Pleistocene landscapes in central Iberia inferred from pollen analysis of hyena coprolites

New pollen data from hyena coprolites from central Spain are presented. The fossil faecal material has been recovered from two karstic systems in different localities, Villacastín and Los Torrejones, which are both around 1000 m a.s.l. The combined findings of bone remains and coprolites in both locations suggest the following chronology: late Middle Pleistocene for Villacastín and early Upper Pleistocene for Los Torrejones. The environments inferred from pollen are broadly in keeping with evidence from associated vertebrate fossil remains, and include a shifting mosaic of open and wooded habitats with abundant pine and juniper species, steppe‐grassland areas with composites and chenopods, and enclaves with mixed oak forests. However, Los Torrejones appears to have been less forested than Villacastín. The abundance of oaks in Villacastín may imply the presence of refugia within an interconnected network of several enclaves during the glacial stages in the Upper Pleistocene. A possible explanation for the patchiness of the landscape may be in the role of herbivores, although the long distances and variety of habitats that hyenas had to roam through could be another explanation for the heterogeneous pollen contents in their dung. Copyright © 2006 John Wiley & Sons, Ltd.     

Pollen analysis of some mid-Pleistocene interglacial lagoonal sediments from southern Delaware

Results of pollen analysis on lagoonal sediments from southern Delaware, dated at 500,000–1,000,000 yr B.P. by amino acid racemization, are presented. Three pollen zones are identified in sediments that were deposited during the final stage of an interglacial cycle. A closed forest of mixed conifer-deciduous trees dominated by Tsuga, Pinus, Fagus, Liquidambar, and Quercus is recorded in the basal zone (Zone I). The inferred climate at this time was temperate and moist. A probable lowering of sea level during the deposition of Zone II exposed large areas in the surrounding estuaries and tidal flats which were colonized by marsh and bog plant taxa. Zone III is characterized by Pinus, Quercus, and Picea pollen. A scrub oak-pine association may have been favored on the coarse sandy soils of the Delmarva Peninsula at this time because of a drop in the local water table. The inferred climate during this interval was colder and probably drier than in Zone I.     

Mineral paragenesis of the Kalahari managanese field, South Africa

The mineralogy of the managanese ores of the giant Paleoproterozoic Kalahari manganese deposit of the Transvaal Supergroup has been subject of many studies and up to now 135 different ore and gangue minerals have been described, of which eight represent new mineral species. Through correlation of different mineral assemblages with specific geological events and by determining relative ages of minerals in outcrop, hand specimen and under the microscope an attempt is made in this publication to construct a paragenetic sequence for this complex mineral assemblage. Sedimentation and early diagenesis of the Hotazel Formation, composed of interbedded iron formation and braunite lutite, was followed by low-grade metamorphism and associated stratabound metasomatism. Braunite lutite of sedimentary origin, comprising 97% of the total ore reserve, is composed of braunite, hematite and kutnahorite, and abundant early diagenetic kutnahorite and manganoan calcite forming laminae and ovoids. Fluid flow during late diagenesis or lower greenschist facies metamorphism led to stratabound metasomatic oxidation of Mn-bearing carbonates to hausmannite and Mn-poor calcite. Three structurally controlled hydrothermal alteration events succeed metamorphism. These events are referred to as Wessels, Mamatwan and Smartt events. The Wessels alteration event is the oldest of the three events and it is of great economic importance because virtually all of the high-grade ore (> 42% Mn), 3% of the total ore reserve, formed during this event through alteration of carbonate-rich low-grade Mamatwan-type ore (braunite lutite) to high-grade, carbonate-poor Wessels-type manganese ore. This Wessels hydrothermal alteration event took place in the northwestern part of the Kalahari deposit, associated with a system of major north-south- and minor east-west-striking normal faults. The Mamatwan alteration event is observed throughout the Kalahari manganese deposit but alteration is very localized. Reduction halos and discolouration of braunite lutite around fracture or joint-hosted sulphide-carbonate mineralization are typical of the Mamatwan alteration event. In contrast, the Smartt alteration event is characterized by oxidation of braunite lutite and the formation of todorokite and manganomelane. Syn- and Post-Kalahari supergene alteration has taken place below the suboutcrop of the Hotazel Formation against the calcretized sediments of the Cenozoic Kalahari Formation. Cryptomelane and pyrolusite are the predominant products of surficial weathering.     

