October Revolution Island Research Articles

Provenance and Stratigraphy of the Upper Carboniferous—Lower Permian Strata of October Revolution Island (Severnaya Zemlya Archipelago): Implications for Geological History of the Russian High Arctic

Small depressions across the north-eastern part of October Revolution Island (Severnaya Zemlya archipelago, Kara terrane) are filled with continental terrigenous rocks, dated as Upper Carboniferous–Lower Permian in age based on palynological data. These rocks overlie Ordovician volcaniclastic rocks above a prominent angular unconformity. U-Pb dating of detrital zircons from the Late Carboniferous–Lower Permian rocks reveals that most grains are Ordovician in age, ranging between 475–455 Ma. A subordinate population of Silurian detrital zircons is also present, contributing up to 15% of the dated population, while Precambrian grains mainly yield Neo-Mesoproterozoic ages and do not form prominent peaks. The combined U-Pb and (U-Th)/He ages indicate that most zircon (U-Th)/He ages were reset and average at ca. 317 Ma, suggesting ~6–7 km of Late Carboniferous uplift within the provenance area. This provenance area, mainly comprising Ordovician magmatic and volcanic rocks, was located close to the study area based on the coarse-grained nature of Late Carboniferous–Lower Permian rocks of north-eastern October Revolution Island. Therefore, we propose that Late Paleozoic tectonism significantly affected both the southern margin of the Kara terrane, as previously supposed, and also its north-eastern part. We propose that the Late Paleozoic Uralian suture zone continued to the north-eastern October Revolution Island and was responsible for the significant tectonic uplift of the studied region. This suture zone is now hidden beneath the younger Arctic basins.

The first evidence of Late Ordovician magmatism of the October Revolution Island (Severnaya Zemlya archipelago, Russian High Arctic): geochronology, geochemistry and geodynamic settings

The first evidence of Late Ordovician magmatism of the October Revolution Island (Severnaya Zemlya archipelago, Russian High Arctic): geochronology, geochemistry and geodynamic settings

Two bryozoan assemblages from the Ordovician of the Russian Arctic

Two assemblages from the Ordovician rocks of the Arctic region contain exclusively trepostome bryozoans. The first assemblage from the Yunoyaga Formation (Middle Ordovician) of Maly Oleniy Island, Novaya Zemlya, contains Monticulipora mammulata d’Orbigny, 1850 and Nicholsonella vaupeliformis Modzalevskaya, 1955. Both species possess thick-branched ramose colonies characteristic for rather high energy environments. The second assemblage comes from two localities of the Stroinaya Formation (Upper Ordovician) of the October Revolution Island containing the single species Amplexopora angusta Astrova, 1965. The monospecific bryozoan fauna of branched, rarely encrusting growth forms and sedimentological characteristics of embedding rocks (floatstone) suggest low energy conditions in deeper environments, apparently accompanied by high salinity conditions.

Development of the exoskeleton in osteostracans (Agnatha, vertebrata): New evidence of growth

In the past decade, considerable progress has been made towards a better understanding of the development of the dermal skeleton in osteostracans. Based on the study of the fine shield structure in Thyestes verrucosus Eichwald, 1854 from the Silurian of Saaremaa Island (Estonia), a model for the formation of its exoskeleton was proposed (Afanassieva, 2002, 2004b). New information on well-preserved juvenile Superciliaspis gabrielsei (Dineley et Loeffler, 1976) from the Lower Devonian of Canada, North West Territories, allowed the determination of ontogenetic patterns of the dermal skeleton in the tessellated taxon (Hawthorn et al., 2008). A comparison of the data on shield development in consolidated Thyestes and tessellated Superciliaspis and also additional study of the material of Thyestes verrucosus corroborated the previous conclusions and displayed new features of the formation of exoskeleton in this species. A different formation pattern of the exoskeleton was established in Paraungulaspis arctoa (Afanassieva et Karatajūtė-Talimaa, 1998) from the Lower Devonian of October Revolution Island of the Severnaya Zemlya Archipelago, Russia (Afanassieva, 2011; Afanassieva and Karatajūtė-Talimaa, 2013). A comparison of the exoskeleton structure and growth of the hard covering in Thyestes verrucosus and Paraungulaspis arctoa corroborated the conclusion that these species belong to different phyletic lineages of osteostracans.

