A detailed geomorphological mapping allowed to understand the complex relationships interplayed between local tectonics and sedimentation across the coastal area of the Baixo Alentejo (Portugal) all along the Quaternary. Different outcrops of coastal sediments between Sines and Vilanova de Milfontes permitted to reconstruct a general sequence of up to fifteen stair-cased marine terraces, while wide sequences of alluvial fans develop in the hinterland. The distinct geomorphological disposition of these alluvial fans together with the presence/absence of marine terraces, have allowed to define different phases of paleolandscape evolution based both in sea level changes and differential uplift. A dune system has been attributed to MIS 5e in basis of OSL, and C-14 and U-series dating permitted the adscription of a beach unit to MIS 5. These data allowed to stablish the relative chronology of the entire marine terrace sequence and to determine the vertical movement rates along the studied coastal area. The results give values ranging from slight uplift (+0.015mm/a) to subtle subsidence (-0.030 mm/a), coinciding with other author's determinations.
A detailed analysis of the Viñales National Park (VNP) was carried out to evaluate the main geosites of geomorphological interest inside the park. This allowed the selection of areas (AIG) and localities (LIG) with 20 geosites of geological interest (PIG) suitable to evaluate their importance as geoheritage. Moreover, three field trips and one virtual itinerary encompassing the park aimed to improve the geological–geomorphological knowledge to be used in geotouristic and preservation issues. The methodology included preparing five maps: relief, drainage pattern, slopes, lithology and geomorphology (forms and structures) and representing them on a digital terrain model (DTM) for a better visualisation and selecting the geosites (poljes, valleys and mountain fronts). The evaluation of the selected PIG is based on the criteria proposed by Spanish Institute of Geology and Mining, grouping them in places and areas of interest. The virtual itinerary favour real-time usage of web sites and geoportals. As a result, this paper presents map layers and geomorphological descriptions of the AIG and LIG with the most relevant aspects and valuations of the PIG, AIG and LIG. The PIG reached values between 1050 (Viñales Valley) and 365 (La Jutia Valley). The AIG and LIG ranged between 2190 (Santo Tomás Polje) and 675 (La Cuevita Polje).
Along the northern littoral of the Iberian Peninsula, from Cuerres (Asturias) to Oyambre (Cantabria) there are caves, such as El Pindal (World Heritage List). Two geomorphologic maps have been prepared: a general scaled 1:25000, and a detail one of the cave, with erosional and depositional landforms geomorphologic units. A relative Quaternary chronology for the depositional landforms, uses colour spots. Marine morphologies suitable for determining past sea-level positions were surveyed to identify the elevation of past high-stands and reconstructing paleo-shorelines. As a result, the study of seven erosional surfaces (rasas) in quartzites and six on limestones led to reconstructing a general sequence between 275-120 m and 90-1 m above sea level (a.s.l.) respectively. Around the El Pindal cave there are four rasas cut on quartzites (171-160 m) and four cut on limestone (65-32 m). Other additional indicators of paleoshorelines are: 24-25 m entrance to the El Pindal cave, 20-21 m lower Pindal, 15-17 m marine terrace, 9-10 m shelter, 2-3 m notches and 0-1 m present rasa. Considering the elevation rates for the various rasas, an estimated value of 0.066 mm/y as the most probable, it is concluded that the beginning of Quaternary lays at 172 m a.s.l.
The study of the Peña Negra paleoglacier during the Last Glacial Maximum reveals its sensitivity to paleoclimatic variations. The evolutionary phases of the paleoglacier are correlated with the evolutionary models proposed for the Sierra de Béjar-Candelario and the Central Iberian System. To recognize the mechanisms of ice advance/retreat and the response of the glacier to paleoclimatic variations, modeling is carried out based on a geographic information system tool. This model is key to establishing the spatial extent of the ice and the estimation of the Equilibrium line altitudeequilibrium line altitudes at each moment, which makes it easier to infer the approximate climatic conditions of each phase (temperature and precipitation) and allows us to improve the understanding of the glacial dynamics versus variations in paleoenvironmental conditions and paleoglacial morphometry. The spatial reconstruction data show that the paleoglacier had 0.526 km3 of ice during the phase of maximum extension, while the paleoclimatic data reflect an increase in precipitation and a slight decrease in average summer temperatures compared to today. The stability phases are associated with the periods of greatest precipitation when the mass balance was positive.
