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This study presents the characterization and chronology of the Quaternary terrace sequence developed in the confluence zone of the Júcar and Cabriel river valleys. The study area covers a radius of 10 km from the confluence of the two valleys near the locality of Cofrentes (Valencia). It is located in the northern zone of the Ayora-Cofrentes Graben in the northeastern sector of the External Prebetic Zone adjacent to southern Iberian Chain. This N-S graben is an inherited tectonic feature with an axial salt wall subject to different periods of fluvial dissection and refilling since at least the end of the Messinian Salinity Crisis (MSC). Regional isostatic uplift and local uplift and subsidence processes related to salt flow and dissolution during the Quaternary period, favored by fluvial entrenchment and terrace development. The terrace system and the previous pre-incision erosional and depositional surfaces are analyzed from a geomorphological point of view. The terrace system only develops within the soft Mio-Pliocene sedimentary fill of the graben, whilst upstream and downstream this zone the studied valleys develop important gorges (canyons) carved in the Cretaceous tablelands (Caroch Massif) and Mio-Pliocene deposits (Llanura Manchega). The geochronological control is established from 20 numerical ages obtained by different dating methods, such us Electron Spin Resonance (ESR), Optically Stimulated Luminescence (OSL) in detrital sequences and Th/U series in calcareous tufa deposits. Additionally, four K/Ar dates available for volcanic materials disrupting the upper and oldest terrace have been considered. A total of 14 terrace levels were identified between +130–135 m (T1) and +3–4 m (T14) of relative height above the river thalwegs. The T1 has an approximate age of c. 1.6–2.0 M.a. as indicate the age of the volcanic materials from the Agras Volcano intruded in the terrace, marking the onset of Quaternary fluvial dissection in the zone. The obtained geochronological data indicate that the Lower-Middle Pleistocene boundary is slightly above T6 (+60–65 m), which has an ESR age of 577 ± 43 ka. This terrace also documents the onset of the most important period of rise of the salt within the graben interfering drainage development. The geochronological data indicate the occurrence of a second eruptive event during the second half of the Middle Pleistocene related to the terraces T7 (+50 m) and T8 (+35–40 m), updating the volcanic activity in the zone. The beginning of the Upper Pleistocene is recorded by the top sequences of the T9 terrace (+25–30 m) where numerous OSL and Th/U data have been obtained with ages between ca. 105 and 81 ka (MIS 5). However, these young terraces (T8 to T13) are thickened (8–10 m) recording Middle Pleistocene sediments in their basal sequences with ages between ca. 193 and 137 ka (MIS 6). The study provides important data on valley evolution under the interference of volcanic activity, salt –related deformation (diapirism, solution subsidence) and fluvial incision fostered by the rise of the axial diapir (salt wall) protruding the graben since at least the Brunhes-Matuyama boundary. The analyzed fluvial evolution documents interesting cases of river capture, drainage antecedence and tectonic adaptation of the drainage throughout the Quaternary Period. The paper also poses interesting geochronological data on the long-term Quaternary evolution of Mediterranean valleys in the Iberian Peninsula, poorly explored to the date. [Display omitted] • The evolution of the Júcar Fluvial system (Spain) is addressed for first time supported. • The catchment contains a complex sequence of 14 terrace levels up to +135 m • Terrace sequence is dated within the last 2.0 Ma using K/Ar, Th/U, OSL and ESR data. • Phreatomagmatic activity disrupts valley evolution during the Lower-Middle Pleistocene • Cases of river capture, drainage antecedence and tectonic superposition are documented [ABSTRACT FROM AUTHOR]

This study presents a multidisciplinary approach to the tectonic geomorphology and history of the Palomares strike-slip fault in the Eastern Betic Cordillera (SE Spain). Analysis combines geomorphological mapping of fan-surfaces, pedological studies of faulted sedimentary successions, geoelectrical prospection and typical paleoseismological routines of structural analyses. Combined application of these methods together with the existing geochronological databases offer probable paleoclimatic and paleoseismic scenarios for the zone from Middle Pleistocene to Holocene. This study segments the Palomares Fault (PLF) in three overlapping "en echelon" N–S trends (PLF1, PLF2, PLF3). The older PLF1 controls the main faulted Almenara-Almagro range fronts. The younger PLF2 cuts and beheads crusted fan surfaces in the Aljibejo zone (ABJ). The intermediate PLF3 controls the development of intervening tectonic reliefs and offset paleosol sequences in alluvial-colluvial deposits. Our analysis focuses on the PLF3 at the La Escarihuela site (ESCH), where outcrops display eight faulted paleosols developed on overlapped Middle Pleistocene colluvial-alluvial deposits, with variable vertical slip of between 21 and 12 cm (bulk accumulated offset: 33 cm), evidence of two surface faulting events. After the structural analysis of the fault planes (striae plunges) net left-lateral displacements of 120.9 ± 3.3 cm (Event 1) to 69.1 ± 5.2 cm (Event 2), associated with maximum magnitudes of c. 6.7–6.5 Mw. However, the faulted sequence is sealed by a thick mature calcrete horizon of similar characteristics to that faulted at the ABJ1 site. Regional chronological data on calcic soils and calcretes in SE Spain assign this mature calcrete to Oxygen isotopic stages (OIS) 9 (c. 300 ka). With this age fixed at the uppermost of the faulted paleosol sequence at the ESCH site (PLF3), soil development features (clay and carbonate contents, thickness, reddishness, etc.) were used as paleoclimatic proxies to correlate soil horizons with conventional OIS. Correlation indicates that clayey Bt soil horizons primarily occurred during warm isotopic stages followed by recalcification and carbonate accumulation (Btk; Bk; Ck horizons) during latter warmer stages. A proposed theoretical geochronological framework suggests that the sedimentary sequence at the ESCH site (PLF3) was deposited between OIS 18 and 9. Major environmental change towards the present semi-arid climate occurred during OIS 13 (c. 500 ka). During this same stage, paleoseismic event 1 also occurred, but paleoseismic event 2 took probably place during OIS 10 (c. 350 ka), before development of the uppermost calcrete sealing the deformation in this fault segment. However, this OIS 9 calcrete is faulted in the ABJ1 and a younger less developed calcrete is faulted in ABJ2 on the PLF2 segment. Chronology proposed in this paper suggests theoretical ages for these events of between OIS 8-OIS 5 for ABJ1 (c. 200 ka) and between OIS 4 -OIS 2 for ABJ2 (c. 40 ka). This last paleoseismic event triggered major landscape changes with still-visible fault scarps, linear tectonic reliefs, alluvial fan beheading and active drainage shuttering. This present work illustrates the use of soil/paleosol analyses in paleoseismology as a useful tool to build paleoclimatic analogues and develop relative chronological frameworks from existing regional age data. • Geomorphology of faulted paleosol sequences allows exploration of tectonic landscapes. • Paleosols are used as proxies to build OIS-based geochronological analogues. • The used methodology analyzes past surface faulting seismic events in SE Spain. • Proposed geochronological analogues allow the relative dating of past earthquakes. • Use of paleosol sequences as a valuable tool in paleoseismic investigations. [ABSTRACT FROM AUTHOR]