Late Quaternary fluvial activity in the dry valleys (mekgacha) of the Middle and Southern Kalahari,southern Africa

Kalahari dry ‘fossil’ valleys (mekgacha) have been little used in palaeoenvironmental reconstruction, partly because the origins and functions of the valleys are a subject of debate, and partly because they contain few datable sediments. In the Middle Kalahari the valleys are endoreic, and, following a decline in ground-water tables owing to human interference over the past 150 years, rarely contain water. Evidence from three sites suggests that the valleys contained standing water between 15000 and 12000 yr BP, and that the main Okwa-Mmone system flowed into palaeolake Makgadikgadi at 920 m a.s.l. during this period. The Southern Kalahari contains the exoreic Molopo network which is hydrologically more active, being prone to surface flows in response to extreme rainfall events. The spring—fed Kuruman valley has two terraces, the lower composed of a series of flood deposits of late Holocene age. The flood of February 1988 provides a useful analogue for the conditions under which these deposits were formed, and of the temporal regime of the Kuruman River. Comparison with adjacent sites suggests that evidence put forward to indicate cycles of climatic amelioration in the last 4000 yr may, in part, represents the effect of extreme precipitation events. Historical floods show a strong correlation to Southern Oscillation high-phase (cold event) episodes, suggesting possibilities for extension of the Southern Oscillation record through palaeoflood studies.     

Late Cenozoic paleoclimates of the Gaap Escarpment, Kalahari margin, South Africa

The Gaap Escarpment is a dolomite cuesta demarcating the southeast margin of the Kalahari. Since Miocene-Pliocene times, thick masses of lime tufa have repeatedly accumulated at several points along this escarpment, and four regional sequences are described. These allow discrimination of six major depositional complexes, commonly characterized by basal cryoclastic breccias or coarse conglomerates that reflect frost shattering and torrential runoff, followed by sheets and lobes of tufa generated in an environment substantially wetter than today. A chronostratigraphy for the last 30,000 yr is provided by ¹⁴C dating, with direct or indirect correlations to the Vaal River sequence. The regional stratigraphy as well as faunal dating indicate an early Pleistocene age for Australopithecus africanus at Taung. Repeated episodes of protracted cold or wetter climate or both begin in terminal Miocene times, and the last Pleistocene cold-moist interval began after 35,000 yr B.P. and ended 14,000 yr B.P. Early and late Holocene times were mainly wetter, whereas the middle Holocene was drier than today. The paleoclimatic sequence differs from that of the southern and southwestern Cape or that of East Africa, but close parallels are evident throughout the lower Vaal Basin and the southern Kalahari. The tufa cycles provide a unique, 5,000,000-yr record of climatic variation in the Kalahari.summer-rainfall belt that can be related to complex anomalies of the general atmospheric circulation.     

Microflora from sauropod coprolites and associated sediments of Late Cretaceous (Maastrichtian) Lameta Formation of Nand-Dongargaon basin,Maharashtra

Micofloral study of Lameta sediments and associated sauropod coprolites in the Nand-Dongargaon basin in Maharashtra was conducted to understand the diet and habitat of sauropods. The study revealed the presence of pollen, spores, algal and fungal remains, well-preserved cuticles of Poaceae, and testate amoebae. Vegetation during Lameta included tall arboreal taxa, such as conifers (Podocarpus and Araucaria), Cycads (Cycas), Euphorian and Barringtonia and herbs and shrubs, such as Cheirolepidiaceae (Classopollis), Arecaceae (Palmaepollenites), Poaceae (Graminidites), Asteraceae (Compositoipollenites), Caryophyllaceae (Cretacaeiporites and Periporopollenites), and Acanthaceae (Multiareolites). Data suggest that the sauropods ate soft tissues of angiosperms and gymnosperms. The intake of testate amoeba, algal remains, sponge spicules, and diatoms might be through water intake.     

The formation and sedimentary infilling of the Cave of Hearths and Historic Cave complex,Makapansgat, South Africa

The archaeology of caves is best served by including a study of natural effects prior to and during anthropogenic input. This is especially true for the Cave of Hearths because not only has erosion determined the area of occupation, but also subsequent undermining has caused collapse of some of the rearward parts of the site during Early Stone Age (Acheulian) and later times; and this had a major impact on excavation. The key to understanding the nature of the collapsed layers was the rediscovery of a lower part of the cavern below the whole site. This lower cavern is no longer accessible, but the evidence for it was revealed in a swallow hole by R.J. Mason, and in archived material at the Department of Archaeology, University of Witwatersrand. The creation and dissolution of dolomite fragments in the upper layers has resulted in the formation of thick, carbonate‐cemented breccia that has preserved underlying layers and prevented further collapse. We agree with Mason that further archaeological and hominid finds await excavation under the proximate Historical Cave west entrance. This area has the potential for archaeological and palaeoanthropological material that predates the layers in the Cave of Hearths. © 2004 Wiley Periodicals, Inc.     