A sedimentary sequence covering the entire last glacial cycle (period between Terminations I and II) outcrops along the south-eastern coast of Formentera Island. A detailed geomorphological, geological and sedimento-logical study, supported by geochemical, soil and soil-morphology analyses, magnetic susceptibility, phytolite content and luminescence dating (TL, OSL) allowed to reconstruct the environmental evolution of this coastal setting, and to frame it within the evolutionary pattern of the North Atlantic climate variability. Three highstands of sea level are identified in this island for MIS 5e, and a fourth one is attributed to MIS5a. MIS5 - MIS4 transition is characterized by soil development under a moist-warm climate and a descending sea level scenario. Aeolian units (72 +/- 7 ka BP) developed during MIS4 under prevailing northerly winds that persisted until the beginning of MIS3, when new aeolian dunes (54 +/- 5 ka BP) developed after a major sea-level lowstand. A sudden shift in prevailing winds occur within MIS3, when aeolian units (51 +/- 4 ka BP) grew under the influence of S-SW winds and moister climate, evidenced by a dense root bioturbation. The greater influence of northerly winds is attributed to the weakening of Atlantic Meridional Overturning Current (AMOC) in North Atlantic, and enhancement of westerlies in NW Europe during colder periods. Periods of prevailing southerly winds and moister climate correlate well with warm Greenland Interstadials, and reinforcement of AMOC. Between 50 and 40ka, alluvial/colluvial sedimentary units punctuated by soil and calcrete development, witness the climatic variability recorded along this period in the North Atlantic. A sedimentary hiatus with erosion and calcrete development characterizes the transit between MIS3 and MIS2. Finally, a reddish alluvial sedimentary unit re-cords a short span of humid and warm climate (soil development, peak in magnetic susceptibility, phytolite content) within MIS 2 (20 +/- 2 ka BP - 17 + 2.4/-2.2) that contrast with the general climatic trend recorded in Western Mediterranean during the Last Glacial Maximum.
The dune fields of the National and Natural Parks of Doñana are considered one of the most outstanding dune fields in Western Europe. They are located at the west margin of the Guadalquivir river estuary. The accumulation of aeolian sands partly blocks the connection between the ample Guadalquivir River estuary and the Gulf of Cádiz in the Atlantic Ocean. The sand units form a large oval dome, the "Abalario Dome" which connects with the large Doñana Spit Bar where dune systems accumulated as well, at least in part coevally with the spit growth. The most frequent dune morphologies are parabolic or transverse. The degree of activity was classified as stable, semi-active and active. Most stable dunes concentrate on the Abalario Dome, whereas active dunes occur mainly on the Doñana spit bar. Relative chronology was established from the superposition of dune Systems and Subsystems deduced from photogeology coupled with field surveys, orthophotos, and oblique and 3D images. Sampling and radiogenic dating (Optically Stimulated Luminescence-OSL) allowed to date eight dune Systems named as Systems I to VII plus an additional CS, which is a laterally equivalent to part of S IV, V and VI. The proposed ages are: System I, age 11.1 38 to 9.5 ky BP, perhaps extending to 8.5 ky BP. System II, 8.2 to 6.1 ky BP. System III, 5.9 to 2.6 ky BP. 39 System IV, 2.6 to 1.6 ky BP. System V, 1.6 to 1.3 ky BP. System VI, 1.2 to 0.7 ky BP. System VII, 0.7 to 40 0.15 ky BP. The age of the Complex System is 2.2 to 0.15 ky BP. Additionally, it was concluded that genesis of the somewhat-different Complex System (CS) was related to the increased accumulation space created by movements (sliding) along the Mazagón and Torre del Loro faults following major regional seismic activity.