This paper explores the use of trenching and paleoseismological techniques to determine salt flow rates into a salt diapir for the first time in the literature. The Salinas de Oro diapir, located in the northern Spanish Pyrenees, is an oval-shaped Triassic-salt stock that extends vertically for ≫7 km down to the Paleozoic basement. Salt dissolution subsidence and diapir growth are coeval active processes. Karstification is responsible for the development of large sinkholes, a thick caprock and the monocline folding and ring faulting of the Cretaceous and Early Tertiary limestone rim. The evaporite karstic aquifer discharges high-concentration water of up to 137 g/l of total dissolved solids and a conductivity over 200 mS/cm into the Salado Creek, which drains the diapir top. The salinity monitoring of this drainage provides a maximum karstic surface lowering rate of around 2.8 mm/yr. Salt upwelling has caused the 150 m uplift of the annular limestone escarpment and the development of ≫3000 m long radial grabens with up to 90 m of vertical offset that disrupt drainages, displace Quaternary deposits and overprint concentric faults. The 260 cm drag folding of lacustrine facies exposed in a 42 m long and 6.5 m deep trench due to the creep motion of the western radial fault of Azanza Graben yielded a minimum short-term uplift slip rate of 1.75 mm/yr for the last 1485 years and provides a minimum salt supply rate of over 5 mm/yr considering karstification lowering. This value that is several hundred times higher than average, evidence the discontinuous growth of Salinas de Oro diapir. • The geomorphology of salt diapirs mainly depends on the uplift/subsidence ratio. • The minimum growing rate of Salinas de Oro diapir is currently higher than the maximum karstic lowering rate. • The AMS dating of exposed sediments in the hanging-wall of a radial fault evidences the episodic growth of the diapir. • The trenching of radial faults is a useful technique to measure the net growing rate of salt stocks in continental settings. [ABSTRACT FROM AUTHOR]

Gully width (W) is usually characterized by having a power relation with discharge. However, calculating runoff discharge in ungauged basins, where these gullies typically form, is inherently difficult and associated with large uncertainties. This paper examines a simplified approach to relating gully width directly to the runoff contributing area (A) in a cultivated area in SW Spain. The effect of rainfall and land use on this W-A relation was also analysed. Gully width was measured in 46 sections through the analysis of 10 historical orthophotos between 1956 and 2013, in a 21 km2 catchment in S Spain. These were validated by field measurements in 2013. Widening rates varied strongly over time, at between ~0 and 2,19 m year−1. No significant differences in the gully widening rates were found between the two land uses present in the study zone (olive groves and herbaceous crops). The data obtained show a significant power relation of the form W = αA β for all time periods analysed, except for 1980, when many gullies were filled in artificially due to a change in land use in the study area. The power relation coefficient (β) varied at between 0.2 and 0.3. A good correlation was obtained between the number of days with daily rainfall of above 13 mm and the increase in the α coefficient over time. The results of this study on gully width dynamics provide new insights into improving the estimation of gully volume, for example in combination with gully headcut retreat models, and including the effects of different climate scenarios. • Gully width dynamics were reconstructed from aerial orthophotos in Mediterranean crops. • We found a significant correlation between gully width and runoff contribution area. • Gully widening rates were successfully correlated with a rainfall index based on daily rainfall thresholds. [ABSTRACT FROM AUTHOR]

