Inland Deposits Research Articles

A close relative of the Amazon river dolphin in marine deposits: a new Iniidae from the late Miocene of Angola.

BackgroundA few odontocetes (echolocating toothed cetaceans) have been able to independently colonize freshwater ecosystems. Although some extant species of delphinids (true dolphins) and phocoenids (porpoises) at least occasionally migrate upstream of large river systems, they have close relatives in fully marine regions. This contrasts with the three odontocete families only containing extant species with a strictly freshwater habitat (Iniidae in South America, the recently extinct Lipotidae in China, and Platanistidae in southeast Asia). Among those, the fossil record of Iniidae includes taxa from freshwater deposits of South America, partly overlapping geographically with the extant Amazon river dolphin Inia geoffrensis, whereas a few marine species from the Americas were only tentatively referred to the family, leaving the transition from a marine to freshwater environment poorly understood.MethodsBased on a partial odontocete skeleton including the cranium, discovered in late Miocene (Tortonian-Messinian) marine deposits near the estuary of the Cuanza River, Angola, we describe a new large iniid genus and species. The new taxon is compared to other extinct and extant iniids, and its phylogenetic relationships with the latter are investigated through cladistic analysis.Results and DiscussionThe new genus and species Kwanzacetus khoisani shares a series of morphological features with Inia geoffrensis, including the combination of a frontal boss with nasals being lower on the anterior wall of the vertex, the laterally directed postorbital process of the frontal, the anteroposterior thickening of the nuchal crest, and robust teeth with wrinkled enamel. As confirmed (although with a low support) with the phylogenetic analysis, this makes the new taxon the closest relative of I. geoffrensis found in marine deposits. The geographic provenance of K. khoisani, on the eastern coast of South Atlantic, suggests that the transition from the marine environment to a freshwater, Amazonian habitat may have occurred on the Atlantic side of South America. This new record further increases the inioid diversity during the late Miocene, a time interval confirmed here as the heyday for this superfamily. Finally, this first description of a Neogene cetacean from inland deposits of western sub-Saharan Africa reveals the potential of this large coastal area for deciphering key steps of the evolutionary history of modern cetaceans in the South Atlantic.

Tsunami inundation, sediment transport, and deposition process of tsunami deposits on coastal lowland inferred from the Tsunami Sand Transport Laboratory Experiment (TSTLE)

The processes of tsunami inundation, sediment transport, and deposition on coastal lowlands are investigated experimentally. We conducted large-scale experiments with land slopes of 0.00 and 0.01 and compared them with experiments conducted previously with a slope of 0.02. The ratio of marine-originated sediment in the inland deposits decreased as the land slope decreased, reflecting the strong inundation flow and weak return flow. The sediment concentration near the bed increased remarkably and supplied a greater quantity of coarse sand inland when the land slope decreased, indicating the strong influence of land slope on bed load. The extent of sandy deposits and the inundation limit nearly corresponded with the sloping topographies. However, the inundation flow reached much farther inland than the sandy deposits on the flat (i.e., level) topography. This was because the extent of sandy deposits was determined by the flow speed, which depended in turn on the wave speed, whereas the inundation limit was determined by the inland water mass, which depended in turn on the waveform. The floating load reached the inundation limit and formed very thin and sparse muddy deposits. Considering the uncertainty of the waveform and the difficulty of detecting muddy deposits, it is more feasible to estimate the wave speed from the extent of sandy deposits. The spatial distributions of sandy deposits for various waves, land slopes, and topographies were characterized by the nondimensional area density and inundation distance. This result suggested the possibility of quantitative comparison among field investigations of tsunami deposits under various conditions. The formation of an inverse grading layer, experimentally observed in a wide range of inland deposits, was attributed to kinetic sieving. The bed load under slow deposition was speculated to thicken the inverse grading layer by reworking the coarse sand. Additionally, the sediment behind dunes became liquefied and showed shear deformation during the erosion. The shear deformation of liquefied sediment below the erosional surface might leave sedimentary characteristics specific to earthquake tsunamis.

Characteristics of arsenic in humic substances extracted from natural organic sediments.

