Tinto Area Research Articles

In situ measurement and sampling of acidic alteration products at Río Tinto in support of the scientific activity of the Ma_MISS instrument

We describe the procedures and results of a geological field analysis campaign in the Río Tinto area. This geologically/biologically well-documented site with its rock/water/biology interaction represents an ideal open-air laboratory where to collect spectral data and samples useful for testing space instruments. During the field campaign, we collected a large set of VIS-NIR (0.35–2.5 μm) measurements using the ASD FieldSpec4 portable spectrometer both on biosignature-bearing rocks and on alteration hydrated products (sulfates, clays, oxides, etc.). Furthermore, as a comparison to the data collected in the field, we report the results of the micro-Raman analyses carried out in the laboratory on the collected mineral/rock samples. This work was conducted in the framework of the Mars Multispectral Imager for Subsurface Studies (Ma_MISS) instrument that is a miniaturized visible and near-infrared (VIS-NIR) spectrometer (0.5–2.3 μm) devoted to the Martian subsurface exploration and integrated into the drilling system of the ESA Rosalind Franklin rover mission. Ma_MISS will acquire spectral data on the Martian subsurface from the excavated borehole wall. The scientific results obtained by this campaign confirm that the Río Tinto site is important for enriching the scientific community’s grasp on the Martian environment and for obtaining key information on the mineralogical and geochemical evolution of the Martian surface/subsurface. In addition, this work provides crucial preparation for the exploitation and interpretation of the scientific data that the Ma_MISS instrument will supply during the active phase of the mission. This activity is also useful for defining the priorities of the astrobiological objectives on the ground.

Fractionation of U and heavy metals into the colloidal fraction in acid mine drainage conditions in the Río Tinto area (SW Spain)

The Río Tinto mining area provides ideal conditions for studying the role of colloidal particles in concentrating. All the elements are present in higher concentrations respect to their content in common natural waters. 234U/238U activity ratio ranges between 2.286 ± 0.149 and 2.531 ± 0.151. Concentration of Fe and Al are in the order of 104–103 mg/L; Co, Zn and Cu values are three times lower than Fe and Al, but still much greater than in natural waters; U reaches values up to 40.73 μg/L. To evaluate the partitioning of these elements into the colloidal fraction, ultrafiltration (UF) experiments were made. A permeation model describing the relationship between concentration of the elements or isotopes in the permeate solution and the concentration factor (CF) was calculated. Experiments were carried out using CF from 1.5 to 25.0. The behaviour of investigated heavy metals and U can be predicted by a permeation model that provides similar permeation coefficient (Pc) for all of them (Pc = 0.95–0.97 for 50 kDa, Pc = 0.86–0.88 for 10 kDa, and Pc = 0.80–0.86 for 3 kDa). Retention for all the investigated elements occurs, resulting in up to 23% of the element associated to the 3 kDa colloidal fraction. The increase in U and heavy metals concentrations in the retentate fraction with the increasing CF is due to the retention of the colloidal fraction. The colloidal abundance of related metals increased with decreasing membrane MWCO even though the difference is small between 3 and 10 kDa fraction for some metals Characterization of colloidal material is needed to better understand the state of play in this context.

Diverse mineral assemblages of acidic alteration in the Rio Tinto area (southwest Spain): Implications for Mars

Diverse mineral assemblages of acidic alteration in the Rio Tinto area (southwest Spain): Implications for Mars

Radionuclides transfer into halophytes growing in tidal salt marshes from the Southwest of Spain

Estuaries are sinks of materials and substances which are released directly into them or transported from rivers that drain the basin. It is usual to find high organic matter loads and fine particles in the sediments. We analyzed radionuclide concentrations (210Po, 230Th, 232Th, 234U, 238U, 226Ra, 228Th, 228Ra, 40K) in sediments and three different organs (roots, stems and leaves) of three species of halophytes plants (Spartina maritima, Spartina densiflora and Sarcocornia perennis). The study was carried out in two tidal salt marshes, one polluted by U-series radionuclides and another nearby that was unpolluted and was used as a control (or reference) area. The Tinto River salt marsh shows high levels of U-series radionuclides coming from mining and industrial discharges. On the contrary, the unperturbed Piedras River salt marsh is located about 25 km from the Tinto marsh, and shows little presence of contaminants and radionuclides. The results of this work have shown that natural radionuclide concentrations (specially the U-isotopes) in the Tinto salt marsh sediments are one order of magnitude higher than those in the Piedras marsh. These radionuclide enhancements are reflected in the different organs of the plants, which have similar concentration increases as the sediments where they have grown. Finally, the transfer factor (TF) of the most polluted radionuclides (U-isotopes and 210Po) in the Tinto area are one order of magnitude higher than in the Piedras area, indicating that the fraction of each radionuclide in the sediment originating from the pollution is more available for the plants than the indigenous fraction. This means that the plants of the salt marshes are unhelpful as bioindicators or for the phytoremediation of radionuclides.