Phase relations of talc and tremolite in metamorphic calcite-dolomite sediments in the southern portion of the Damara Belt (South West Africa)

The occurrence of talc and tremolite in a temperature gradient was investigated in siliceous calcite-dolomite sediments exposed along a strip in the southeastern part of the Damara Orogen. Five bivariant reactions may lead to the formation of talc and tremolite:

1. 3 dolomite+4 quartz+1 H₂O ? 1 talc+3 calcite+3 CO₂
2. 5 talc+6 calcite+4 quartz ? 1 tremolite+6 CO₂+2 H₂O
3. 2 talc+3 calcite ? 1 tremolite+1 dolomite+1 CO₂+1 H₂O
4. 5 dolomite+8 quartz+1 H₂O ? 1 tremolite+3 calcite+7 CO₂
5. 2 dolomite+1 talc+4 quartz ? 1 tremolite+4 CO₂.

The common paragenesis of four mineral assemblages tc+cc+dol+qtz¹ and tre+tc+ cc+qtz with increasing temperature over an extended area show that the reactions must have taken place along the equilibrium curve or when fluid pressure is not constant along the equilibrium plane of reactions (1) or (2). The described occurrence of the five mineral assemblage tre+tc+cc+dol+qtz can be stable only on the isobaric intersection point, or when P _f is variable on the univariant intersection curve of the equilibrium planes of all five reactions. The genetic relations of the described parageneses are illustrated with the help of a phase diagram. Minimum P-T conditions which prevailed during metamorphism in this part of the Damara Orogen have been estimated to be about 590° C and 5 kb.     

The southern cape conductive belt (South Africa): Its composition, origin and tectonic significance

Magnetometer array studies have led to the discovery and mapping of the Southern Cape Conductive Belt (SCCB) crossing the southern tip of Africa from west to southeast coasts. The SCCB lies just south of the Namaqua-Natal Belt of cratonic rocks remobilized about 1000 m.y. B.P. It is shown that it coincides with a zone of weakness which has been exploited by three major geosynclinal accumulations over some 600 m.y. Relationships between the SCCB and the basement geochronology, geology and tectonics are considered in detail. These relationships support the view that the conductive belt was formed by an accumulation of marine sediments and oceanic lithosphere at the top of a Proterozoic subduction which stopped about 1000 to 800 m.y. B.P. Associated with this subduction we propose a Proterozoic range of Andean mountains, whose roots are now exposed in the Namaqua-Natal Belt. Later subduction further south, near the present south coast, is proposed to account for the intrusion, between the south coast and the SCCB, of the Cape Granites in the time interval 600-500 m.y. B.P. There is some evidence for a third, yet more distant, subduction episode off Permian Gondwanaland. After outlining this tectonic history, the paper turns to a closer examination of the hypothesis that the Southern Cape Conductive Belt consists of partly serpentinized basalt accumulated at the top of a Proterozoic subduction. A large static magnetic anomaly, which correlates with the SCCB over most of its length, is well fitted by a model which strongly supports this hypothesis. Bouguer gravity anomalies along western and central profiles likewise support the hypothesis. A discussion follows of the process of formation of the proposed block of serpentinized marine rocks, beginning with serpentinization of the crust near oceanic ridges by reaction of warm, porous, newly-extruded basalt with seawater convecting through it. The serpentinized basalt is stable at crustal temperatures and pressures and so is transported in the seafloor until it reaches a subduction, where it accumulates because of its low density. Examples of such accumulations are cited. Finally, it is shown that any iron in the olivine and pyroxene in the original basalt precipitates, when these silicates are hydrated to serpentine, as magnetite which is the dominant mineral conferring high electrical conductivity and high magnetic susceptibility on serpentinites. In particular the Beattie static magnetic anomaly requires, in our model calculation, a very high susceptibility readily attainable in basalt at 15–20% serpentinization. The authors know of no other rock able to provide this high susceptibility. A similar percentage of serpentinization provides the density required to model the gravity anomalies.     