This article identifies, describes, and characterizes, based on the analysis of 20 geosites, the geological heritage of the Béjar and El Barco massifs. Using 22 characteristics, and weighting coefficients, these geosites were qualitatively and quantitatively assessed (representativeness, accessibility, etc.) and classified into different groups depending on their extension (area, location, and points of geological interest) and potential use (scientific, didactic, tourism, and recreational). Consequently, 9 geosites were selected, owing to their importance and noteworthiness, and the geodiversity index (GI) was calculated using parametric cartographies (geomorphological units, lithology, vegetation and land uses, orientations, and slopes). The abundance of elements present within a given surface area was analyzed for each homogeneous territorial unit, defined by the specific geological, geomorphological, and natural environmental context being analyzed within the study area. Our results show that sites of geomorphological interest (SGI) have great importance and notoriety in relation to the glacial, periglacial, and fluviotorrencial events that occurred during cold periods and deglaciation. Moreover, a GI value of 24.38 was recorded for the highest areas due to the diversity of geoforms and current processes. The information obtained in this work could prove useful in the improvement of geosites, as it would allow geological heritage to be considered at the time of establishing plans for sustainable geoconservation.
A 3D virtual geological route on Digital Earth of the geological-geomorphological and paleontological heritage in the Algarve (Portugal) is presented, assessing the geological heritage of nine representative geosites. Eighteen quantitative parameters are used, weighing the scientific, didactic and cultural tourist interest of each site. A virtual route has been created in Google Earth, with overlaid georeferenced cartographies, as a field guide for students to participate and improve their learning. This free application allows loading thematic georeferenced information that has previously been evaluated by means of a series of parameters for identifying the importance and interest of a geosite (scientific, educational and/or tourist). The virtual route allows travelling from one geosite to another, interacting in real time from portable devices (e.g., smartphone and tablets), and thus making possible the ability to observe the relief and spatial geological distribution with representative images, as well as to access files with the description and analysis of each geosite. By using a field guide, each geosite is complemented with activities for carrying out and evaluating what has been learned; these resources allow a teaching–learning process where the student is an active part of the development and creation of content using new technologies that provide more entertaining and educational learning, teamwork and interaction with social networks. This itinerary allows the creation of attitudes and skills that involve geoconservation as an element for sustainable development.
From the geomorphological cartography, the geometric and spatial distribution of the quaternary forms and deposits are analyzed, with special relevance to the fluvial terraces that allow obtaining the chronology of the successive landscape changes of the course of the Tagus River attributed to the activity of the Fault of Alentejo-Plasencia (APF). The “Appalachian” relief of Monfragüe National Park, constituting a series of quartzitic combs with direction NW, between which they find slopes, hills and valleys following the same direction, for the dismantlement of the Cenozoic cover that was covering the substratum (still present in the central sector) and encasement of the Rivers Tagus and Tiétar. The remains of fluvial terraces inside and outside the Park stand out at different heights and so they originate from different times and show different landscapes along the routes of the Tagus river and its movement over time. In the north end (basin of the Campo Arañuelo), there are remains of ten fluvial terraces of relative importance attributed to the River Tagus (with heights relative to the thalweg between 120 and 20 m). In the south edge, there are eight levels attributed to a former fluvial drainage network, which assimilates to the River Tagus, with the more recent level reaching over 280 m on the current river. Neotectonics readjustments that rejuvenated the relief produced the elevation of the socle and cover, at the time of diversions in the path of the fluvial network, up to the structure and encasement (for supertax and/or antecedence). During the Quaternary, the activity of the Alentejo-Plasencia Fault (APF) has given rise to palaeogeographic changes in the fluvial valley of the Tagus River. During the ancient Lower Pleistocene, its course passed south of the current one (Talaván-Torrejón el Rubio basin); at the end of the Lower Pleistocene, it came out crossing the syncline through the Boquerón porthole, and the meander that bordered the town of Almaraz was abandoned; at the beginning of the Middle Pleistocene, it changes its direction, from NE–SW to SE–NW, leaving the porthole and joining the Tiétar river within the Park; later it moves somewhat to the south. These changes in the route and the anomalous fitting of the course of the Tagus River into the Paleozoic substrate, have been attributed to the APF, which, through impulses, has had a great activity from the Lower Pleistocene to the Middle Pleistocene.