The scientific literature describes two types of cheniers. These two types differ in the origin of the coarse sediments that constitute the ridge and the relative significance of the transversal and longitudinal wave transport. In both cases storm waves are described as the main factor responsible of the origin and development, and both final facies are characterized by ridges of coarse sediments above the finer sediments of a tidal flat. The Odiel–Tinto estuary is one of the most significant estuarine systems of the mesotidal Huelva Coast, on the northwestern portion of the Gulf of Cadiz, and Saltés Island is a part of the closure history of the estuarine system. Previous works on Saltés Island described the surficial disposition of sandy landforms as a classic ridge chain or a barrier-island succession; nevertheless an architectural scheme based on a vibracore study shows a disposition that accord to the typical chenier plain facies model. This disagreement was the basis for a controversy about the origin of the ridges. In this study historical nautical charts and aerial photographs document the evolution of the last of these cheniers during the past 200years. In contrast to the accepted models of chenier evolution, the cheniers of Saltés Island migrated on the tidal flat but did not evolve only during storms, indeed their development occurred mainly during high spring tides. The data presented in this paper are used as the basis for a new conceptual model of chenier generation and evolution. The model consists of a migration of sand bars in a similar way to the classic beach ridges, with the difference that in our case, the bars migrate over a tidal flat. From a local point of view this paper removes the controversy about the origin of the island's geomorphology, but from a global point of view this mechanism can explain certain chenier plains in estuarine mouths located in other coasts of the world. [ABSTRACT FROM AUTHOR]

Abstract: Fluvial geomorphology seeks to study river landform history, understand formative processes, and predict changes using a combination of field observation, experimental studies and numerical models. A resurgence in fluvial geomorphology is taking place, fostered for example by its interaction with river engineering, and the availability of new analytical methods, instrumentation and techniques. These have enabled development of new applications in river management, landscape restoration, hazard studies, river history and geoarchaeology. This paper presents a perspective on recent advances in fluvial geomorphology, and introduces a selection of papers presented during the Fluvial Geomorphology and Palaeohydrology session within the Sixth International Conference on Geomorphology held in Zaragoza (Spain) in September 2005. [Copyright &y& Elsevier]

The term “incision wave” was coined in the 1990s to describe wave-like patterns of stream incision propagating through numerically modeled bedrock-channel river systems. An incision wave consists of a crest where available stream power is greatest, and where vertical incision is most rapid. The crest is flanked by limbs where there is less available stream power and where vertical incision rates are slower. Farther away from the crest, available stream power is less and incision rates are slower than in the limbs. Modeling results suggest tectonically induced base-level fall triggers incision waves that propagate upstream through bedrock-stream networks. However, it has recently been postulated that the equation underpinning incision-wave models cannot realistically simulate river systems. This paper provides field-geological evidence supporting the hypothesis that tectonically induced base-level fall triggers incision waves that propagate through bedrock-stream networks for tens of kilometers.Mid and late Pleistocene alluvial morphostratigraphy in the Rı´o Andarax drainage basin, southeast Spain is interpreted to indicate that patterns of paleo stream power were controlled by an incision wave. In the conceptual model proposed in this paper, the signature of an incision wave in the Rı´o Andarax drainage network is recorded by the contrasting morphostratigraphy of oxygen isotope stage 8 (“OIS8”) time landforms. At the crest of the incision wave during OIS8, there is no record of a paleoalluvial level because available stream power exceeded critical stream power and streams were incising vertically. The crestal area is flanked by OIS8-time strath terraces, which record the position of the two limbs of the incision wave. Farther upstream, OIS8-time alluvial fills mark an area unaffected by the incision wave.During oxygen isotope Stage 2 (“OIS2”) and/or oxygen isotope Stage 1 (“OIS1”), sediment availability in the Rı´o Andarax catchment was low, and the pattern of relative stream power was threshold-like rather than wave-like. Differences in the manifestation of the incision wave during OIS8 vs. during OIS2 and/or OIS1 indicate that climate and sediment availability can control how incision waves propagate through fluvial systems. [Copyright &y& Elsevier]

Gully erosion represents one of the most significant types of land degradation in the Mediterranean areas, giving place to important on- and off-site effects. In this paper, a second-order gully located in SW Spain is analyzed. Along the gully, 28 cross-sections were established and measured with a Leica TCRM1102 laser total station, approximately every 6 months from 2001 to 2007. The sections were located at variable distance, placing them in areas where active erosion was evident. In total, 13 field measurements were carried out, and the geometric characteristics of 28 cross-sections were obtained. Morphometric analyses were carried out in both the main gully and a tributary reach by applying an empirical relationship between channel length and eroded volume. Morphometric variables of the gully sections were combined into two dimensionless groups, and a morphological similarity between different linear erosion landforms (rills, ephemeral and permanent gullies) was obtained. Then, the coefficient of variation of the calculated volumes was used to compare the instability between the main gully and the tributary reach. Finally, the hydraulic geometry of the gully was assessed by calibrating three empirical power equations, which relate bankfull discharge with mean flow velocity, cross-sectional depth and width. The hydraulic characterization of the main gully and the tributary reach was investigated for each field survey and a different behavior was detected. The hydraulic analysis also demonstrated that higher values of discharge provide better predictions of flow velocity; the size of the main and tributary gullies affects the discharge–width relationship; and that gully depth is the variable which can be predicted with the highest accuracy. [ABSTRACT FROM AUTHOR]

Abstract: This special issue of Geomorphology consists mainly of selected papers from the S15 Session: GIS and SDA applications in Geomorphology at the 6th International Conference on Geomorphology held in Zaragoza (Spain) in September 2005. For this session, 53 abstracts from Europe, Asia, the Americas, Africa and Oceania were submitted, and 18 oral communications and 35 posters were presented. The session provided an opportunity to overview, discuss and evaluate new advances of GIS (Geographical Information Systems) and SDA (Spatial Data Analysis) applications in the field of geomorphology. Eight of the manuscripts submitted for the publication call for this special issue survived the review process, and two other invited contributions together form this special issue with 10 papers. [Copyright &y& Elsevier]