New data on osteostracans (Agnatha) from the Lower Devonian of the Severnaya Zemlya Archipelago

The osteostracans Reticulaspis menneri gen. et sp. nov. and Nucleaspis unica gen. et sp. nov. from the Lower Devonian Severnaya Zemlya Formation of October Revolution Island of the Severnaya Zemlya Archipelago are described. The perfect preservation of the exoskeleton structure of Reticulaspis menneri allows the design and growth mode of the exoskeleton, with a continuous reticular dental surface of the cephalothoracic shield to be characterized. Nucleaspis unica is represented by a juvenile stage, which is extremely scarce in this vertebrate group. The preoccupied generic name Ungulaspis Afanassieva et Karatajūtė-Talimaa, 1998 is replaced by Paraungulaspis.

TanDEM-X First DEM Acquisition: A Crossing Orbit Experiment

This letter describes the first interferometric acquisitions and results obtained by the TerraSAR-X add-on for Digital Elevation Measurements mission. Due to the large along-track separation between the two satellites during the approaching maneuver and the Earth's rotation, useful interferometric acquisitions were only possible at high latitudes. This resulted in a crossing angle between the ground tracks whose impact was corrected by acquiring the two synthetic-aperture radar images with an opposite squint. The still very large 2-km cross-track baseline resulted in a 3.8-m interferometric height of ambiguity, producing extremely detailed images of the topography of the target area. Results acquired over the October Revolution Island, Russia, are shown and discussed.

Cruziana semiplicata from the Furongian (Late Cambrian) of Severnaya Zemlya Archipelago, Arctic Russia, with a review of the spatial and temporal distribution of this ichnospecies

The Furongian (Late Cambrian) Kurchavinskaya Formation of October Revolution Island, Severnaya Zemlya Archipelago, Arctic Russia, contains two distinctive morphotypes of the trace fossil Cruziana, both of which we assign to Cruziana semiplicata. A wider form shows characteristics typical of this ichnospecies with inner and outer lobes and marginal ridges. A narrow form has only an inner lobe with siculate, often interfering scratch-marks, and rare, narrow marginal ridges. This narrow form, which shows characters in common with Cruziana tortworthi, probably represents burrowing in a strongly head-down orientation. The record from October Revolution Island provides additional evidence that the palaeogeographical distribution of Cruziana semiplicata is not restricted to Gondwana, but also extend to parts of Baltica and North Kara. Cruziana semiplicata is known from the Furongian and Tremadocian of Gondwana, whereas on Baltica it is known only from the Furongian. Copyright © 2010 John Wiley & Sons, Ltd.

