Lecanora rhizinata spec. nova, liquen taxonómicamente aislado, sobre fisuras de rocas exfoliables, en España

Se describe una nueva especie de Lecanora Ach. (L. rhizinata Poetl., Barreno & Rico) de la alta montaña del Centro de España, que se desarrolla sobre rocas metamórficas fácilmente exfoliables. La especie puede encuadrarse dentro de la subsección Concolores Poelt (sect. Petrasterion Poelt, subgen. Placodium (Pers.) Poelt) del género Lecanora. Sin embargo, la compleja estructura anatómica del talo, en la que se diferencian fascículos de hifas fuertemente conglutinadas, que partiendo del córtex penetran hacia la médula llegando, en ocasiones, hasta el límite inferior de la escuámula e intercalándose con la capa gonidial a la que disgregan en glomérulos, unido a la presencia de cordones rizinales («Rhizinenstränge»), hacen que la nueva especie tenga una posición aislada dentro del grupo Concolores y pudiera reclamar un estatus distinto. Asimismo se hace una comparación con otras especies de la citada subsect. Concolores y con otros géneros de Lecanoraceae.

Floristic notes of Sierra del Rincón Biosphere Reserve (Spain, Madrid province)

New records of vascular plants from Sierra del Rincón Biosphere Reserve and surroundings (Spain, Madrid province) are provided. It is noteworthy the presence of atlantic flora in this continental area and the different shrubby communities in different sectors with different litology: in areas with gneiss they are dominated by leguminous genisteae; where it is schistous, shale or quartzite they are heathlands.

Líquenes silicícolas de zonas húmedas, Puentedeume (La Coruña)

Se citan 13 especies de liquenes saxícolas de rocas ácidas, de 12 de ellas no hemos encontrado citas anteriores para España.

Líquenes silicícolas de la Sierra del Relumbrar (Oeste de Albacete, España)

Resultados florísticos de la exploración del extremo oriental de Sierra Morena, de rocas ácidas y duras (cuarcitas y pizarras). Se da cuenta del hallazgo de 105 especies, en su mayor parte mediterráneas, aunque con la ausencia de las especies termófilas de las zonas bajas del SE. Se ofrece la descripción de algunas especies que no ha sido posible identificar, así como la de otras especies poco conocidas o escasamente citadas. Destaquemos entre ellas las incluidas en el resumen en inglés.

Notas briológicas valencianas

En esta nota se estudian la ecología y corologia en España de tres especies de musgos nuevas para el Levante español. Una de ellas, Atrichum undulatum (Hedw.) P. Beauv., abundante en las montañas de la península pobres en bases, con rocas del tipo: areniscas, silíceas, granitos, etc. De las otras dos especies, Neckera besseri (Lob.) Jur. y Dichodontium pellucidum (Hedw.) Schimp. var. propagulifera (Corr.) Cas. Gil, se aportan nuevas localidades, ampliando así su área de distribución hacia el sur.

Validations and descriptions of European syntaxa of vegetation dominated by lichens, bryophytes and algae