Dolines, or closed karst depressions, are the most characteristic feature of karst landscapes. The two main types of doline are those formed by the removal of material by solution and those formed by the geological processes of collapse or suffosion. Solution dolines are most frequently found in carbonate karst in high relief karst massifs. Various algorithms can be used to identify and delineate dolines in high-resolution digital elevation models (DEM) where the lower size limit is determined by the resolution of the DEM, i.e., the size of the cell or the DEM pixel in terrain units. The work presented here addresses the size distribution of dolines, which is a significant component of the geomorphometric analysis of dolines. On the basis of experimental results, various authors have advocated the lognormal or the power distribution as the best fit to experimental data. A power distribution is consistent with a fractal structure implying the fractal nature of the sizes of dolines which, in turn, may reflect a relationship between size and the structural controls of fracture networks and the fractal fragmentation of the terrain. This paper presents case studies of four karst landscapes that are representative of karst massifs in Spain. Two of these are located in the Pyrenees in the north of Spain and two are located in the Betic mountains in the south of Spain. In all four cases, a lognormal distribution provides a bad fit while a power law distribution provides a good fit in three cases and in the fourth case provides a good fit for dolines that have a diameter greater than 50 m. • The paper presents an analysis of the size-distribution of dolines in four high relief karsts. • In the four cases studied, the lognormal distribution does not fit the experimental data. • In three of the four cases, the power law provides a good fit to the data. • In the remaining case the power law is a good model for dolines larger than 50 m. • The power law implies the fractal character of the sizes of dolines. [ABSTRACT FROM AUTHOR]

This paper evaluates the predictive power of nine bedload equations, comparing the results provided by the equations with the bedload rates obtained in a previous field-based tracer experiment accomplished in River Pigüeña and River Coto, two coarse bed streams from NW Spain. Rivers from NW Spain draining the northern watershed of the Cantabrian Mountain range flow into the Bay of Biscay in a short path (50–60 km). In this region, they are developed forested catchments featured by fluvial networks with relatively steep slopes, single-thread sinuous channels, and where bed sediment is typically coarse (cobble and gravel). Tagged stones were used to trace bed sediment movement during flood events in River Pigüeña and River Coto, the two main tributaries of the Narcea River basin. With the tracer results, bedload transport rates between 0.2 and 4.0 kg/s were estimated for six flood episodes. The tracer-based bedload discharges were compared with the bedload rates estimated with the bedload formulae (DuBoys–Straub, Schoklitsch, Meyer Peter–Müller, Bagbold, Einstein, Parker–Klingeman–McLean, Parker–Klingeman, Parker and Wilcock-Crowe). Our assessment shows that all of the bedload equations tend to overestimate when compared with the tracer-based results, with the Wilcock and Crowe (2003) equation the only exception in River Pigüeña. We linked these results to the particular geomorphology of coarse-bed rivers in humid and forested mountain environments. Within these rivers, armored textures and structural arrangements in the bed are ubiquitous; these features, together with a low sediment supply coming from upstream forested reaches, define a supply-limited condition for these channels limiting the potential use of bedload equations. The Wilcock and Crowe (2003) equation introduces complex corrections into the ‘hiding function’, and this could explain why it performs better. [ABSTRACT FROM AUTHOR]

Abstract: This paper reviews the sedimentological and geomorphological imprints of prehistoric and historical tsunamis in the four main estuaries of SW Spain. These imprints include beach erosion, filling of intertidal channels, deposition of bioclastic layers, washover fans and reworked aeolian sheets and the breaching of spits and tombolos. Most of these imprints were caused by the 218–209BC and AD1755 tsunamis, although evidence of other tsunamis has been identified. In these two events, effects on human populations were severe and diverse, such as human loss of life, changes in coastal settlements and international borders, damage to port infrastructure or flooding of marsh and inhabited areas. New radiocarbon reservoir data were included in order to obtain an approach to the recurrence period of these high-energy events (700–1000years) in this area. [Copyright &y& Elsevier]

Abstract: Over the last forty years, applying dendrogeomorphology to palaeoflood analysis has improved estimates of the frequency and magnitude of past floods worldwide. This paper reviews the main results obtained by applying dendrogeomorphology to flood research in several case studies in Central Spain. These dendrogeomorphological studies focused on the following topics: (1) anatomical analysis to understand the physiological response of trees to flood damage and improve sampling efficiency; (2) compiling robust flood chronologies in ungauged mountain streams, (3) determining flow depth and estimating flood discharge using two-dimensional hydraulic modelling, and comparing them with other palaeostage indicators; (4) calibrating hydraulic model parameters (i.e. Manning roughness); and (5) implementing stochastic-based, cost–benefit analysis to select optimal mitigation measures. The progress made in these areas is presented with suggestions for further research to improve the applicability of dendrogeochronology to palaeoflood studies. Further developments will include new methods for better identification of the causes of specific types of flood damage to trees (e.g. tilted trees) or stable isotope analysis of tree rings to identify the climatic conditions associated with periods of increasing flood magnitude or frequency. [Copyright &y& Elsevier]