Recent literature on lichens—212

Adamo, P., R. Bargagli, S. Giordano, P. Modenesi, F. Monaci, E. Pittao, V. Spagnuolo & M. Tretiach. 2007. Natural and pre-treatments induced variability in the chemical composition and morphology of lichens and mosses selected for active monitoring of airborne elements. Environmental Pollution 52(1): 11–19. [Study on Hypnum cupressiforme and Pseudevernia furfuracea from Italy. Specimens exposed in nylon bags to various treatments. ‘‘Pre-treatments remarkably changed the chemical composition of selected materials but not their surface morphology. Anyhow, water-washed and oven-dried moss shoots resulted the most suitable material for monitoring trace element deposition in two urban environments.’’] ———, S. Giordano, D. Naimo & R. Bargagli. 2008. Geochemical properties of airborne particulate matter (PM10) collected by automatic device and biomonitors in a Mediterranean urban environment. Atmospheric Environment 42(2): 346–357. [Lichens and mosses trapped air particulates, especially soil dust, in this study around urban Naples, Italy.] Alstrup, V. & U. Sochting. 2008. Hvad blev der af de danske rensdyrlaver og baegerlaver? Lavslaegten Cladonia for og nu. Vaer med til en kortlaegning! Urt 32(2): 75. [Popular note on Cladonia.] Andreev, A. A., D. J. Lubinski, A. A. Bobrov, O. Ingolfsson, S. L. Forman, P. E. Tarasov & P. Moller. 2008. Early Holocene environments on October Revolution Island, Severnaya Zemlya, Arctic Russia. Palaeogeography, Palaeoclimatology, Palaeoecology 267(1–2): 21–30. [Conditions with modern ‘‘sparse lichen-moss-grass cover’’ were established in the region about 9400 years ago as the climate became cooler and drier.] Anonymous. 2008. Secret life of lichens. The Botanics 33: 13. [A short note on a current exhibition in Edinburgh, Scotland, of specimens, photographs, and also paintings by Claire Dalby, and information on human uses as medicine and food.] Aptroot, A. 2008. Sticta alpinotropica, a new saxicolous lichen species from the alpine zone of Mt Wilhelm, Papua New Guinea. Lichenologist 40(5): 419–422. [New: S. alpinotropica sp. nov., known only from the summit region at 3900–4200 m.] ———. 2008. Lichens of St Helena and Ascension Island. Botanical Journal of the Linnean Society 158: 147–171. [Records of 225 species from St. Helena and nearly 100 from Ascension Island. New: Dermatiscum pusillum sp. nov., Dimelaena triseptata sp. nov., Dolichocarpus seawardii sp. nov., Ramalina geniculatella sp. nov., R. ketner-oostrae sp. nov., R. rigidella sp. nov., R. sanctae-helenae sp. nov. and Xanthoparmelia beccae sp. nov.] Archer, A. W. & J. A. Elix. 2008. Three new species in the Australian Graphidaceae (lichenized Ascomycota). Australasian Lichenology 63: 26–29. [New: Acanthothecis aquilonia sp. nov. (Northern Territory), Diorygma wallamanensis sp. nov. (Queensland) and Phaeographis girringunensis sp. nov. (Queensland).] Aznar, J.-C., M. Richer-Lafleche & D. Cluis. 2008. Metal contamination in the lichen Alectoria sarmentosa near the copper smelter of Murdochville, Quebec. Environmental Pollution 156(1): 76–81. [Study of heavy metals (Cu, Cd, Pb, As, Ba). ‘‘Metal concentrations and Pb isotopic ratios in the lichen Alectoria sarmentosa showed a clear spatial pattern related to a point source emission.’’] Bajpai, R. P. 2008. Quantum nature of photon signal emitted by Xanthoria parietina and its implications to biology. Indian Journal of Experimental Biology 46: 420–432. [‘‘The reproduction of photon count distributions is a credible evidence of spontaneous emission of photon signal in a quantum squeezed state for macroscopic time by the sample. It is suggested that every living system is associated with a photon field in a squeezed state. The suggestion has * The cumulative database for this series is available in searchable form on the World Wide Web at http://www.nhm.uio.no/botanisk/bot-mus/ lav/sok_rll.htm. I owe special thanks to Bill Buck for providing copies of papers by other authors, which were otherwise unavailable to me, and to the cooperating authors who send reprints or electronic versions of their works to me for inclusion in this series.

Early Holocene environments on October Revolution Island, Severnaya Zemlya,Arctic Russia

Pollen, palynomorphs, and rhizopods were studied from several < 1 m thick, peaty and silty sediment sections on southwestern October Revolution Island, Severnaya Zemlya. Six AMS radiocarbon ages from the sections show that peat accumulation started at ca. 11,500 and stopped after 9500 cal. yr BP, consistent with several previously reported 14C ages. Open steppe-like vegetation existed on the island during the late Glacial, shortly before the Pleistocene/Holocene transition. Environmental conditions on the island were most favourable for local biota during the early Holocene, ca. 11,500–9500 cal. yr BP, when tundra-like sedge-grass communities dominated the vegetation. Low shrub tundra associations with dwarf birch and willow grew in more wind-sheltered localities. The temperatures during the growing season were at least 4 °C higher than today. The Vavilov Ice Cap was at or behind its present margins. Environmental conditions in the region changed significantly ca. 9400 cal. yr BP as a result of colder and drier conditions, when vegetation became similar to the modern, sparse lichen–moss–grass cover.