The stability and dispersion of naturally occurring As have been receiving increasing attention, because As is toxic and its contamination is a widespread problem in many countries. This study investigated As fractionation and speciation in organic sediments collected from different depositional settings to elucidate the existence of stable As in humic substances. Eleven organic sediment samples were collected from marine and terrestrial alluvial regions in Hokkaido prefecture, Japan, and the chemical fraction of As and species of humic substances were identified by sequential extraction. In addition, stable As bound in organic matter was evaluated by FT-IR spectroscopy. The As fraction mainly comprised inorganic substances, especially sulfur, iron, and manganese, and terrestrial sediments (lacustrine and inland deposits) were rich in sulfides and Fe and Al (hydr)oxides. When the residual fraction was excluded, the organic fraction of As was higher in seawater sediments than in terrestrial sediments. Among humic substances, cellulose, humic acid, and hydrophilic fulvic acid were clearly associated with As accumulation, and As speciation showed that the As was of organic origin. Cellulose, an organic compound of plant origin, was abundant in As=S and As (III)=O bonds, and As accumulation was higher in sulfur-rich peat sediments, corresponding with the physiological activities of As in plants. Hydrophilic fulvic acid and humic acid in these sediments, originating from small animals and microorganisms in addition to plants, denote higher As contents and abound in As (III, V)=C and C-H, CH3 bonds even in sulfur-rich sediments. The methylated As bonds reflect the ecological transition of organisms.

A new species of the fossil beaked whale Beneziphius (Cetacea, Odontoceti, Ziphiidae) from the ocean floor off Galicia and biostratigraphic reassessment for the age of the type species

Although the fossil record of beaked whales (Cetacea, Odontoceti, Ziphiidae) is continuously improving, the geological age of new taxa is often poorly constrained. Based on a partial cranium from deep seafloor deposits off Galicia, Spain, we describe a new species of the stem beaked whale genus Beneziphius, B. cetariensis sp. nov. The latter differs from the type species B. brevirostris in the larger size, the rostrum being proportionally longer, the premaxillae being longer than the maxillae at the apex of the rostrum, the left premaxillary sac fossa being transversely concave, and the ascending process of the premaxilla reaching the vertical. Considering that the stratigraphic context of deep-sea deposits off the Iberian Peninsula is not precisely known, we provisionally propose an extended, middle Miocene to early Pliocene interval for the geological age of B. cetariensis. Nonetheless, the palynological analysis of sediment sampled from cavities in the cranium of the holotype of B. brevirostris, discovered during the second part of the nineteenth century in inland deposits of Antwerp (north of Belgium), yield an early to mid-Serravallian age (13.2-12.8 Ma, late middle Miocene). B. brevirostris is thus the oldest described species of the Messapicetus clade, a large clade of stem ziphiids in which most species are dated from the late Miocene. The description of the Galician species B. cetariensis broadens the biogeographic distribution of Beneziphius and confirms the strong ziphiid faunal affinities between the eastern coast of the North Atlantic and the southern margin of the North Sea Basin.

Using magnetic fabric to reconstruct the dynamics of tsunami deposition on the Sendai Plain, Japan — The 2011 Tohoku-oki tsunami

Abstract The magnetic fabric and grain size of sand deposits emplaced during the 2011 Tohoku-oki tsunami were studied in five trenches along a 1800 m long shore normal transect on the Sendai plain as well as in a near shore sedimentary infill of a scour depression. The magnetic susceptibility in all deposits is due to ferromagnetic minerals (mainly magnetite) making the anisotropy of magnetic susceptibility (magnetic fabric) suitable for fabric analyses. The dominant magnetic fabric is planar in all trenches and stronger in finer-grained inland deposits than in the coarser sediments. This planar fabric is related to tractive shearing of the bedload basal portion of the tsunami flow that led to the deposition of traction carpet layers. Among the various fabric parameters used for this study, the vertical evolution of the shape factor ( q ) of the magnetic ellipsoid in each trench follows the evolution of the magnetic lineation ( L ) and foliation ( F ). These parameters provide information on the hydrodynamic energy (flow speed) fluctuations during the emplacement of the tsunami deposit. For the most proximal deposits, characterized by well-sorted reworked beach sand with minor fluctuations in grain-size distribution, the magnetic fabric is sensitive to hydrodynamic energy variations during sedimentation. Reconstruction of tsunami flow orientation in the sediments, based on the orientation of the mean K max calculated for each trench, appears to be unambiguous only for the sandy infills of small topographic depressions. The variations in flow direction indicators elsewhere could be related to local variation of the flow and to micro-topographic effects. These findings are encouraging for the use of the magnetic fabric proxy in the study of paleotsunami deposits.