Abstract: Gyprock is a common rock in evaporitic formations, which have a wide distribution across all continents. However, outcrops of gyprock are rather limited, occurring mainly in low rainfall areas (i.e. southwest of USA, Italy, Spain). Gyprock is one of the most common lithology in the Ebro Tertiary Basin. Here, semiarid conditions propitiate the development of specific weathering processes and landforms with significant implications for understanding the genesis of soils and the geomorphological evolution of these areas. Gypsum crystallization within the pores and fissures of gyprock close to the surface leads to volume increase and pressures, with the consequent weathering of this rock. As a result, considerable porosity develops producing peculiar morphologies on gyprock outcrops (domes and decimetre-scale blisters), specific microscopic features (voids with plain walls, horse-shoe pores and serrated pores), as well as microscopic fabrics (grating fabric, skeletal fabric, fan fabric and botryoidal fabric). This paper presents a morphological characterization of the material forming the various types of weathering features, from microscopic to mesoscopic scale. The macromorphology and micromorphology of those features were used to interpret their genesis. [Copyright &y& Elsevier]

Abstract: Geomorphological, sedimentological and geochronological analyses have been undertaken to decipher the effects of Quaternary environmental change on the development of the Rio Bergantes, Ebro basin, northeast Spain. Field mapping and profiling using aerial photography and airborne LiDAR data have identified a sequence of six river terraces. Age control, provided by luminescence dating, has revealed two major phases of valley floor aggradation that appear to have occurred at ~183–130ka (Terrace BT1, elevated ~25m above the modern river channel) and ~111–26.8ka (BT2, ~18–20m above the modern river channel), punctuated by ~20m of incision in the intervening period. Following these two phases of large-scale aggradation, the Bergantes river system appears to have adjusted to a relatively sediment-limited regime and responded to environmental changes through a series of smaller cut and fill cycles. This resulted in four lower elevation terraces (BT3–BT6) that are inset within the older (BT1 and BT2) valley fills. These lower terraces have been temporally constrained to ~24.5–14.2ka (BT3); 10.6–9.8ka (BT4); 8.3–6.2ka (BT5) and ~3ka (BT6). Field sedimentological and stratigraphic analyses of the alluvial fills indicate the influence of tributary and hill slope derived sediment supply during the aggradation of BT1 and, to a lesser extent BT2. This contrasts with the predominantly trunk river derived deposits which make up the fill of BT3–BT6, when the hillslopes and tributaries in the study area appear to have been relatively de-coupled from the trunk river. Data presented in this paper suggest that the Bergantes river system has responded to, and has preserved, a record of environmental changes operating both in synchrony with, and at a higher frequency than, Milankovitch-driven glacial–interglacial cycles. Major net aggradation phases (those associated with relatively large amounts of fluvial sediment e.g. BT1 and BT2) appear to coincide with Pleistocene glacial conditions in MIS 6, and parts of MIS 5 and MIS 4, when the climate on the Iberian Peninsula was cool and dry. Intervening phases of net valley incision appear to coincide with warmer and moister climates in Pleistocene interglacials. The younger terraces (BT3–BT6) are characterised by much smaller amounts of fluvial sediment supply. Dating control places their development during stadial (aggradation) and interstadial (incision) events of the Late Pleistocene and Holocene. Some phases of aggradation appear to coincide with North Atlantic Heinrich Events, and also with other securely dated phases of aggradation elsewhere in the Mediterranean basin. [Copyright &y& Elsevier]

Abstract: Calas are characteristic embayed rocky coastline landforms related to steep-sided drowned valleys that were deeply incised during low sea-level stages into carbonate plateaus. This paper studies the factors that control the presence and character of calas in three different islands of the Balearic Archipelago (Mallorca, Menorca and Formentera) by means of Digital Elevation Model (DEM) reconstructions, embayment and catchment morphometric analysis and through the compilation of fault and joint orientations. All islands exhibit emerged carbonate platforms (Upper Miocene in age) characterised by horizontal or very gently-dipping bedding. Two distinct patterns observed at all study sites are the absence or poor development of calas when carbonate plateaus exhibit strong coast-parallel structures and a greater variability of cala embayment size according to stream catchment size, lithology or their catchment distance from the coastline. Furthermore, the amount of stream incision, and consequently the characteristics of a cala at its mouth, depends on the proportion of impermeable rocks exposed in each drainage basin and on the density and spacing of fractures. Karst collapse, dolines and valley infilling associated with Quaternary sea-level oscillations are also important in determining the shape and size of calas. [Copyright &y& Elsevier]

Abstract: This paper examines the greyish-blue deposits that were recently discovered in the lower levels of the Sima de la Higuera Cave (Murcia, SE Spain) which occur as patinas over the walls and ceilings, as well as coating boxwork formations. Their mineralogy was determined using XRD and micro-Raman spectroscopy, while EDX microanalysis was used to determine their elemental composition. The mineralogical analyses revealed the presence of Mn oxides (todorokite and pyrolusite) and Fe with a low degree of crystallinity, whereas EDX microprobe showed elevated concentrations of Mn (38.2wt.%), Fe (15.2wt.%) and Pb (8.1wt.%). The ferromanganese oxyhydroxides occur as botryoidal aggregates overlying blades of calcite that have a visibly sugary texture. The speleogenetic model proposed describes (1) an initial phase of precipitation of hydrothermal calcite veins (of hypogenic origin) within the fissures of the host rock under phreatic conditions and (2) a subsequent vadose phase involving preferential corrosion of the carbonate host rock caused by lowering of the pH resulting from CO2 diffusion in condensed water and oxidation of Fe and Mn under aerobic conditions, probably mediated by microorganisms. It is this later phase that gave rise to the boxwork. The boxwork of the Sima de la Higuera Cave is a singular example of a formation that is generated by dissolution–corrosion of the rock due to acidification caused by oxidation of iron and manganese. [Copyright &y& Elsevier]