The volcanic Cape Verde archipelago constitutes one of the few sites in low latitude eastern Atlantic Ocean, where a long record of Pleistocene sea-level indicators develops, particularly beach deposits and marine terraces. The extreme aridity of the easternmost islands (Sal, Boa Vista and Maio) allows the exposure of long sedimentary sequences, the altitudinal and spatial distribution of which must be related both to sea level behaviour in low latitude settings and also to the volcanic nature of the archipelago. The particular case of Maio Island reveals the occurrence of a flight of at least 18 marine terraces, between +85 and 0m. The chronology has been approached by a paleomagnetic sequence (Early - Middle Pleistocene transition), U-series measurements (Last Interglacial deposits) and 14C (Holocene units). The results have revealed a differential behaviour in the vertical motion of the island along the Pleistocene, with unequal uplift rates during Early and Middle Pleistocene. An anomalously low-lying MIS5 unit in this island fits well with the predictions done by GIA models of Crevelling et al., (2017) although the proper evolution of volcanic islands cannot be discarded. A comparison with Sal (Zazo et al., 2007, 2010) and Boa Vista islands is done, especially in what the MIS5 sea level record is concerned. MIS 5e deposits are scarce along the coasts of Maio and Boa Vista, and always at very low heights above mean sea level (0-0,5 m). On the island of Sal the deposits corresponding to the MIS 5e are located at a maximum height of +2.5m asml, in its most southern sector, being also very frequent to find them at 0m (Zazo et al., 2010). The geomorphological distribution of the Pleistocene sedimentary sequences along these three islands reveals a complex history of uplift and subsidence that must be conciliated with the far-field sea level behavior, especially for the MIS5 units. Creveling et al., 2017. QSR 163. Zazo et al., 2007. QSR 26. Zazo et al., 2010. GPCh 72. Acknowledgements: This work has been supported by FEDER-MINECO Spanish project CGL15-69919-R.
The recent geodynamic evolution of Iberia is recorded in its topography. Geomorphic markers and their dating; morphometric indices estimated through cutting-edge DEM analysis techniques; and the link of all this data with results of geophysical studies allow discussing why Iberia displays the highest average elevation in Europe and shows a particular topography with such diversity of landscapes. For example, the region of the Iberian (or Hesperian) Massif, the western sector of Iberia, shows an anomalous average elevation without a satisfactory explanation. On the other hand, different explanations about the recent evolution of the Alpine mountain ranges of the eastern sector of Iberia have come to light after macroscale landscape analyses. This is strengthening the debate on the driving force behind the actual topography of the Pyrenees, Cantabrian Mountains, Iberian Chain and Betics.
From a large database generated from the geological heritage of more than 100 geosites in four natural areas of Salamanca, Ávila, and Cáceres provinces (Spain), the 13 most representative sites were selected, and their scientific, educational, and tourist/cultural interest values were determined. The natural park of Batuecas-Sierra de Francia-Candelario presents the highest values and is followed by the natural park of Arribes del Duero. Using geomatic tools, digital information was compiled from different thematic layers, and, together with photographs, diagrams, and descriptive cards, was incorporated to produce didactic resources. By interacting with digital information using the free Google Earth platform, 3D virtual flights, which can be followed in real time, were established and implemented in different formats (mpeg, avi, wma, etc.). These are reproducible in different multimedia systems, which increases the possibility of educational and tourism use by broad layers of the population. Therefore, this favors the sustainable development of the area.