Dissolved Versus Colloidal U and Th Under Acid Mine Drainage Conditions in Río Tinto Area (Spain)

Results of ultrafiltration experiments performed in acid waters from the Río Tinto acid mine drainage system in order to evaluate the role of colloids under acid mine drainage conditions indicate that for U and Th, a constant permeation model is applicable and does produce results that are compatible with the predicted behavior of these elements under acidic conditions. Results show that around 8,7% of total U is in the colloidal fraction. Results considering the 234, 235 and 238 U isotopes show similar percentages of retention in the colloidal fraction. Th is dissolved in the acid waters of Río Tinto, which agrees with the predicted dissolved character of Th under acid and high sulfate concentration conditions

Mobility of Po and U-isotopes under acid mine drainage conditions: an experimental approach with samples from Río Tinto area (SW Spain)

Under acid mine drainage (AMD) conditions, the solubilities and mobilities of many elements are vastly different from conditions prevailing in most natural waters. Studies are underway in the Río Tinto area (Iberian Pyrite Belt), in order to understand the behavior and mobility of long-lived U-series radionuclides under AMD conditions. A set of leaching experiments utilizing typical country rocks from the Tinto River basin, waste rock pile composite materials, iron-rich riverbed sediments and gossan (weathered naturally rock) were performed towards this purpose. Initial leaching experiments using distilled water kept in contact with solid material for 300, 100, 50 and 1 h resulted in very low concentrations of U with 234U/238U activity ratios close to equilibrium and activity concentrations of 210Po < 0.03 mBq/g. Leaching experiments performed with sulfuric acid media (0.1 and 0.01 M), and contact times between the solid and solution for 24 h were conducted to quantify the amount of U-isotopes and 210Po leached, and the radioactive disequilibria generated between the radionuclides in the leachate. These experiments show that Po mobility in acidic conditions (pH around 1–2) is very low, with 210Po activity in the leachate to be 6% in average for the solid sample. By contrast, mobility of U-isotopes is higher than that of Po, around 1.2%.

Deep subsurface sulfate reduction and methanogenesis in the Iberian Pyrite Belt revealed through geochemistry and molecular biomarkers

The Iberian Pyrite Belt (IPB, southwest of Spain), the largest known massive sulfide deposit, fuels a rich chemolithotrophic microbial community in the Río Tinto area. However, the geomicrobiology of its deep subsurface is still unexplored. Herein, we report on the geochemistry and prokaryotic diversity in the subsurface (down to a depth of 166m) of the Iberian Pyritic belt using an array of geochemical and complementary molecular ecology techniques. Using an antibody microarray, we detected polymeric biomarkers (lipoteichoic acids and peptidoglycan) from Gram-positive bacteria throughout the borehole. DNA microarray hybridization confirmed the presence of members of methane oxidizers, sulfate-reducers, metal and sulfur oxidizers, and methanogenic Euryarchaeota. DNA sequences from denitrifying and hydrogenotrophic bacteria were also identified. FISH hybridization revealed live bacterial clusters associated with microniches on mineral surfaces. These results, together with measures of the geochemical parameters in the borehole, allowed us to create a preliminary scheme of the biogeochemical processes that could be operating in the deep subsurface of the Iberian Pyrite Belt, including microbial metabolisms such as sulfate reduction, methanogenesis and anaerobic methane oxidation.