Nitrogen Isotope Composition of Peat Samples as a Proxy for Determining Human Colonization of Islands

The Aleutian Islands comprise a unique ecosystem, providing nesting grounds and habitat for more than ten million seabirds. No doubt their numbers were even larger prior to the introduction of foxes and rats, invasive species that have shaped the current population sizes and distributions of bird-breeding colonies. Here we present evidence that the peopling of the Aleutian Islands had the same dramatic effect on seabird populations. Analyses of nitrogen stable isotopes in Shemya Island peat deposits revealed significant 15 N enrichment of layers formed cal. 4,700–2,800 yrs BP suggesting high seabird guano input at that time. Following this period there was a sharp decline in δ15 N that coincides with the first appearance of human settlement and reflects drastic reduction in seabird abundance. The isotope signature of marine-derived nitrogen vectored by seabirds is specific only for coastal peat deposits; neither 15 N enrichment nor decline was detected in inland peat deposits.

A re-evaluation of the ‘mid-Cretaceous sauropod hiatus’ and the impact of uneven sampling of the fossil record on patterns of regional dinosaur extinction

The mid-Cretaceous of North America and Europe has long been noted for the absence of sauropod dinosaurs, leading several authors to suggest that this depauperate interval is a consequence of an end-Albian sauropod extinction. This time period has become known as the ‘mid-Cretaceous sauropod hiatus’, with the subsequent presence of titanosaurian sauropods in the latest Cretaceous of North America and Europe interpreted as the result of dispersal of taxa from South America and Africa, respectively. However, several lines of evidence indicate that this hiatus is probably a sampling artefact. New fossil and trackway discoveries have considerably shortened the hiatus, reducing it to the Turonian–early Campanian in North America, and to just two short intervals in the late Cenomanian–early Turonian and late Coniacian–Santonian of Europe. Palaeoenvironmental analyses of sauropods demonstrate an inland terrestrial preference for titanosaurs, the dominant Late Cretaceous sauropods; however, during the hiatus there was a decline in inland deposits and increase in coastal sediments in Europe and North America, which would have greatly reduced the probability of preserving titanosaurs. Neither the decline in inland deposits, nor the ‘sauropod hiatus’, occurred elsewhere in the world. Statistical comparisons also demonstrate a significant positive correlation between fluctuations in inland deposits and sauropod occurrences during the mid–Late Cretaceous in Europe and North and South America. Lastly, cladistic analyses do not place latest Cretaceous North American and European titanosaurs within South American and African clades, contradicting the predictions of the ‘austral immigrant’ hypothesis. The latter hypothesis also receives little support from biogeographical analysis of dispersal among titanosaurs. Thus, the ‘sauropod hiatus’ of North America and Europe is most plausibly interpreted as the product of a sampling bias pertaining to the rarity of inland sediments and dominance of coastal deposits preserved in these two regions during the mid-Cretaceous. The presence of titanosaurs in these areas during the latest Cretaceous can be explained by dispersal from Southern Hemisphere continents, but this is no more probable than descent from Early Cretaceous incumbent faunas or dispersal from Asia.

Reply to comment by Luigi Vigliotti on “Lost tsunami”

] About 8.3 ka ago a devastating tsunami flooded thecoasts of the Eastern Mediterranean Sea [Pareschi et al.,2006c]. That tsunami was triggered by a landslide from thecollapse of the eastern flanks of Mt. Etna volcano (Sicily,Italy), in turn inducing: (1) a scar on volcano slopes, namedValle del Bove, (2) inland deposits (Chiancone and Milounits), dated >7.6–8.3 ka cal B.P. [Calvari and Groppelli,1996; Calvari et al.,1998],and(3)offshorelandslidedeposits [Pareschi et al., 2006a]. The tsunami had a largeimpact, effecting southern Italy, western Greece and NorthAfrica (including Tunisia to Libya, Egypt, southern Turkey,Syria, Lebanon and Israel. In Israel the tsunami ravaged theNeolithic village of Atlit-Yam, caused the death of villagersand animals, filling a water well and destroying village huts[Pareschi et al., 2006c, 2007]. An early Holocene sea levelrise, dated 8,350–8,250 calendar year B.P., matches thetiming of the Mt. Etna tsunami, the consequent flooding ofcoastal areas led to the sudden loss of land favoured byearly farmers and initiated an abrupt expansion of activityacross Europe [Turney and Brown, 2007].[

