetation history of Flinders Island

summaryTwo swamp sites on Flinders Island in Bass Strait provide evidence of vegetation cover for the period 10000 BP to present. Steppe vegetation in which Compositae Liguliflorae taxa and chenopods were important was present on the Flinders Island part of the Bassian Isthmus during the earliest part of the record. However, it was replaced by eucalypt forest or woodland with a grassy understorey and some shrubs as sea level rose to form the present island by 6000 BP. The eucalypt dominated vegetation became less important about 940 BP when Callitris became prominent until very recently. This change may be related to a drier climate.Flinders Island is one of the few sites in Australia where humans were absent for an extended time (c. 4700 to 200 BP) during the Holocene. There is no particular indication of pollen or charcoal changes which can be related to the disappearance of humans from the island. However, at Killiecrankie Swamp the arrival of Europeans 200 yr ago probably caused the increased charcoal input to the swamp sediments and the vegetation change observed. Likewise Middle Patriarch Swamp records changes due to clearing and swamp drainage in the most recent times. The fact that the swamp deposits contain charcoal and pollen, together with the density of swamps on the eastern side of the island means the area is very favourably placed to provide detailed information on firing regimes unaffected by humans, in a sclerophyll vegetation very similar to that in large areas of southeastern Australia.In the light of the pollen evidence from this study and that from other southeastern mainland and Tasmanian sites it is suggested that the apparent prominence of Casuarina in the southwest of Victoria and southeast of South Australia during the early Holocene was due to local soil factors and drier climate. Later changes in soil and climate led to a decrease in Casuarina and increase in Eucalyptus.

Discrimination of Kaolinite Varieties in Porters Creek and Wilcox Sediments of North-Central Mississippi

AbstractUse of a discriminant analysis has verified and grouped three suspected varieties of kaolinite found in kaolin-rich clay strata of late Paleocene to early Eocene age across north-central Mississippi. Initial identification of each type of kaolinite was based on clay-texture characteristics observed on scanning electron micrographs and the differences in pattern configurations of X-ray diffractograms. The discriminant function used for data treatment clearly segregated and grouped each variety. The discrimination variables were found to be the Hinckley index and, to a lesser extent, the Si4+ content relative to the Al3+ content.The oldest variety is the Blue Mountain clay, composed of preserved hexagonal plates usually clustered into booklets with a vermiform texture. The Ashland variety, stratigraphically younger than the Blue Mountain clay, appears to have been derived from the erosion of the Blue Mountain clay. The Ashland cannot be recognized by any type of diagnostic texture, as it is made up of individual plates that have been corroded and abraded to the point where a hexagonal outline can no longer be recognized. The Sardis variety is the stratigraphically youngest of the three varieties and is at least a second, or possibly a third generation detrital product. The Sardis clay can be recognized by a distinct “ribbon” or “swirl” texture commonly found in ball clays.Data from this study are not sufficient for complete petrogenetic interpretation. However, speculation on possible differences in depositional environments and modes of deposition can be based on the data at hand. The Blue Mountain variety is considered from previous studies to be primary. The Ashland variety is probably a first generation alluvial clay. The Sardis variety appears to be a multiple generation, detrital product that accumulated as part of overbank swamp deposits.