Metal Uptake and Distribution in Cultured Seedlings of Nerium oleander L. (Apocynaceae) from the Río Tinto (Huelva, Spain)

Nerium oleander L. (Apocynaceae) is a micro-nano phanerophyte that grows in the riverbanks of the Río Tinto basin (Southwest Iberian Peninsula). The waters and soils of the Río Tinto area are highly acidic and have high concentrations of heavy metals. In this environment, N. oleander naturally grows in both extreme acidic (EA) and less extreme acidic (LEA) water courses, excluding, and bioindicating certain metals. In this work, we compared and evaluated the accumulation preferences and capacities, the distribution and processes of biomineralization of metals (Fe, Cu, Zn, Mn, Mg, Ca) in the first stages of growth of EA and LEA oleanders by means of inductively coupled plasma-mass spectrometry, scanning electron microscopy, and energy dispersive X-ray analyzer analysis. Seeds from both environments were grown and treated with a self-made solution simulating the most extreme red waters from the Río Tinto. LEA plants drastically reduces the metal uptake at the beginning, but later reactivates the uptake reaching concentration values in the same range as the EA plants. The results showed high Mn, Zn and Mg concentrations, accumulation of Fe and Cu in plants from both environments, differing from the metal concentrations of field-grown oleanders. Iron bioformations with traces of other metals were present inside and over epidermal cells and inside vascular cells of stems and roots. They were absent of leaves. The accumulation properties of N. oleander in its early stages of development make it a species to take in consideration in phytoremediation processes but optimized conditions are needed to ensure enough biomass production.

Metal concentration and distribution in plant tissues of Nerium oleander (Apocynaceae, Plantae) from extremely acidic and less extremely acidic water courses in the Río Tinto area (Huelva, Spain)

Nerium oleander L. is a micro–nano phanerophyte common in rivers, streams and temporary pools of water in southwestern Iberian Peninsula. In the mining area of Río Tinto, it grows in both extreme acidic and highly metal concentrated waters and in less extremely acidic water courses. In this work we study metal concentration and distribution in plant tissues of N. oleander by means of ICP-MS, SEM and EDX analysis. We observed differences between leaves and roots in the same plant, being Na, As, Fe and Pb concentrations significantly higher in the root. No differences in metal concentration and distribution between individuals of both environments were found. A deposition of Fe, Si, Al and K all over the root surface and the first cell layer of the epidermis with Pb and As in acidic water plants and Mn in less acidic water plants was observed. Ca druses and prismatic crystals were found in stems cortex and around leaves vascular bundle. Given the nutrient accumulation and the metal exclusion capacities of N. oleander, it could be of great interest in metal enriched soils phytostabilization.

SOLID2: An Antibody Array-Based Life-Detector Instrument in a Mars Drilling Simulation Experiment (MARTE)

A field prototype of an antibody array-based life-detector instrument, Signs Of LIfe Detector (SOLID2), has been tested in a Mars drilling mission simulation called MARTE (Mars Astrobiology Research and Technology Experiment). As one of the analytical instruments on the MARTE robotic drilling rig, SOLID2 performed automatic sample processing and analysis of ground core samples (0.5 g) with protein microarrays that contained 157 different antibodies. Core samples from different depths (down to 5.5 m) were analyzed, and positive reactions were obtained in antibodies raised against the Gram-negative bacterium Leptospirillum ferrooxidans, a species of the genus Acidithiobacillus (both common microorganisms in the Río Tinto area), and extracts from biofilms and other natural samples from the Río Tinto area. These positive reactions were absent when the samples were previously subjected to a high-temperature treatment, which indicates the biological origin and structural dependency of the antibody-antigen reactions. We conclude that an antibody array-based life-detector instrument like SOLID2 can detect complex biological material, and it should be considered as a potential analytical instrument for future planetary missions that search for life.

Modeling the physico‐chemistry of acid sulfate waters through Raman spectroscopy of the system FeSO4H2SO4H2O

AbstractMine waters containing extremely high concentrations of sulfuric acid and dissolved iron are found in the Rio Tinto (Spain) area. In this study, Raman spectroscopy has been used to investigate the speciation of the system iron(II)–sulfuric acid–water as an approach to study Rio Tinto's stream water. Several solutions of aqueous sulfuric acid containing iron(II) sulfate in the range 0–1.65 mol/kg were prepared, and qualitative and quantitative analyses of the ions present in the solutions were carried out using Raman spectroscopy. The intrinsic features of Raman spectroscopy allowed the identification of the species present in solution and calculation of the species concentration through band‐fitting of the Raman spectra. The activity coefficient product of the system iron(II) sulfate–sulfuric acid–water as a function of salt concentration is reported. Previous findings on the formation of iron(II) hexahydrate complexes in the mentioned system have been corroborated by means of Raman spectroscopy. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Geochemistry of acidic Rio Tinto headwaters and role of bacteria in solid phase metal partitioning