Application of the Cα/Cc concept to secondary compression of sabkha soils

Sabkha soils are coastal and inland saline deposits of arid climates consisting mainly of loosely cemented sandy silt to silty clay particles. Invariably the soils contain an appreciable amount of organic material and are characterized as being highly compressible. Despite increased interest in various aspects of sabkha soil behavior, little is yet known about the nature and magnitude of secondary compression of these distinct sediments. In this paper, the secondary compression behavior of a typical sabkha formation from the southwestern coast of Saudi Arabia was investigated. Series of conventional and long-term, one-dimensional consolidation tests were conducted on natural and preloaded undisturbed samples taken from the compressible sabkha layer. The results of the laboratory investigation, substantiated by existing field data, indicated that a significant portion of sabkha settlements takes place as a secondary compression. The coefficient of secondary compression, Cα, was found to be constant, and the ratio of Cα to the compression index, Cc, is within the range reported in the published literature for various geotechnical materials. The applicability of the Cα /Cc concept to sabkha soils was further ascertained by comparing the secondary settlements estimated based on this concept with those measured directly in the field under an instrumented test embankment. Reasonable agreement was found between predictions and field observations.Key words: sabkhas, consolidation, coefficient of secondary compression, preloading, test embankment.

Sedimentological characteristics of the surficial deposits of the Jal Az-Zor area, Kuwait

The purpose of this article is to discuss the nature and characteristics of the surface geology of the Jal Az-Zor escarpment and the adjacent area, to better understand the sedimentology of desert landforms, and the main factors controlling depositional and diagenetic processes active in this environment. The oldest outcrops along the face of the escarpment are the sand and sandstone sequences of the Mutla and Jal Az-Zor Formations of the Kuwait Group (Neogene). Gravelly deposits of the upper member of the Kuwait Group, Dibdibba Formation (Pleistocene) are restricted to a few hillocks and ridges in the summit area of the escarpment. The Neogene deposits in most of the study area are overlain by a veneer of unconsolidated Holocene sediments. These were classified, according to their morphological setting and field occurrence, into: coastal deposits (intertidal mud, sabkha deposits, and sand dunes) and inland deposits (sand drifts, slope deposits, wadi fills, residual deposits and playa deposits). Wind-born quartzitic sand is the most common Holocene sediment in the study area indicating the dominance of the aeolian processes. Gypsum and carbonate present as cementing materials or in the form of gypcrete and calcrete, respectively, are characteristic sedimentological features of the pre-Holocene deposits. Gypcrete and gypsum cement are abundant in the upper section of the escarpment and decreases downward, whereas the carbonate (calcrete) shows a reverse pattern, i.e., it becomes more dominant in the lower section of the escarpment. The source of sulphate ions in the groundwater that is responsible for the development of gypcrete is believed to be the evaporites in the lower section of the Neogene sequence. The source of ions for the formation of calcrete and calcite cement is less understood due to the lack of significant primary carbonates in the near-surface deposits. It is believed that the nature and distribution of the chemically precipitated material (gypsum and carbonates) are controlled by the chemistry and hydrodynamics of the groundwater which in turn are controlled mostly by the climatic conditions, during their development, and the lithology of the host sediments. Arid and semi-arid climatic and paleoclimatic conditions are considered the most critical factors affecting the depositional and diagenetic processes impacting surficial deposits of the Jal Az-Zor area.

Recent sediments and sedimentation in the Inner Hebrides

SynopsisLittle land-derived material currently reaches the sea. Inland deposits are dominantly organic, peat succeeding lacustrine diatomite. Marine sediments result from the wave and tidal current reworking of Pleistocene glacial debris, with an admixture of Holocene skeletal carbonate. Muddy sands are accumulating in glacially overdeepened and tidally scoured hollows, reworked from moraine and outwash. Lag gravels occur on the shallows.Beach sands have a local origin, with mixtures of shelly fauna and rock fragments eroded from adjacent cliffs. Beaches are less carbonate-rich than in the Outer Hebrides, except on Coll and Tiree. They are also finer, which encourages well-developed dune systems. Calcareous dunes are locally cemented on Coll, the cementation picking out ‘fossilised’ hoof-prints.There is no transport of coastal bedload to the shelf, so that offshore sediments are more calcareous. Bivalves, barnacles, gastropods, worm tubes and sea urchins make significant contributions to the shellsand. Underwater television surveys show a diverse suite of sedimentary facies: algal gravels in shallow, sheltered tidal channels; carbonate-rich sand ribbons and sandwaves along the main tidal streams; highly burrowed muds in the deeper, lower energy areas, with many examples of penecontemporaneous nodule formation.