Pollen and Isotope Investigations of an Ice Core from Vavilov Ice Cap, October Revolution Island, Severnaya Zemlya Archipelago, Russia

The Vavilov Ice Cap (79°27'N, 95° 21'E) was cored during February and March of 1988. The corer passed through 457.18 m of glacier ice, 2.15 m of moraine-containing ice, and 2.28 m of underlying rocks. Structural-stratigraphical and isotope analysis show the glacier ice is of Holocene in age; the ice layer covered by frozen deposits is Pleistocene glacier ice; and the ground (ice wedge?) ice from underlying sediments was formed during the Last Interglacial. Palynological studies of this core, carried out for the first time in the Russian Arctic demonstrate that the pollen spectra have a unique pattern. It reduces the possibility of correlation between the Vavilov Ice Cape spectra and pollen spectra from other surficial deposits, because the ice retains pollen and spores brought from enormous distances. Only the upper 65 m of the core is easily dated, to the last millennium, by the presence of cereals, Plantago lanceolata, Centaurea cyanus, Cannabis pollen. That is in good agreement with the model of age distribution based upon depth. The presence of considerable amounts of Tilia cordifolia pollen, a West-European species in the upper layers suggests that summer air masses have been dominantly from the southwest during the last 500 years. The pollen data do not contradict the conclusion the Vavilov ice core is composed of a section of Holocene ice, moraine-containing ice representing the Pleistocene episode, and a ground ice formed during an earlier warm period (Last Interglacial?).

New geochronological data on Palaeozoic igneous activity and deformation in the Severnaya Zemlya Archipelago, Russia, and implications for the development of the Eurasian Arctic margin

The Severnaya Zemlya Archipelago, located close to the continental edge of the Kara Shelf in the Russian high Arctic, represents, together with northern Tajmyr, the exposed Neoproterozoic and Palaeozoic part of the North Kara Terrane. This terrane has been interpreted as an independent microcontinent or part of a larger entity, such as Arctida or Baltica, prior to collision with Siberia in Late Carboniferous time. A major stratigraphic break, the Kan'on (canyon) River Unconformity, separates folded Late Cambrian from Early Ordovician successions in one area, October Revolution Island. New geochronological U–Th–Pb ion-microprobe data on volcanic and intrusive rocks from this island constrain the age of an important magmatic episode in the earliest Ordovician. A tuff, in association with Tremadocian fossils, overlying the Kan'on River Unconformity, has been dated to 489.5 ± 2.7 Ma. The youngest rocks beneath the unconformity are of the Peltura minor Zone, and the latter has been dated previously, in western Avalonia, to 490.1+1.7−0.9 Ma. Thus, little time is available for the tectonic episode recorded by the unconformity, and the similarities in radiometric dates may indicate problems with the correlation of faunal markers for the Cambrian–Ordovician boundary across palaeo-continents. The other extrusive and intrusive rocks which have been related to Early Ordovician rifting in the Severnaya Zemlya area yield ages from 489 Ma to 475 Ma. An undeformed granite, cutting folded Neoproterozoic successions on neighbouring Bol'shevik Island has been dated to 342 ± 3.6 Ma and 343.5 ± 4.1 Ma (Early Carboniferous), in accord with evidence elsewhere of Carboniferous strata unconformably overlying the folded older successions. This evidence conflicts with the common interpretation that the structure of the Severnaya Zemlya Archipelago originated during the collision of the North Kara Terrane with Siberia in Late Carboniferous time. An alternative interpretation is that Severnaya Zemlya was located in the Baltica foreland of the Caledonide Orogen and that the eastward-migrating deformation of the foreland basin reached the area of the archipelago in latest Devonian to Early Carboniferous time. This affinity of the North Kara Terrane to Baltica is further supported by 540–560 Ma xenocrysts in Ordovician intrusions on October Revolution Island, an age which is characteristic of the Timanide margin of Baltica.

Biostratigraphical implication of Middle–Upper Cambrian acritarchs from Severnaya Zemlya (high Arctic of Russia)

Lower Paleozoic organic-walled microfossils from the October Revolution Island (Severnaya Zemlya Archipelago) have been investigated taxonomically and biostratigraphically. Four acritarch assemblages allow a stratigraphical correlation of the studied strata with Baltic trilobite zonations from the Paradoxides paradoxissimus trilobite Zone of the Middle Cambrian to the Peltura minor trilobite Zone of the Upper Cambrian. The fifth assemblage is poor and contains neither typical Cambrian taxa, nor Ordovician species of definite biostratigraphical value. The uppermost Cambrian interval embracing at least two trilobite zones ( Peltura scarabaeoides and Acerocare) has not been recognized in the Cambrian–Ordovician succession of the October Revolution Island.