Mining operations in the Rio Tinto area, southwest Spain, have created a historical pollution problem in the river and estuary. The fate of metals along the Rio Tinto river and estuary has been previously characterized, but little is known about transport and behaviour of metals and other elements in the headwaters of the river. The headwaters are situated approximately 100 km (north east) from Huelva at the Mediterranean Sea, with three investigated sites in this area distributed over 100 m. Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) of aqueous and solid samples revealed Ca, Fe, Mg, Na, S, Si, and Al concentrations above 0.5 mM in the stream surface waters at all sites. Trace elements included K, Cu, Li, Mn, and Zn. Concentrations of particulate elements generally accounted for less than 10% of the total load. In deeper pools along the stream, brine water was found with notably higher levels of Fe, Mg, S, Si, and Al compared to the stream water. The brine had a pH of 1.9, while the surface stream waters had pH values of about 2.7. Groundwater from the seep on the bank of the stream was found to be chemically distinct from both surface stream water and the brine. Fe, S and Al were in the solid samples at 100 mmol/kg or more. K, Na, P, Si, As, Ba, Cu, Li, and Mn were characterized by intermediate concentrations, 1.0–100 mmol/kg. A progressive downstream increase in particulate elemental concentrations was observed for P, Ba, Mn, Pb, Sr, V and Zn. Scanning electron microscopy (SEM) showed a variety of bacterial-like forms among the suspended particulates. In some instances, the bacteria appeared to be closely associated with or mineralized by inorganic precipitates. Transmission electron microscopy (TEM) revealed extensively mineralized bacterial cells in the solid sediment samples. The chemical composition of the investigated stream is attributed to inputs from groundwater and brines that likely evolve in response to evaporation during prolonged periods of moisture deficit in the summer. Planktonic bacteria were prominent components of the suspended particulate fraction in the stream; however, pH sorption edges for dissolved metals on bacteria are generally above pH 4.0, and therefore, it is unlikely that bacterial cells are an important component for transport of dissolved metals in the stream. Bottom sediments contain abundant highly mineralized bacteria with coatings of poorly crystalline iron oxyhydroxides and hydroxysulfate precipitates. Such bacterial–mineral composites likely contribute to increased solid phase partitioning of dissolved metals in the Tinto river system.

The early roman imperial AES coinage II: Tracing the copper sources by analysis of lead and copper isotopes—copper coins of Augustus and Tiberius*

Lead and copper isotopes of Roman Imperial copper coins (denominations as and quadrans) were analysed by MC–ICP–MS. We concentrated on well‐dated coins minted at the official mint of Rome under the Emperors Augustus and Tiberius (between 16 bc and ad 37). The lead isotope results were compared with published lead isotope data of ore bodies from the Aegaean, Cyprus, Italy and Spain, in order to fingerprint the sources of Roman copper. During the Augustan period the main copper supply, as judged from the copper coins, is from Sardinia and south‐east Spain, with minor contributions from Tuscany. Except for Tuscany, this continued into the Tiberian period, when Cypriot copper also appears. Augustan quadrantes and late Tiberian asses came solely from the Rio Tinto area in south‐west Spain. Copper isotopes were applied here for the first time to systematic archaeometric studies. They are supplementary to lead isotopes and allow further grouping and classification of the copper coins.

Conversion of pollutants to fertilisers: ion exchange synthesis of potassium sulphate from acidic mine waters

The paper reports the results obtained by the development of ion exchange synthesis of K2SO4 from the natural acidic mine waters (AMW) of Rio Tinto area (Huelva, Spain). The process flowsheet includes several sequential stages permitting production of potassium sulphate and desalinated water along with the recovery of four metals.