Submarine debris flow deposits from the Upper Carboniferous Dwyka Tillite Formation in the Kalahari Basin, South Africa

ABSTRACT Four types of sediment gravity flow deposits occur interbedded with rhythmite shale, siltsone, mudstone and minor diamictite in a 230-m thick Carboniferous glacial sequence. Shear and plug zones are present in the cohesive debris flow deposits which have a diamictic texture. The high-density turbidity flow deposits which consist of coarse to medium-grained clastics, are characterized by both normal and reverse grading. The medium to fine-grained low-density turbidity flow deposits show normal grading and consist of Bouma units A, B, D and E. Deposition occurred by gravity flow, suspension settling and minor basal melt-out during ice retreat along the southern margin of the Kalahari Basin. Immediately basinwards of the ice grounding line a proximal diamictite facies consisting predominantly of cohesive and high-density turbidity flow deposits, and minor melt-out tills formed. A distal sedimentary facies of graded sandstone and siltstone units deposited by low-density turbidity flows and suspension settling of muds with ice-rafted debris is located basinwards.     

Holocene cool‐water carbonate and terrigenous sediments from southern Spencer Gulf,South Australia

Holocene sediments from southern Spencer Gulf are cool‐water carbonate‐rich gravels and sands, dominated by molluscs and Bryozoa. Five sedimentary fades are recognized: (i) molluscan gravel; (ii) branching coralline‐algal gravel, associated with shallow partially protected environments; (iii) molluscan‐biyozoan sand; (iv) mixed bioclastic sand, representative of the deeper central region of the lower gulf; and (v) bryozoan gravel, an isolated fades developed in a semi‐protected micro‐environment. The southern gulf is characterized by complex oceanographic conditions together with variations in water depth and substrate. The sediments share the characteristics of both the southern shelf and upper Spencer Gulf. Grain‐size distribution and sedimentary facies are controlled by a combination of all the above processes. Past sea level fluctuations are recognized from sea floor strand‐line deposits. The relic component of the palimpsest sediments has eroded from the Pleistocene aeolianite dunes. The sediments, therefore, reflect both the modern marine and past environments.     

Speleology and magnetobiostratigraphic chronology of the Buffalo Cave fossil site, Makapansgat, South Africa

Speleological, stratigraphic, paleomagnetic and faunal data is presented for the Buffalo Cave fossil site in the Limpopo Province of South Africa. Speleothems and clastic deposits were sampled for paleomagnetic and mineral magnetic analysis from the northern part of the site, where stratigraphic relationships could be more easily defined and a magnetostratigraphy could therefore be developed for the site. This is also where excavations recovered the fossil material described. A comparison of the east and South African first and last appearance data with the Buffalo Cave fauna was then used to constrain the magnetostratigraphy to produce a more secure age for the site. The magnetostratigraphy showed a change from normal to reversed polarity in the basal speleothems followed by a short normal polarity period in the base of the clastic deposits and a slow change to reversed directions for the remainder of the sequence. The biochronology suggested an optimal age range of between 1.0 Ma and 600,000 yr based on faunal correlation with eastern and southern Africa. A comparison of the magnetobiostratigraphy with the GPTS suggests that the sequence covers the time period from the Olduvai event between 1.95 and 1.78 Ma, through the Jaramillo event at 1.07 Ma to 990,000 yr, until the Bruhnes-Matuyama boundary at 780,000 yr. The faunal-bearing clastic deposits are thus dated between 1.07 Ma and 780,000 yr with the main faunal remains occurring in sediments dated to just after the end of the Jaramillo Event at 990,000 yr.     

Oxygen isotopic ratios in fine quartz silt from sediments and soils of southern Africa

Fine quartz silt (1–10μm dia, important in aerosol dust) isolated from a large number of soils, as well as Phanerozoic shales, sandstones and recent sands of the southern African stratigraphie column (Carboniferous, Permian and Triassic) exhibits a mean δ¹⁸O of 12.2 ± 2.1%0. These values are similar to those reported for South Pacific pelagic sediments and adjacent land areas of similar latitude but are lower than those reported for this size fraction of 30 Mesozoic and Paleozoic shales (20.7 ± 1.8%.) and soils from mid-continental U.S.A., for aerosol quartz in the North Pacific pelagic sediments, and for eolian caps in high-elevation soils of Hawaii. The lower oxygen isotopic ratios in fine quartz silt of southern Africa reinforces the earlier indication that Southern Hemisphere detritai sedimentary reservoirs contain a higher proportion of igneous and metamorphic quartz (lower δ¹⁸O) and less lowtemperature authigenic quartz (higherδ¹⁸O) than Northern Hemisphere detritai sediments. The difference reflects climates, as continents drifted in latitude.     