Quantifying the Mass Balance of Ice Caps on Severnaya Zemlya, Russian High Arctic. I: Climate and Mass Balance of the Vavilov Ice Cap

Due to their remote location within the Russian High Arctic, little is known about the mass balance of ice caps on Severnaya Zemlya now and in the past. Such information is critical, however, to building a global picture of the cryospheric response to climate change. This paper provides a numerical analysis of the climate and mass balance of the Vavilov Ice Cap on October Revolution Island. Mass balance model results are compared with available glaciological and climatological data. A reference climate was constructed at the location of Vavilov Station, representing average conditions for the periods 1974–1981 and 1985–1988. The site of the station has a mean annual temperature of −16.5°C, and an annual precipitation of 423 mm water equivalent. The mass balance model was calibrated to the measured mass balance, and tested against the time-dependent evolution of the englacial temperatures (to a depth of 15 m). The mass balance model was then converted to a distributed model for the entire Vavilov Ice Cap. Model results predict the spatial distribution of mass balance components over the ice cap. Processes involving refreezing of water are found to be critical to the ice cap’s state of health. Superimposed ice makes up 40% of the total net accumulation, with the remaining 60% coming from firn that has been heavily densified by refreezing.

Quantifying the Mass Balance of Ice Caps on Severnaya Zemlya, Russian High Arctic. II: Modeling the Flow of the Vavilov Ice Cap under the Present Climate

To understand how ice masses in the Russian High Arctic respond to climate change, the processes that influence their current mass balance must be evaluated. A mass balance model was coupled with an ice-flow model to determine the influence of the present climate regime on the dynamics of the Vavilov Ice Cap, October Revolution Island, Severnaya Zemlya. Model results show that the bulk of the ice cap is flowing relatively slowly, at a velocity of around 5 m a−1. However, the climate regime encourages the ice cap to migrate toward the precipitation source in the southwest. The ice cap may not, therefore, be in equilibrium with the present climate. Given that the response time of the ice cap is of the order of 1000 years, this non-equilibrium may be related to changes in climate that occurred during the Little Ice Age, when the ice cap may have been north of its present position.

The Timanide, Caledonide and Uralide orogens in the Eurasian high Arctic, and relationships to the palaeo-continents Laurentia, Baltica and Siberia

abstract Recent studies of structure, stratigraphy and isotope geochronology on Svalbard and East Greenland have provided a foundation for reconstructing the Laurentian margin of the Arctic segment of the North Atlantic Caledonides. The axial zone of the high Arctic, Barentsian Caledonides has been inferred to trend northwards through the Barents Shelf to the northern edge of the Eurasian margin between Kvitøya (easternmost Svalbard) and western Franz Josef Land, based on analysis of drill-cores that sampled the pre-Carboniferous basement beneath Alexandra Island. The deformation front of the Barentsian Caledonides has been inferred to trend northeastwards between Franz Josef Land and Novaya Zemlya. The North Kara Terrane, reaching from Severnaya Zemlya (SZ) and northernmost Taimyr in the east to northern Novaya Zemlya in the west, comprises the northernmost foreland to the Barentsian orogen. Four lines of independent evidence are presented here demonstrating that the North Kara Terrane is a direct northerly continuation of the Timanide domain, the latter composing the Neoproterozoic accreted margin of Baltica in the Timan-Pechora-Urals region. These lines of evidence, all from October Revolution Island (SZ), include: (1) a westerly source for Old Red Sandstones successions, with 'Caledonian' fish fauna and detrital muscovites yielding Ar/Ar ages of c. 450 Ma; (2) Ordovician igneous rocks containing c. 550 Ma xenocrysts; (3) Cambrian turbidites with c. 545 Ma detrital muscovites; (4) Cambro-Silurian fauna with many species shared with Baltica. In addition, the Neoproterozoic turbidites of northern Taimyr have been previously reported to contain c. 560 Ma zircon populations, a signature that has been recently found in similar lithologies from Bol'shevik Island (SZ). All these late Vendian ages are characteristic of the Timanide Orogen of the Timan-Pechora-Novaya Zemlya region and, together, indicate that the North Kara Terrane was not an independent 'plate' or 'microcontinent' in the Palaeozoic, as previously proposed, but an essential part of southernmost (Ordovician coordinates) Baltica. Comparability of the evolution of the Timanian margin of the North Kara Terrane with the contemporaneous Baikalian evolution of adjacent Taimyr, together with the lack of evidence of Palaeozoic oceanic rocks and Uralian collisional, high-pressure metamorphic assemblages in Taimyr, suggests that the palaeocontinents Siberia and Baltica were never separated by a major ocean in the high Arctic.