This paper presents a geomorphological analysis of the Tormes River during the Quaternary. The Tormes River formed in the center-west of the Iberian Peninsula in the province of Salamanca. It runs along a Cenozoic basin with basement materials and through Varisco, and consists of mainly granitic and metamorphic materials, leaving a wide stream of river terraces, both erosional and depositional, that confirm its evolution throughout the Quaternary. Geomorphological analyses using Geographic Information Systems tools, Digital terrain model high resolution (MDT05, LIDAR), Orthophotos (scale 1:5000), and geological maps (1:50,000 Series Magna) have allowed different morphologies and depositional terraces to be distinguished, namely, 19 levels of erosional terraces and 3 levels of erosion surfaces. Based on these correlations, the levels of terraces in the Tormes River between T1 (+140 m) and T7 (+75–80 m) are located in the Pleistocene, those between T8 (+58–64 m) and T14 (+18–23 m) in the Middle Pleistocene, those between T15 (+12–13 m) and T17 (+6–7 m) in the Upper Pleistocene, and those between T18 (+3 m) and T19 (+1.5 m) in the Holocene. The erosion surfaces are divided into six levels: S6 (+145 m), S5 (+150 m), S4 (+160 m), S3 (+170 m), S2 (+180 m) and S1 (+190 m) located in the Lower Pleistocene, This work performs a geomorphological mapping procedure applied to the evolutionary analysis of the landscape, so that it determines different geomorphological units allowing the relief and morphology of the terrain in past times, establishing a dynamic analysis of the landscapes.
This article analyzes the coastal vulnerability and flood risk due to sea level rise in the Menor Sea, Murcia (Spain). The vulnerability has been estimated from Sentinel-2 and Landsat 8 satellite imagery using Remote Sensing techniques. The risk of coastal flooding was calculated based on various time scenarios (X-0-current, X-1-100 years, X-2-500 years, X-3-1000 years, X-4-Storm, X-5-Tsunami). Geographic Information System and Remote Sensing techniques were used to build a regional model to predict changes in the mean sea level for several future scenarios, showing susceptible areas to be flooded. We have included new parameters to the model such as swell, mareal range or neotectonic factors aiming to better adjust it to the local conditions. The results showed a high risk of flooding in the barrier beach and coastal areas of the Menor Sea, with a medium to very high degree of vulnerability for the most populated and touristic areas. The maximum and minimum expected increase of the water sheet for the 100 year scenarios ranged from +4.22 to +5.69 m. This methodology can establish sectors that need structural measures to minimize the impact of the sea level rise occurring due to natural tendency in the short or long term, as well as by extreme events such as storm surges or tsunamis. Furthermore, it can be used in other areas to assist land management decision makers to reduce or mitigate the vulnerability and risk presented against the rise of the sea level.
This paper presents a geomorphological analysis of the littoral zone of the Arosa-Pontevedra estuary mouth and identifies geomorphological units and categorizes them into morphogenetic systems. The different morphogenetic systems are used to establish a comprehensive evolutionary analysis, contrasting the depositional systems found in the continental littoral zone with the marine erosional systems ('rasas'). The compiled cartography groups the geomorphological units into the following: the lithoestructural morphogenetic system with large-scale forms (domes, inselbergs, residual relief, etc.) and small-scale forms (gnammas, tafoni, channels, etc.); the littoral morphogenetic system comprised of marine (marine terraces, beaches, tidal bars, tombolos and coastal arrows), transition (marshes, lagoons and fan deltas) and eolian (dune systems) settings; the fluvial morphogenetic system with channelled (alluvial, flood plain and river terraces), transition (alluvial fans and alluvial cones) and sheet flood (pediments and glacis) systems; the gravitational morphogenetic system (colluvium); and the alteration morphogenetic system (sand-alteration).
ResumenEste trabajo presenta una síntesis de la estratigrafía y geocronología del Periodo Cuaternario tras la actualización cronoestratigráfica aprobada por la Comisión Internacional de Estratigrafía (ICS-IUGS) y la Unión Internacional para el Estudio del Cuaternario (INQUA). Se aportan los datos más recientes sobre estratigrafía, cronología y paleoclimatología de este periodo en la Península Ibérica, así como los esquemas o fuentes bibliográficas más clásicas. Se da una visión general de la Prehistoria enmarcándola dentro de los episodios o eventos climáticos más característicos del Pleistoceno final, Holoceno y Antropoceno. Esta síntesis pretende ser una guía resumida de la cronología cuaternaria para todos aquellos investigadores que, trabajando en el Periodo Cuaternario, no poseen una formación científica adecuada al respecto.