Pollen stratigraphy of the Late Pleistocene sediments at Mommark, Als, South Denmark

Past environmental changes in the Baltic area are discussed on the basis of pollen and spores recovered from marine sediments in a series of cliff sections at Mommark, in southern Denmark. The sediment succession represents Jessen & Milthers' (1928) Eemian pollen zones c-h, or Andersen's (1961 1975) zones E1/2-E7, as well as the earliest Weichselian pollen zone i, or EW-1, the Herning Stadial. A correlation with annually laminated German sequences (e.g. Bispingen) indicates that the sequence spans approximately 11 000 years. Marine deposition began c. 300 years after the beginning of the Eemian Interglacial Stage and continued to shortly before the end of pollen zone E7, at c. 10 600 years after the beginning of the Eemian. Sedimentation rates varied through the time period represented by the sequence, with initial deposition relatively rapid at c. 0.35 cm yr^-1 for the first c. 300 years. Rates then decreased to 0.029 cm yr^-1 for the next 2700 years and remained low, though varying, throughout the rest of the sequence. Overall, the rates indicate that sediment supply was highly restricted throughout the interglacial, possibly reflecting the dense forest vegetation that colonized the hinterland.     

Last Glacial Maximum dune activity in the Kalahari Desert of southern Africa: observations and simulations

It has long been understood that as ephemeral landscape features sand dunes are highly sensitive to environmental change, and thus their distribution and the timing of their development may provide clues to past climate dynamics. The relationship between climate and dune activity, however, is neither simple nor straightforward, with a range of controls affecting the balance between erodibility (the availability of sediment for deflation) and erosivity (the potential for sediment transport). To explore such complex systems over large spatial and temporal scales, a number of dune activity indices (DAI) have been created that incorporate wind speed and moisture balances to calculate the potential for, and degree of dune mobilisation. Using modern weather station data, these indices have generally been shown to provide reasonable indications of dune activity potential. Until recently, however, the detailed quantitative data required to inform these equations has not been available for past climate scenarios, and attempts to determine the relative importance of the various controls of dune activity have relied on rough estimations of climatic parameters. This paper combines data from monthly general circulation model (GCM) outputs from the coupled Ocean-Atmosphere GCMs for 21 ka with the most detailed DAI equation presently available to calculate the potential for dune reactivation in southern Africa during the Last Glacial Maximum (LGM, 18–24 ka). Based on these data and calculations it is indicated that there was significantly less potential for dune activity across southern Africa at 21 ka. When compared to the aeolian sediment records from the region, this study poses serious and fundamental questions about: 1) the reliability of the model outputs, 2) the degree to which DAIs are able to account for the complexity and dynamics of aeolian systems, and/or 3) the interpretation of dune records as palaeoclimatic proxies at millennial time scales.     

Radiocarbon dating from 40 to 60 ka BP at Border Cave,South Africa

We present 21 radiocarbon dates on 19 charcoal samples from the sedimentary sequence preserved in Border Cave, South Africa. The background radiocarbon activity for charcoal from the cave was determined to be 0.050±0.018 percent modern carbon, from the analysis of a radiocarbon-dead sample from unit 5WA. Radiocarbon ages for individual samples ranged from 25.2 to >58.2 ka BP.The error-weighted mean ages for successively older strata are 38.5+0.85/−0.95 ka BP for unit 1WA, 50.2+1.1/−1.0 ka BP for units 2BS.LR.A and 2BS.LR.B, 56.5+2.7/−2.0 ka BP for unit 2BS.LR.C and 59.2+3.4/−2.4 ka BP for unit 2WA. This radiocarbon chronology is consistent with independent chronologies derived from electron spin resonance and amino acid racemization dating. The results therefore provide further evidence that radiocarbon dating of charcoal by the ABOX-SC technique can yield reliable radiocarbon ages beyond 40 ka BP. They also imply that Border Cave 5, a modern human mandible, predates >58.2 ka BP and that the Middle Stone Age (Mode 3)—Later Stone Age (Mode 5) transition of Border Cave was largely effected between ∼56.5 and ∼41.6 ka ago.     