Abstract: This paper presents an initial analysis of the rockfall processes affecting the walls of the canyon of the River Duratón. This 34km long meandering canyon in the basin of the River Duero in central Spain (41°18′ N, 3°45′ W) has evolved in a large-scale outcrop of Late Cretaceous calcareous rocks (dolomite and limestone) deformed into a series of asymmetrical folds. Its vertical scarps range from 80 to 100m; its width varies from 150 to 300m; and its floor is between 30 and 50m wide. The research consisted of drawing up an inventory of rockfalls from a field survey and mapping the fallen blocks deposited on the basal talus or on the canyon floor, which in turn allowed the original location of each block on the scarps to be identified and located on the orthophotos available. A Digital Elevation Model (DEM) was produced using a Geographic Information System (GIS) and maps made of the aspects and slopes. The aspect of each rockfall data point was determined, and this initial database was completed with other significant parameters (location on the valley side, relationship with the tectonic structure and relative age). An approximate delimitation was also produced of the potential rockfall source area, by reclassifying the slopes according to morphometric criteria. The result is a geomorphic rockfall inventory map, showing the distribution of the rockfalls and a basic statistical analysis to allow a preliminary evaluation of the rockfall characteristics in relation to both their topoclimatic location (aspect) and their structural location (with or counter to the dip of the strata) and to the current geomorphic dynamic through a study of recent scars on the scarps. Recent rockfalls have also been related to the meteorological conditions in which they occurred. [Copyright &y& Elsevier]

Abstract: Active tectonic deformation influencing the streams and hillslopes of the Sierra Alhamilla ridge (anticlinorium) in southeast Spain is related to the dextral-reverse Polopos Fault Zone to the north and east of the ridge and to normal faulting in the southern side of the ridge. A fault segmentation and fluvial terrace mapping is presented in this paper. The following geomorphic indices were calculated in the area: the mountain-front sinuosity, valley floor width-to-height ratio, drainage basin asymmetry factor, basin hypsometric curve and integral, longitudinal river profile and stream-length gradient index normalized by the graded river gradient (SLk index). The SLk map shows two sets of high anomalies: a) an E–W-striking anomaly, due to the dextral-reverse Polopos Fault Zone located in the northern limb of the anticlinorium; b) a group of NNW–SSE-striking anomalies, associated with Pliocene–Quaternary NW–SE- to NNW–SSE-striking high-angle normal faults that cut the southern limb. Late Pleistocene–Holocene activity occurred along the North Alhamilla Reverse Fault and the dextral transpressive South Gafarillos Fault, two segments in the Polopos Fault Zone. The former fault produces rejuvenation of the streams at the base of the northern slope. In this area, mountain-front sinuosity and valley floor width-to-height ratio suggest Quaternary uplift rates between 0.05 and 0.5mky−1. Holocene to present-day activity of the South Gafarillos Fault is demonstrated by faulted late Pleistocene terraces and Holocene colluvial deposits and suggested by deflected streams that have complex or convex hypsometric curves. Pliocene–Quaternary high-angle normal faults control the relief in the southern limb and the western end of the Sierra Alhamilla. These faults produce low mountain-front sinuosity and valley floor width-to-height ratio indices typical of uplift rates quite higher than field-based rates from some other studies. [Copyright &y& Elsevier]

Abstract: Rock coatings are frequent on natural rock outcrops and even more on stone surfaces of historical buildings and monuments. They are interesting as some of them have a protective effect against erosion. In the last 30years, research on rock coatings has been performed separately on either buildings or natural outcrops. This paper studies and compares thin coatings found on granitic rock surfaces of historical buildings with coatings found on natural granite outcrops in a same climatic area (NW Spain) by analysing their surface and cross-sections. As rock surfaces of buildings have known age they can be used to assess rates of weathering and coating growth. This is the first comparative study of formation of coatings on natural and built surfaces in the same region. Both endogenous (rock characteristics) and exogenous factors (climatic conditions, air pollution) that could affect the coatings formation are considered to assess the origin and formation of coatings. X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analyses of the underlying rocks, XRD analyses of the coatings and Scanning Electron Microscopy (SEM) observations of surface and cross-sections of the coatings, performing Energy Dispersive Spectrometry (EDS) and X-ray maps, were carried out to establish their composition. Fieldwork and results indicate that natural outcrops are widely covered by biological coatings or coatings formed due to rock weathering, while coatings found on rock ashlars are highly variable with air pollution, other building materials, organic droppings and micro-environmental factors contributing to coatings on rock ashlars in a more significant way than substrate characteristics and exposure time. [Copyright &y& Elsevier]