Paleozoic history of the Kara microcontinent and its relation to Siberia and Baltica: Paleomagnetism, paleogeography and tectonics

The tectonic history of the Kara microcontinent on the northern part of the Taimyr-Severnaya Zemlya region, Siberian Arctic, has been the subject of considerable dispute, especially with respect to whether it was attached to Siberia or Baltica, or was an independent plate during the Late Neoproterozoic and Early Paleozoic. One way to resolve this controversy is by quantitative paleomagnetic data, and in this article, we present the results of a paleomagnetic study of Early Paleozoic strata from October Revolution Island in the Severnaya Zemlya Archipelago, which allow definition of the paleogeographic position of the Kara microcontinent during the Early Paleozoic. Paleomagnetic poles for three consecutive time intervals, i.e., Late Cambrian–Early Ordovician, Middle–Late Ordovician and Late Silurian, have been determined. These new data demonstrate that Kara was not part of Siberia or Baltica during the Early Paleozoic, but support models that it was an exotic microcontinent with an independent tectonic history. The Paleozoic tectonic evolution of the Kara microcontinent was dominated by strike–slip displacements associated with a transform margin that resulted in collision with the Siberian craton in the Late Carboniferous to Permian. This interpretation provides a new foundation to explain the Paleozoic history of the Kara microcontinent.

Integration of Corona and Landsat Thematic Mapper data for bedrock geological studies in the high Arctic

The Severnaya Zemlya Archipelago near the continental edge in the Russian high Arctic is one of few land areas along the Eurasian Arctic margin. It is of particular interest for investigating the Arctic's tectonic history. This study focuses on the Palaeozoic bedrock of October Revolution Island. In the Russian high Arctic detailed topographic maps and aerial photography often are not available. The potential of low-cost satellite imagery as a substitute is shown in this study. High-resolution Corona KH-4A panchromatic satellite imagery and Landsat Thematic Mapper (TM) multispectral data have been integrated. In combination with field investigations in key areas, these data provide the basis for new interpretations of the geology. Corona images were digitized and georeferenced to provide a basis for conventional and digital geological mapping. Merging Corona and Landsat TM data resulted in a high-resolution multispectral image of enhanced interpretability. Lithological contacts have been traced, supported by a bedrock image extracted from the Landsat TM data. Stereoscopic coverage of the Corona KH-4A photographic sensor allowed a structural interpretation. All results were integrated into a geological interpretation of southern October Revolution Island which provides an encouraging platform for further work in the high Arctic.

Arthropods from the Lower Devonian Severnaya Zemlya Formation of October Revolution Island (Russia)

Arthropods from the Lower Devonian Severnaya Zemlya Formation of October Revolution Island (Russia)

New corvaspids from the Lochkovian (Lower Devonian) of Severnaya Zemlya, Russia (Vertebrata: Pteraspidomorphi: Heterostraci)

ABSTRACT The new genus and species Corveolepis elgae is described from the Lochkovian, Severnaya Zemlya formation of October Revolution Island, Severnaya Zemlya. It is ascribed to the family Corvaspididae whose diagnosis is corrected. Corvaspis arctica Loeffler and Dineley is designated as the type species of Corveolepis. Previously described taxa such as “Corvaspis kingi” auct. and Corvaspis graticulata Dineley from Spitsbergen are included with doubt in Corveolepis. Other new material includes Corveolepis? sp. cf. C.? graticulata from the Lochkovian, Pod'emnaya formation of October Revolution Island. This material is used as supporting evidence for a correlation of Lower Devonian vertebrate-bearing strata between Severnaya Zemlya and Spitsbergen.

New data on the Silurian of Severnaya Zemlya, Russian Arctic

Recent stratigraphic investigations on October Revolution Island (Severnaya Zemlya) have revealed the presence of Silurian terrigenous-carbonate deposits with rich faunas of graptolites, cephalopods, ostracodes, brachiopods, gastropods, and bivalves. The graptolites indicate a mid Telychian (late crispus-griestoniensis Zone) age for the strata bearing them.