Timing of supergene enrichment of low-grade sedimentary manganese ores in the Kalahari Manganese Field,South Africa

Low-grade carbonate-rich manganese ore of sedimentary origin in the giant Kalahari Manganese Field, South Africa, is upgraded to high-grade todorokite–manganomelane manganese ore by supergene alteration below the unconformity at the base of the Cenozoic Kalahari Formation. Incremental laser-heating ⁴⁰Ar/³⁹Ar dating of samples from the supergene altered manganese ore suggest that chemical weathering processes below the Kalahari unconformity peaked at around 27.8 Ma, 10.1 Ma and 5.2 Ma ago. Older ages are dominant in the upper part of the weathering profile, while younger ages are characteristic of the deeper part of the profile. Younger ages partially overprint older ages in the upper part of the weathering profile and demonstrate the downward progression of the weathering front by as little as 10 cm per million years. The oldest age obtained in the weathering profile, namely 42 Ma, is considered a minimum estimate for the onset of the post African I cycle of weathering and erosion that followed the break up of Gondwanaland and formation of the Cretaceous to early Cenozoic African land surface. The youngest ages, recorded at around 5 Ma, in turn, correspond well to the Pliocene transition from humid to arid climatic conditions in Southern Africa.     

Deglaciation sequences in the Permo-Carboniferous Karoo and Kalahari basins of southern Africa: a tool in the analysis of cyclic glaciomarine basin fills

The Late Westphalian to Artinskian glaciomarine deposits of the Karoo and Kalahari basins of southern Africa consist of massive and stratified diamictite, mudrock with ice-rafted material, sandstone, silty rhythmite, shale and subordinate conglomerate forming a cyclic succession recognizable across both basins. A complete cycle comprises a resistant basal unit of apparently massive diamictite overlain by softer, bedded stratified diamictite, sandstone and mudrock with a total thickness of as much as 350 m. Four major cycles are observed each separated by bounding surfaces. Lateral facies changes are present in some cycles. The massive diamictites formed as aprons and fans in front of the ice-grounding line, whereas the stratified diamictites represent more distal debris-flow fans. The sandstones originated in different environments as turbidite sands, small subaqueous outwash channel sands and delta front sands. The rhythmites and mudrock represent blanket deposits derived from turbid meltwater plumes. Cycles represent deglaciation sequences which formed during ice retreat phases caused by eustatic changes in the Karoo and Kalahari basins. Evidence for shorter-term fluctuation of the ice margin is present within the major advance-retreat cycles. Hardly any sediment was deposited during lowstand ice sheet expansion, whereas a deglaciation sequence was laid down during a sea-level rise and ice margin retreat with the volume of meltwater and sediment input depending on temporary stillstands of the ice margin during the retreat phase. The duration of the cycles is between 9 and 11 Ma suggesting major global tectono-eustatic events. Smaller cycles probably linked to orbital forcing were superimposed on the longer-term events. A sequence stratigraphic approach using the stacking of deglaciation sequences with the ice margin advance phases forming bounding surfaces, can be a tool in the framework analysis of ancient glaciomarine basin fills.     

Caliche profile formation, Saldanha Bay (South Africa)

A sequence of gradational lithification events can be observed in caliche profiles, in the Saldanha Bay area (South Africa), from friable lightly cemented aeolian calcarenites or littoral shelly deposits through an intermediate semi-indurated zone to an upper strongly indurated zone (calcrete). Lightly cemented sediment fabrics exhibit bridge and meniscus cements, micritic druses and vadose compaction phenomena. The middle semi-indurated zones exhibit coated grains in which irregular borings and/or tubules with tangential acicular fibres contribute to coated grains. Random networks of acicular fibres also occur in void spaces. In fully indurated upper layers of the caliche profiles, fabrics of micriteand microspar (in voids) occur in complex brecciated macro-fabrics. The features represent changes in a sequence from the friable primary sediments to the calcretes. Fresh-water vadose flushing leaches grains and causes formation of meniscus and bridge cements and uneven druses. In the middle zone, inorganic processes are aided by the action of micro-organisms; fungi, bacteria or algae which produce tubules and irregular borings; the overall effect of which is to break down original detrital carbonate particles and enclose them in a crypto-crystalline micrite. The acicular fibres probably result from evaporation of supersaturated solution. Mechanical processes cause fracturing, which repeated many times gives complicated brecciated fabrics within the upper indurated zone.