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Mining activity introduces severe changes in landscapes and, subsequently, in land uses. One of the most singular changes is the existence of pit lakes, which occur in active and, more frequently, abandoned mines. Pit lakes are produced by water table interception when open-pit mines deepen. Their characteristics are highly variable, depending on the type of mine, the environment or the climate. In León province there is a long tradition of coal mining that dates back to the nineteenth century, and hundreds of open pits from the 1970s to 2018 have been opened, producing permanent landscape changes. This work analyses the main parameters, including morphological measurements, depth and pH values obtained from aerial photos and field work, of 76 coal pit lakes more than 30 m in length. The vast majority of these pit lakes were unknown until now and were not included in inventories or maps. The data obtained provide baseline knowledge that will allow, in the future, potential uses (storage of water for various uses, recreational use, wildlife habitat, and geological heritage sites) for these pit lakes and establish their importance as a new geoecological environment.

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<p>Over the last few decades, environmental changes have occurred in the Cantabrian Mountains (Northwest Spain) as a result of economic, social and climatic transformations. The depopulation in the rural environment with the transformation of traditional land uses, the closure of coal mining operations, and the increase in temperatures have modified the geometry of channels, water flow, and sediment connectivity of mountain rivers.</p><p>The runoff and the sediment load are modified, and the reservoirs located downstream collect all these changes thanks to the gauging stations for water flow, up and down the reservoir and the sediment sequences inside the reservoir. Studies have been carried out in natural cuts of several reservoirs during their dry season with the aim of knowing in detail the effects of each environmental change. The studied variables are accumulation rhythms, exceptional events, granulometry, and some chemical patterns. Data have already been published in the Pisuerga River basin (Palencia) from the analysis of the sediments retained in the La Requejada Reservoir (Pisabarro et al., 2019) but are not still published in Tuerto River basin in the Villameca Reservoir (León) and in Ibias River in the Grandas de Salime Reservoir (Lugo-Asturias).</p><p>In the first one, it was found a clear tendency to reduce the grain size since 80’s, when the land use change from crops and grasslands towards rewilding were increased. This process was aid with a decrease of runoff close to 20% between 60’s to 2010’s. In the other two reservoirs, the Villameca and the Grandas de Salime, there are interesting sediment outcrops too, in the last one affected by mining activity. Samples of sediment have been taken which also show the tendency to a smaller grain-size particle in the sediments’ upper levels. In the Villameca Reservoir at consequence of a clear reduction of the extreme events in the last decades.</p><p>Significant differences in sediment thickness have been observed between northern and southern slopes of the Cantabrian Mountains partly due to the marked asymmetry slopes, proper of this mountain range. In the first (the Grandas de Salime) up to 5.5 m has been found form since 1953 (2021), but in the La Requejada and Villameca reservoirs (in the Southern slope) only 1-2 m since 1940 (2016) and 1947 (2021). During the next dry season of the reservoirs, the research will be extended to other reservoirs with the main goal of extending this analysis and understanding the Global Change implications in the connectivity and the fluvial dynamics.</p><p> </p><p><em>Pisabarro, A., Pellitero, R., Serrano, E., Lopez-Moreno, J.I. (2019) Impacts of land abandonment and climate variability on runoff generation and sediment transport in the Pisuerga headwaters (Cantabrian Mountains, Spain), Geografiska Annaler: Series A, Physical Geography, 101:3, 211-224, DOI: 10.1080/04353676.2019.1591042</em></p><p> </p><p> </p>

<p>The Schmidt-hammer has been used in Geomorphology for the last decades. The effectiveness of the method has been proven by several authors, but some limitations also exists. In this work, this procedure has been tested in glacial and periglacial landforms in five different massifs in the province of León (northwestern Spain): Vizcodillo, Arcos del Agua, Muxivén, San Isidro and Peña Pieta. Tested landforms include moraines, rock glaciers, polished outcrops, talus slopes, blockfields and a debris avalanche. Quartzite has been widely used for this purpose, but granodiorite, shales and sandstones have also been tested. Results show that Schmidt-hammer data generally agree with geomorphological reconstructions. They also show strong correlation with cosmic-ray exposure ages where they exist. Rebound values are high, ranging from ≈70-72 in the oldest landforms (last glacial stage) to ≈77-80 in the most recent ones, with small differences within massifs.<br>In Vizcodillo, four glacial stages have been clearly differentiated since the last local glacial maximum. In Arcos del Agua, periglacial deposits show two different stages of rock glaciers generation and a progressively younger age for different talus slopes related to deglaciation. At both sites, the blockfields are younger than rock glaciers. In Muxivén, Schmidt-hammer data agree with the cosmic-ray exposure dating results, indicating that most of the postglacial deposits were generated due to rapid deglaciation during the Bølling-Allerød period. In San Isidro, the results show two possible stages for rock glaciers. In Peña Prieta, different glacial and periglacial deposits were tested, but poor results were obtained.<br>Relevant differences have been observed depending on the lithology. The mean coefficient of variation in the rebound values of the boulders was 3.1% in Arcos del Agua (quartzite), 3.5% in Vizcodillo (quartzite), 3.8% in Muxivén (quartzite), 4.7% in San Isidro (quartzite sandstones), but 9.9% in Peña Prieta (granodiorite). The differences between boulders of the same landform were also clearly greater in Peña Prieta than in the other massifs, with the quarzitic areas showing the most robust results. Although it has been used in previous works with good results, in this study granodiorite presented a significant dispersion in the rebound values of the boulders, due to the fact that its internal composition is coarse-grained and presents grains with different resistance. Shales could not be correctly tested because they offered great dispersion in the data. The results addressed the importance of selecting suitable and comparable areas on boulder surfaces for Schmidt-hammer impacts, with resistant and homogeneous lithology showing better results. Conversely, areas with high lithological heterogeneity or coarse-grained boulders may not to be suitable for the Schmidt-hammer method. Further surface exposure dating is needed to establish a calibration curve in this area.</p>