A New Tree-Frog (Centrolenidae) from Costa Rica

Florida. However, T. c. carolina (or bauri) type turtles seem to be represented in the Blancan deposit of Haile XV A. A single peripheral in the University of Florida collections from the Hemphillian McGehee site, Alachua County, Florida (Webb, 1964) may belong to the genus Terrapene. It is quite large, and its shape is highly suggestive of one of the posterior peripherals of T. c. putnami. A number of factors concerning this site and its contained fauna suggest that the deposit was formed in or near a stream very close to the sea. Milstead (pers. comm.) has long felt that the undoubted Pliocene deposits of Florida contain a box turtle similar or identical to T. c. putnami. If so, then contemporaneous inland deposits will probably be found to possess T. c. carolina.

The Potential Value of Several Recent American Coastal and Inland Deposits as Future Source Beds of Petroleum

Sediments obtained from several environments of deposition were assayed for their potentiality as future source beds of petroleum, by the method of dry destructive distillation. Except for deposits from an algal lake that yielded 28 gallons of oil a ton, the maximum production was about 3 gallons a ton. As is true with rocks of past geologic formations, recent sediments regarded as good potential source beds are not plentiful. The majority of modern deposits gave little or no oil on distillation and the samples from only four major regions, Lake Maracaibo, Pamlico Sound, and the limestone-forming areas of Florida and Cuba, produced more than 2 gallons a ton. In order to aid the evaluation of the potentiality of modern sediments as source beds, several deposits from past g ologic formations were assayed in the same manner in which the recent sediments were treated. The results were strikingly similar to those from modern sediments, and support the view that the richer types of recent deposits are to be considered as potential future source beds. In general, the yield of oil from modern deposits increases as the texture becomes finer. This indicates that rocks formed from clay are more likely to be source beds than those made from silt or sand. The relatively high yield from the limy oozes of Florida and Cuba indicates that limestones may be mother rocks of oil. Deposits subject to considerable tidal action do not appear to be good future source beds. A suggestion is made that the organic content of sediments deposited relatively near shore is likely to be icher than that of those laid down far from land. If this is true it supplements other evidence pointing to the importance of shore-line conditions in the formation of oil. However, locally, the distribution of organic matter in sediments is influenced by the action of waves and currents, which may cause differences in the potentiality of sediments as source beds, even though the physical characters of the deposits may seem to be similar.

Organic Material of Carbonaceous Shales

Microscopic examinations of shales associated with oil showed the presence of an ulmohumic groundmass plus other identifiable organic remains. Asphalt may be formed from the ulmohumic acid precipitates in the presence of seawater and electrolytes. Rivers and streams acted as concentrating agents for millions of tons of organic materials, which later were incorporated into marine or inland lake deposits. Heat, pressure, and catalytic agents converted the organic material to petroleum.

On the discovery of Arctic shells in high levels in Scotland

Probably no proof that a glacial climate once prevailed in our country has been more convincing than the discovery of Arctic shells at various levels throughout the United Kingdom. The subject has been very ably investigated in Scotland by such well-known geologists as James Smith of Jordanhill, Charles W. Peach of Edinburgh, T. F. Jamieson of Ellon, David Robertson and Rev. H. W. Crosskey of Glasgow, Rev. Thomas Brown of Edinburgh, and Dr James Geikie, Robert L. Jack, Benjamin N. Peach, and John Horne of the Geological Survey of Scotland. The originator of this line of research in Scotland was the late Mr James Smith of Jordanhill, who discovered in inland deposits throughout the west of Scotland a number of shells unknown to local collectors, which were submitted to M. Deshayes, the eminent French conchologist, and recognised by him as living Arctic shells. ‶This clue,″ said Mr Bennie, ‶being followed out, the great fact was established by Mr Smith in 1839 that, during the times represented by these shell-beds, the climate of Scotland was half Arctic in its character.″* Most of the discoveries in Scotland of Arctic shells have been made at low levels, such as on the sea-shore, or at a small elevation above it. I propose to show in this paper, however, that the Arctic sea which once existed in these latitudes submerged Scotland to a very considerable extent. For this purpose I shall, after glancing at similar discoveries in England and Wales and Ireland, bring under your