This work presents a synthesis on the stratigraphy and geochronology of the Quaternary Period after the chronological updating ratified by the International Commission on Stratigraphy (ICS-IUGS) and the International Union for Quaternary Research (INQUA). We show the more recent (updated) stratigraphic, chronologic and paleoclimatic data regarding to the Iberian Peninsula, as well as the classical approaches and bibliography for these subjects. We offer a general view on the Prehistory in the framework of the more characteristic climatic episodes or events in the environs of the Iberian Peninsula during the upper Pleistocene, Holocene and Anthropocene. This synthesis wants to be a summarized guide of the Quaternary chronology for all those people working in the Quaternary Period without a proper scientific knowledge on the topic.
Geomorphology is fundamental to landscape analysis, as it represents the main parameter that determines the land spatial configuration and facilitates reliefs classification. The goal of this article is the elaboration of thematic maps that enable the determination of different landscape units and elaboration of quality and vulnerability synthetic maps for landscape fragility assessment prior to planning human activities. For two natural spaces, the final synthetic maps were created with direct (visual-perceptual features) and indirect (cartographic models and 3D simulations) methods from thematic maps with GIS technique. This enabled the creation of intrinsic and extrinsic landscape quality maps showing sectors needing most preservation, as well as intrinsic and extrinsic landscape fragility maps (environment response capacity or vulnerability towards human actions). The resulting map shows absorption capacity for areas of maximum and/or minimum human intervention. Sectors of high absorption capacity (minimum need for preservation) are found where the incidence of human intervention is minimum: escarpment bottoms, fitted rivers, sinuous high lands with thick vegetation coverage and valley interiors, or those areas with high landscape quality, low fragility and high absorption capacity, whose average values are found across lower hillsides of some valleys, and sectors with low absorption capacity (areas needing most preservation) found mainly in the inner parts of natural spaces: peaks and upper hillsides, synclines flanks and scattered areas. For the integral analysis of landscape, a mapping methodology has been set. It comprises a valid criterion for rational and sustainable planning, management and protection of natural spaces.
This work performs a geomorphological mapping procedure applied to the evolutionary analysis of the landscape, such that it groups different geomorphological units photointerpreted in large geomorphological domains. This allows greater utility and ease of identification and application in the different multidisciplinary studies of environmental geology and the evolution of the landscape. Geomorphological analysis allows the investigation of the reconstruction of the relief from the processes that have shaped the landscape over time. This work is a tool for the analysis of palaeolandscapes and palaeoreliefs applied to correct environmental and sustainable planning of the territory. The process starts from a morphostructural zoning in which they are grouped according to their erosive and depositional forms and the morphogenetic system to which they belong: structural, fluvial, gravitational, and polygenic. The procedure is applied to two natural parks: Batuecas and Quilamas, differentiating 18 geomorphological domains. The 2D and 3D cartographies have been implemented in virtual 3D balloons allowing a greater ease of landscape analysis in the spatial distribution of the different units over orthophotographs. The morphological and chronological evolution of the evolution of the landscape is established from the relative age of the lithological units and the geomorphological domains, as well as by their geospatial position. Georeferenced digital mapping complies with the Inspire directive for these natural spaces.
This work establishes a mapping procedure to determine the risk of susceptibility to hillside movements (landslides) that can be applied to any territory by means of algebraic mapping of the passive or determining factors that influence risk. On the one hand, derivative morphometric mappings obtained from a Digital Terrain Model that notably influence the genesis of active processes have been generated; these mappings include gradient mapping, aspect mapping and type of curvature mapping. On the other hand, the basic thematic maps that characterise the materials susceptible to being mobilised have also been generated; these include domain geomorphologic mapping, lithological mapping, hydrogeological mapping and vegetation mapping. The result is a map of landslide susceptibility, for which five degrees of risk susceptibility have been, established (very high, high, medium, low and very low). Overlaying the inventory mapping of the hillside movements in two natural spaces of the Central Spanish Mountain System on the landslide susceptibility map validated the procedure when existing slides were found to be in the Very High and High susceptibility sectors of the validation map. This procedure is effective and inexpensive, which makes it very useful during the initial stages of the planning and management of natural spaces.