Abstract: The northern slope of the Sierra de Aitana (Eastern Betic Cordillera) is characterized by a long mountain front with a prominent Eocene limestone scarp overlying ductile Eocene marlstones. This stratigraphic feature and the highly stepped topography produced by several normal faults favor gravitational processes such as rock avalanches, rock slides and rock falls. This paper reports a compound landslide comprising a rotational rock slide and slab-type lateral spreading affecting these materials with blocks of volumes up to 106 m3. This lateral spread process produced singular and spectacular morphological features, the Simas de Partagat, which are trenches 20m wide and up to 40m deep, formed by the widening of discontinuities. The use of a differential SAR interferometry technique for monitoring this landslide over a time span of 11yr has revealed that velocity of movement is insignificant, with rates comprised between 0 and 2mmyr−1 and cumulative negligible displacements. Individual rock blocks initially located at the free face of the scarp were affected by slides at the base of the scarp, descending from a few to several dozen meters along the slope. Blocks broke up as displacement progresses, with several in different stages of evolution being recognizable along the slope. Differential SAR interferometry shows a greater activity in the area north of compound landslide, although velocity is extremely low (below 16mmyr−1). This extremely slow movement revealed by interferometry is in agreement with other geological and geomorphological evidence such as the existence of speleothems and cemented breccias against the head walls of the trenches. Both deposits are indicative of a long period of discontinuity widening. Also, undisturbed debris deposits covering ancient rock slides are indicative of very slow gravitational processes characterized by long dormant periods. In addition, a historical picture from 1898 shows nearly negligible change in the Simas de Partagat over this 112yr period. [Copyright &y& Elsevier]

Abstract: Coastal lagoons are valuable water bodies since they are of great ecological and economic interest throughout the world. Their existence is controlled by variations in sea level and the geological substrate of their location. Their morphology is linked to local topography, alternation of high and low pressure, the presence of a river, as well as tidal regime. All these factors influence lagoons along the coastline in the south of Spain. The main morphological characteristics of such lagoons are the following: intermittence, one-dimensional morphology, small size, shallow waters, high area/depth ratio, no flood- or ebb tide deltas, overwash of their low barriers during storms, high evaporation rates and feeding by rivers. Effective management of these systems requires the evaluation not only of their hydrodynamics and opening and closure rate, but also the prediction of possible future scenarios as a response to meteorological events. This paper describes the behavior of a coastal lagoon in Zahara de los Atunes (Cádiz) by means of a numerical model implemented with the objective of serving as a tool for optimizing the coastal zone management. Although the coastal lagoon at Zahara de los Atunes is closed most of the year, it is artificially opened at the beginning of the summer. The results of our study showed that during this period, the lagoon is flood-dominated with a pumping-mode response. It naturally tends to close since it is a trap for littoral drift sediments. The precise date of closure depends on the events that take place during the autumn, which determine whether the sediments deposited in the inlet by the littoral drift are flushed out by the river flow or flushed in by the waves. [Copyright &y& Elsevier]

Abstract: Although gully erosion is generally considered a major process of land degradation, its contribution to total soil loss by erosion has recently been a subject of much discussion. The lack of adequate methods for the documentation and monitoring of gullies resulted in the shortage of quantitative data. Therefore, a high-resolution remote sensing system for aerial surveys by blimp or kite has been developed which meets spatial and temporal image resolutions required for short-term gully monitoring. The objective of this paper is to examine the potential of a method using non-metric digital photogrammetry and GIS for gully surface modelling and monitoring. Two bank gullies representing different morphological types of gullies (V-shaped and U-shaped) were chosen from a dataset of gully systems in semi-arid Spain. The considerable relief energy and complex topography of the gullies in a natural, vegetated landscape were found to be a challenge to digital photogrammetric techniques, introducing errors which inhibit fully automated DEM generation. Using a hybrid method combining stereomatching for mass-point extraction with manual 3D editing and digitizing, high-resolution DEMs (5 and 7.5 cm pixel size) were created for the study sites. GIS analysis of the DEMs for different monitoring periods (2 to 4 years) allowed the computation of gully area and volume, as well as their changes with an accuracy and detail sufficient to represent the geomorphological forms and processes involved. Furthermore, the spatially continuous survey of the entire form offered the possibility of distinguishing different zones of activity both at the gully rim and within the gully interior, identifying patterns of erosion and deposition which indicate the limited use of headcut retreat rates for the assessment of sediment production on a short-term basis. [Copyright &y& Elsevier]

Abstract: Digital elevation models (DEMs) can be useful tools to assess morphologically and hydrologically active processes. This paper presents a method to obtain accurate DEMs, an analysis of DEM errors and the benefits of GIS techniques for mapping geomorphological features and active processes in the karstic endorheic catchment with three permanent lakes (Estaña lakes) in the External Ranges of the Spanish Pyrenees. Field work revealed the lack of accuracy in the original DEM. A method was then proposed to obtain a hydrologically correct DEM using a Total Topographic Station (TTS) and a Global Positioning System (GPS). On a regular grid, 246 topographic points were recorded with a GPS and 237 points were measured with a TTS on areas of gentle slope. The mean and standard deviation of the error of the corrected DEM were −1.5 and 3.2 m, respectively. By using a combined flow algorithm, a flow accumulation map was derived from the corrected DEM and the study area was divided into fifteen sub-catchments. The values of the indices of watershed circularity and elongation have a strong variation and the map of flow length also showed strong asymmetry. Maps of land use, topography and lithology were created in order to establish the basis for mapping main geomorphological features. The new DEM also provided a basis for calculating the topography factor (LS) in RUSLE, an empirical soil erosion model. A map showing the error of the original DEM indicates that the highest error values occur in the main karstic features of the geomorphological map. Hence, the proposed methodology including DEM correction is useful for an accurate assessment of topographical and geomorphological features in karstic environments. [Copyright &y& Elsevier]

Abstract: This paper discusses the use of 222Rn concentrations in water of natural springs as a geomorphological method to identify latent faults in low-mid term activity areas. The identification of this type of active fault may be crucial in hazard analysis, structural geomorphology and in landscape evolution analysis. The test used to identify these faults is based on the measuring of 222Rn concentrations in water of springs linked to faults, and comparison with those obtained from springs which, although exactly the same lithological context, are not linked with faults (reference values). If the difference between the measured value and the reference value is positive then an anomaly is identified and that measurement indicates a spring linked to a latent fault. The test was applied and validated in springs linked to faults with a latent behaviour in Cantabria, Northern Spain. These faults have shown an intermittent movement over the last 50,000 years, and have contributed towards landslide processes playing a significant role in landscape evolution of the area. [Copyright &y& Elsevier]