4,500-YEAR-OLD MINING POLLUTION IN SOUTHWESTERN SPAIN:LONG-TERM IMPLICATIONS FOR MODERN MINING POLLUTION

The Tinto river drains the Rio Tinto mining district, which comprises the world’s largest known massive sulfide deposits; these orebodies have been mined from the third millenium BC to the present. The Tinto river is strongly acidic (pH, 1.5–2.5); during flood events, it transports a sandy material, including abundant detrital pyrite grains. A core drilled in the Holocene sediments of the Tinto estuary allows for investigation of recent and historical mining pollution. Two anomalous horizons have been recognized (0–1.3 m; 3–4 m). Both are characterized by very high metal content (100 times over the background) and by the presence of abundant clastic pyrite grains. The metal association (Pb, Ba, As, Cu, Zn, Sn, Tl, Cd, Ag, Hg, Au) is typical of that of the Rio Tinto pyritic ore. The upper horizon corresponds to the modern mining activity; the lower horizon has been dated at 2530 BC (14C AMS calibrated age). We show here that active mining occurred early (Copper Age) in the Rio Tinto area, resulting in a watershed-scale metal contamination. We also show that anthropogenic input of metals may be accumulated and immobilized during thousands of years in estuarine sediments.

Mineralogy and geochemistry of alluvium contaminated by metal mining in the Rio Tinto area, southwest Spain

The Rio Tinto in SW Spain drains Cu and pyrite mines which have been in operation since at least the Bronze Age. Extensive metal mining, especially from 1873 to 1954, has resulted in contamination of the Rio Tinto alluvium with As, Cu, Pb, Ag and Zn. X-ray diffraction (XRD), wavelength-dispersive X-ray mapping, scanning electron microscope petrography and X-ray energy-dispersive (EDX) analysis has revealed that 4 major groups of contaminant metal and As-bearing minerals, including sulphides, Fe-As oxides, Fe oxides/hydroxides/oxyhydroxides, and Fe oxyhydroxysulphates, occur in the alluvium. Sulphide minerals, including pyrite, chalcopyrite, arsenopyrite and sphalerite, occur in alluvium near the mining areas. Iron hydroxides and oxyhydroxides such as goethite and possibly ferrihydrite occur in cements in both the mining areas and alluvium downstream, and carry minor amounts of As, Cu and Zn. Iron oxyhydroxysulphates, including jarosite, plumbojarosite and possibly schwertmannite, are the most common minerals in alluvium downstream of the mining areas, and are major hosts of Cu, Pb, Zn and of As, next to the Fe-As minerals. This work, and other field observations, suggest that (1) the extreme acidity and elevated metal concentrations of the river water will probably be maintained for some time due to oxidation of pyrite and other sulphides in the alluvium and mine-waste tips, and from formation of secondary oxide and oxyhydroxysulphates; (2) soluble Fe oxyhydroxysulphates such as copiapite, which form on the alluvium, are a temporary store of contaminant metals, but are dissolved during periods of high rainfall or flooding, releasing contaminants to the aqueous system; (3) relatively insoluble Fe oxyhydroxysulphates and hydroxides such as jarosite and goethite may be the major long-term store of alluvial contaminant metals; and (4) raising river pH will probably cause precipitation of Fe oxyhydroxides and oxides/hydroxides/oxyhydroxides and thus have a positive effect on water quality, but this action may destabilise some of these contaminant metal-bearing minerals, releasing metals back to the aqueous system.

Application of the reagentless dual-temperature ion-exchange technique to a selective separation and concentration of copper versus aluminum from acidic mine waters

Acidic mine waters represent natural effluents from pyritic ore deposits and they are mainly characterized by a low pH and a high concentration of metal ions such as Fe 3+, Zn 2+, Cu 2+, Mn 2+, A1 3+, Ca 2+, Mg 2+ and Na +. The treatment of these waters is of great economic and ecological importance. The present study was targeted at the development of a reagentless and wasteless dual-temperature ion-exchange technique for concentrating copper from the natural acidic mine waters of Rio Tinto area (Huelva, Spain). The carboxylic ion exchanger (Lewatit R 250-K) and iminodiacetic resin (Lewatit TP-207) were used. Values of the resin capacity towards mine water metal ions and the equilibrium separation factors (α) for different metal ion couples have been determined at different temperatures in the range 20–80°C. Acrylic resin has been found to be selective for Al 3+ and iminodiacetic resin demonstrates high selectivity for Cu 2+. Furthermore, the sorbability of Al 3+ increases while that of Cu 2+ decreases with temperature for both resins. This effect gives the possibility for a selective thermostripping of Cu 2+ from the resins pre-equilibrated with cold mine water (at 20°C) using hot mine water at 80°C. The increase in the Cu 2+ concentration in the eluate is 30% for acrylic resin and 20% for iminodiacetic resin. The concentration of Al 3+ in the stripping solution drops to 50% in the first case and to 70% in the second.