Fourty-two high-rank syntaxa and seven associations of the thallophyte system of syntaxa are either described as new or validated in this paper. Among those, there are the following nine classes: Aspicilietea candidae, Caulerpetea racemosae, Desmococcetea olivacei, Entophysalidetea deustae, Gloeocapsetea sanguineae, Mesotaenietea berggrenii, Naviculetea gregariae, Porpidietea zeoroidis, Roccelletea phycopsis. Eleven orders and ten alliances as well as three associations are described or validated: the Aspicilietalia verruculosae (incl. Aspicilion mashiginensis and Teloschistion contortuplicati), the Caulerpetalia racemosae (incl. Caulerpion racemosae), the Desmococcetalia olivacei (incl. Desmococcion olivacei), the Dirinetalia massiliensis, the Fucetalia vesiculosi (incl. Ascophyllion nodosi), the Gloeocapsetalia sanguineae, the Lecideetalia confluescentis (incl. Lecideion confluescentis), the Mesotaenietalia berggrenii (incl. Mesotaenion berggrenii, Mesotaenietum berggrenii and Chloromonadetum nivalis), the Naviculetalia gregariae (incl. Oscillatorion limosae and Oscillatorietum limosae), the Porpidietalia zeoroidis (incl. Porpidion zeoroidis), and the Roccelletalia fuciformis (incl. Paralecanographion grumulosae). Further, five orders, seven alliances and four associations, classified in known classes, were described as well. These include: the Bacidinetalia phacodis, the Agonimion octosporae and the Dendrographetalia decolorantis (all in the Arthonio radiatae-Lecidelletea elaeochromae), the Staurothelion solventis (in the Aspicilietea lacustris), the Pediastro duplicis-Scenedesmion quadricaudae and the Pediastro duplicis-Scenedesmetum quadricaudae (both in the Asterionelletea formosae), the Peccanion coralloidis and the Peltuletalia euplocae (both in the Collematetea cristati), the Laminarion hyperboreae, the Saccorhizo polyschidi-Laminarietum and the Alario esculenti-Himanthalietum elongatae (all in the Cystoseiretea crinitae), the Delesserietalia sanguinei, the Delesserion sanguinei and the Delesserietum sanguineae (all in the Lithophylletea soluti), as well as the the Rinodino confragosae-Rusavskietalia elegantis and the Rhizocarpo geographici-Rusavskion elegantis (both in the Rhizocarpetea geographici).

Control estructural de agrietamientos poligonales en la Pedriza del Manzanares (Madrid)

Los agrietamientos poligonales representan una forma común de modelado granítico cuyo origen y evolución continúa en fase de estudio, no existiendo una sistematización de estas estructuras diversas. Algunos autores explican su origen por procesos geodinámicos internos, relacionándolo con movimientos de planos de fractura en estados tardíos de consolidación magmática. Otros autores atribuyen su formación y desarrollo a factores externos relacionados con el régimen climático. La gran variedad de agrietamientos poligonales requiere la utilización de un número mayor de variables para definir los distintos orígenes, y las posibles interrelaciones entre los factores externos e internos, así como para explicar la evolución de dichas estructuras y avanzar en la clasificación de los patrones concretos. Este trabajo pretende contribuir a sistematizar los mecanismos que intervienen en el desarrollo de agrietamientos poligonales. Para ello se estudian únicamente agrietamientos poligonales formados sobre planos de fractura verticales o subverticales. En particular se establecen relaciones entre la presencia de agrietamientos poligonales y la red de fracturación, la altura de aparición, la orientación e inclinación de la pared, la morfología de las placas y la profundidad de incisión de las grietas perimetrales. Por otra parte, establece relaciones entre procesos geodinámicos internos y procesos de meteorización externos.

The Pico de Navas slump (Burgos, Spain): a large rocky landslide caused by underlying clayey sand fluidification

The Pico de Navas landslide was a large-magnitude rotational movement, affecting 50x106m3 of hard to soft rocks. The objectives of this study were: (1) to characterize the landslide in terms of geology, geomorphological features and geotechnical parameters; and (2) to obtain an adequate geomechanical model to comprehensively explain its rupture, considering topographic, hydro-geological and geomechanical conditions. The rupture surface crossed, from top to bottom: (a) more than 200 m of limestone and clay units of the Upper Cretaceous, affected by faults; and (b) the Albian unit of Utrillas facies composed of silty sand with clay (Kaolinite) of the Lower Cretaceous. This sand played an important role in the basal failure of the slide due to the influence of fine particles (silt and clay), which comprised on average more than 70% of the sand, and the high content presence of kaolinite (>40%) in some beds. Its geotechnical parameters are: unit weight (δ) = 19-23 KN/m3; friction angle (φ) = 13º-38º and cohesion (c) = 10-48 KN/m2. Its microstructure consists of accumulations of kaolinite crystals stuck to terrigenous grains, making clayey peds. We hypothesize that the presence of these aggregates was the internal cause of fluidification of this layer once wet. Besides the faulted structure of the massif, other conditioning factors of the movement were: the large load of the upper limestone layers; high water table levels; high water pore pressure; and the loss of strength due to wet conditions. The 3D simulation of the stability conditions concurs with our hypothesis. The landslide occurred in the Recent or Middle Holocene, certainly before at least 500 BC and possibly during a wet climate period. Today, it appears to be inactive. This study helps to understand the frequent slope instabilities all along the Iberian Range when facies Utrillas is present.