Abstract: This paper presents an analysis of the dune field dynamics of El Fangar Spit in the Ebro Delta (Spain), associating it with the internal structure of dunes carried out with ground-penetrating radar and supported by data from topographic DGPS. These analyses are of great importance to ascertain the state of the internal structure of dunes as an important element in their stability and, therefore in their evolution. The internal structure shows accretion and progradation sequences of dunes over beach deposits, which depend on dune morphology (height, crest orientation) and location, as well as the processes acting on them. [Copyright &y& Elsevier]

Hydrological and geomorphological impacts upstream dams have been less frequently investigated than those occurring downstream. Geomorphological mapping, multitemporal analysis of aerial photos, topographic survey comparison of the channel bed, and archives of information concerning flood events were used in this paper to document the effects that occurred upstream of the Cantillana Dam along the lower Guadalquivir River. The results show that the construction of the dam in 1956 caused progressive siltation that reduced either the water surface width (36.5% until 2010) or the reservoir volume (70% reduction until 2012). These changes decrease from the upstream boundary of the reservoir to the dam but show an increase in correspondence with the main tributary (Rivera de Huéznar) in the middle part. The aggradational process along the reservoir reach caused a reduction in the channel cross-sectional area and its flow capacity during floods. Consequently, higher river stages are reached for the same flow discharge, thereby producing an increased frequency and duration of inundation of the alluvial terraces adjacent to the reservoir. • Siltation upstream the Cantillana Dam along the Guadalquivir River caused a reduction of water surface width and reservoir volume. • Frequency and duration of inundation of the alluvial terraces increased for discharges 20–30% lower than pre-dam. • A conceptual channel evolution model upstream the dam is proposed. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyses the factors which influence the presence or absence of tributary-junction fans in the Iberian Range, northern Spain. Two valleys were selected, both characterised by wide variations in lithology, altitude, land use and plant cover. Two groups of factors were studied: those related to the internal characteristics of the drainage basins, which particularly control sediment generation; and those related to the characteristics of the depositional area which control accommodation space and main river power. Among the internal factors, the development of alluvial fans was related to: (i) the capacity of the basin to yield large volumes of sediment, (ii) the occurrence of intense human pressure until recent times, a good indicator of sediment yield, and (iii) the capacity of the basin to quickly increase discharge during rainstorms (discharge density and torrentiality). It is suggested that the areas that were intensively cultivated in the past, and have therefore been affected by intense erosion, have played a decisive role on the development of alluvial fans. This would imply that many of these alluvial fans have a relatively recent origin, perhaps related to the beginning of a widespread deforestation. The basins without alluvial fans are characterised by relatively steep hillslope gradients (that is, slopes that never were subjected to historical cultivation), low drainage densities and dense forest and shrub cover, mostly coinciding with high altitude basins composed of quartzite and shale bedrocks. Regarding the external factors, the shape, size and longitudinal gradient of the main river to which the fans are tributary are the most relevant conditioning factors determining the development of alluvial fans. [Copyright &y& Elsevier]

Abstract: The Arroyo de Gor is a highly incised stream (up to 200 m) that has eroded into the Pliocene–Pleistocene infill of the Guadix basin in the Betic cordillera (SE Spain). This paper concentrates on a particular reach of this stream, namely the Cenascuras–Gorafe reach, where abundant inactive rotational slides can be recognized on both hillslopes of the canyon-shaped valley. The rotational slides have surface areas of 5–15 ha and volumes of mobilized material of 5–15 Hm3. These rotational slides can be recognized by their main scarps, which are still well featured at both margins of the valley, as well as by the counter hillslope rotation of the strata in their bodies. The surfaces of rupture are concave, their width being greater than their length, i.e. the landslides are elongated in a direction perpendicular to the landsliding displacement and parallel to the stream. At depth, the surfaces of rupture developed on fine-grained sediments (mostly clays) underlying the conglomerates and sands affected by the rotational slides. The clays at the surface of rupture are smectite-rich and show several features produced by the landsliding, such as striations and sigmoidal-shaped structures. The Cenascuras–Gorafe canyon has been developed by a combination of entrenchment, fracturing and landsliding. Initial deep entrenchment of the stream is attributed to a base-level lowering related to the capture of the former endorheic basin by the Gualdalquivir river in the late Pleistocene. This river incision created a canyon with subvertical unstable walls, which due to gravitational instability would give way to vertical open tension cracks some distance from the canyon edge. The tension cracks would end at depths equal to the base of the canyon, which also coincides with the contact between the conglomerates and the underlying clays. The rotational slides are thought to have occurred during heavy rains by a combination of piping, which would have lengthened the tension cracks, and infiltration, which would reduce the shear strength along the gently dipping contact between conglomerates and the underlying clays. Thus, the blocks bounded by the tension cracks and the subhorizontal lithological contact would slide under their own weight on the subhorizontal surfaces of reduced shear strength. Several age constraints lead us to tentatively assign the landslides to the Isotope stage 5 (around 32 ka), an interglacial period agreed to be wetter and slightly warmer than the present-day semi-arid climate. [Copyright &y& Elsevier]