Prehistoric Copper Mining on the Great Orme, Llandudno, Gwynedd

The discovery of evidence to suggest that copper ore was exploited at the Great Orme on a considerable scale in prehistory is of great significance in our understanding of the development of metalworking technology in the British Isles.In the past, the apparent absence from the archaeological record of a contemporaneous native mineral source for the production of copper and copper alloy artefacts during the Bronze Age has led to the assumption that raw materials, as well as metal technology, were imported from abroad. Alternatively, whilst accepting that local resources could have been exploited, it was assumed that these would have been obliterated by the mining operations of later centuries.There are now several sites on the British mainland and in Ireland which have been identified and dated as having been exploited for copper ores during the Bronze Age, of which a number, as on the Great Orme, had since seen intensive working during the 18th and 19th centuries AD. AS yet, much of the evidence has come essentially from surface excavations, but at the Great Orme surface excavation combined with underground exploration has revealed a system of workings of truly remarkable size. A series of 10 radiocarbon dates has been obtained from within the mine complex, indicating that working was carried out for over a thousand years spanning the Early to Late Bronze Age.The true extent of the surviving prehistoric workings is yet to be realized but present evidence indicates mining activity covering an area in excess of 24,000 square metres, incorporating passages totalling upwards of 5 km, penetrating to a vertical depth of 70 m.Much of the archaeological evidence contained within this report has been gained from detailed excavation carried out within surface workings, which in their own right constitute a sizeable part of the prehistoric mine. From the surface area presently exposed it is conservatively estimated that 40,000 cubic metres of material was removed during the Bronze Age. Much of the early technology represented within the surface workings reflects the technology employed in the deep workings, with the additional evidence of ancillary operations which would seem to relate solely to surface locations.Whilst the excavations reported in this paper relate to surface, or near surface, workings, they must be seen in the context of a labyrinthine complex of prehistoric workings recorded at depths of over yom (Jenkins &amp; Lewis 1991; Lewis 1994). These deep workings are the subject of parallel studies to be reported elsewhere. The known underground and surface prehistoric workings are on a scale so far unparallelled in Britain and are of international significance. Elsewhere in Europe there is evidence for the mining of copper ores at Ai Bunar in Bulgaria dated to 5840 BC (Cernych 1978) and at Rudna Glava in former Yugoslavia dated to 4715 BC (Jovanovic 1979). Evidence for subsequent copper mining has been dated to 3785 BC in southern Spain (Rio Tinto area: Rothenburg &amp; Blanco Freijeiro 1980) and to 3330 BC in Austria (Mitterberg; Pittioni 1951), marking an apparent development and extension westwards and northwards of copper technology. More recently, the dating of two sites in the south of France to around 3330 BC, at Cabrieres (Ambert et al. 1990) and Bouche Payrol, near Brusque (Barge 1985), has confirmed another area of Bronze Age working.

Separation of copper and zinc from waste acidic mine effluents of Rio Tinto area

A study of removal of Copper and Zinc from acidic mine effluents by means of chelating ion exchange resins has been carried out. The effluents having pH ranging from 1.7 to 1.9, contain mainly iron, copper and zinc and some other elements at much lower concentrations. The study includes chemical characterisation of effluents samples, the assessment of chelating resins and their selectivity for the separation of copper and zinc. Chelating resins containing either carboxylic, phosphoric or/and amine groups have been employed. The results obtained are correlated to the specific metal-complexing group attached to the polymer matrix. Resins containing carboxylate groups were found to provide most selective copper/zinc separations. A conceptual flowsheet of the separation process based on the data obtained for treating the effluents with different resins is presented.

A subglacial drainage system by the Tinto Hills, Lanarkshire

A system of meltwater channels and related eskers and other deposits situated by the Tinto Hills in south Lanarkshire is described and interpreted as largely of subglacial origin. The Thankerton ‘ kame ’ is reinterpreted as an esker system and Charlesworth9s Lake Clyde is discussed. Evidence is given for the existence of stagnant ice in the Tinto area during the formation of the glacial drainage features and the application of the stagnation hypothesis to a large part of the Southern Uplands is briefly discussed.