Gravity collapse structures in the Central Precordillera fold-andthrust belt, Argentina

Several landforms found in the fold-and-thrust belt area of Central Precordillera, Pre-Andes of Argentina, which were often associated with tectonic efforts, are in fact related to non-tectonic processes or gravitational superficial structures. These second-order structures, interpreted as gravitational collapse structures, have developed in the western flank of sierras de La Dehesa and Talacasto. These include rock-slides, rock falls, wrinkle folds, slip sheets and flaps, among others; which together constitute a monoclinal fold dipping between 30º and 60º to the west. Gravity collapse structures are parallel to the regional strike of the Sierra de la Dehesa and are placed in Ordovician limestones and dolomites. Their sloping towards the west, the presence of bed planes, fractures and joints; and the lithology (limestone interbedded with incompetent argillaceous banks) would have favored their occurrence. Movement of the detached structures has been controlled by lithology characteristics, as well as by bedding and joints. Detachment and initial transport of gravity collapse structures and rockslides in the western flank of the Sierra de la Dehesa were tightly controlled by three structural elements: 1) sliding surfaces developed on parallel bedded strata when dipping >30° in the slope direction; 2) Joint’s sets constitute lateral and transverse traction cracks which release extensional stresses and 3) Discontinuities fragmenting sliding surfaces.  Some other factors that could be characterized as local (lithology, structure and topography) and as regional (high seismic activity and possibly wetter conditions during the postglacial period) were determining in favoring the steady loss of the western mountain side in the easternmost foothills of Central Precordillera.

Forest typology of broadleaf forests from Sierra Maestra, Eastern Cuba

A phytosociological study of the forests from Sierra Maestra is conducted, following the methodology of the Zurich- Montpelier School. They are transformed into a forest typology using the standards of the Institute of Agro-Forestry Research. In general, 35 types and/or subtypes are presented. From this group, the most abundant ones belong to semi-deciduous microphyll forest, followed by those from mangroves and mountain rainforest, respectively. Silvicultural treatments are needed; among them, the protection forests are those found above 800 m asl and mangroves. 

Source Provenance of Pre-Historic Granitic Grindstones: The Case Study of the Cogotas I Archaeological Site of Arroyo Mucientes/San Lázaro (Castronuño, Valladolid) and a Proposal on the General Methodological Flow Process

The occurrence of hand grindstones at the Cogotas I archaeological sites is considered to be a common feature. Given that a distant-provenance raw material is frequently involved, determination of its source is a basic factor in the search for a better understanding of resource management and for any Political Economy approach. To progress in these directions an overall study should be planned, using selected grindstones with a view to covering diverse sub-zones of the Cogotas I dispersal area, especially because of its considerable distance from the granite basement source. Such a study may today includes diverse analytical procedures combining successive geographic, petrographic, mineralogical and geochemical criteria. To check the plausibility of the proposed methodology, a preliminary test has been carried out on two granite grindstones, obtained at the archaeological excavation at the Castronuño (Valladolid) Cogotian site, which is fifty km away from an inferred source area that was presumably located at Peñausende (Zamora). The result obtained validates the proposed operational process, yielding a generalizable knowledge to other similar situations.