Recent work has shown that surface-to-bed drainage systems re-form annually on parts of the Greenland ice sheet and some High Arctic glaciers, leading to speed-up events soon after the onset of summer melt. Surface observations and geophysical data indicate that such systems form by hydrologically driven fracture propagation (herein referred to as ‘hydrofracturing’), although little is known about their characteristics. Using speleological techniques, we have explored and surveyed englacial drainage systems formed by hydrofracturing in glaciers in Svalbard, Nepal and Alaska. In Hansbreen, Svalbard, vertical shafts were followed through ∼60 m of cold ice and ∼10 m of temperate basal ice to a subglacial conduit. Deep hydrofracturing occurred at this site due to a combination of extensional ice flow and abundant surface meltwater at a glacier confluence. The englacial drainage systems in Khumbu Glacier, Nepal, and Matanuska Glacier, Alaska, USA, formed in areas of longitudinal compression and transverse extension and consist of vertical slots that plunge down-glacier at angles of 55° or less. The occurrence of englacial drainages initiated by hydrofracturing in diverse glaciological regimes suggests that it is a very widespread process, and that surface-to-bed drainage can occur wherever high meltwater supply coincides with ice subjected to sufficiently large tensile stresses.

No abstract

The laser scanning technology offers quite new possibilities in the field of the existing monitoring of engineering structures. The basic advantage of the laser scanning technology is huge amount of measuring observations and practically complete geometric and spectral information about the measured structures, which may be required within the short time. In the context of detection of threatens related to deformations and displacements of building structures, the surface - quasi-continuous distribution of measuring points is one of the most important factors. which ensure the possibility to perform correct evaluation of safety conditions of investigated structures. The proposed technological solution offers a series of new possibilities and the resulting methodology of determination of deformations and displacements of various structures, will considerably increase the scope of possible works and analyses. This will also create the new segment of data, which will result in delivery of additional information concerning conditions of the structure to experts from various fields, such as, among others, civil engineering, construction or geotechnique, who monitor the given structure.

In the late fall of 1986, a team of cavers from the Gruppo Speleologico Marchigiano of Ancona reported to the regional Archeological Superintendence their discovery in a room of the Grotta del Fiume Cave (Marche region of central Italy) of archeological finds such as the charcoal remains of a bonfire, a number of ibex bones, and four chert artifacts. However, since the discovery and archival of all this material, no further research or focused studies were carried out about this important archeological site. Therefore, we engaged in a thorough re-examination of this site by mapping this part of the Grotta del Fiume Cave with modern surveying approaches, including terrestrial laser scanner and ground penetrating radar. Moreover, we have radiocarbon dated a few ibex bones and also charcoal samples from the main fireplace and other smaller charcoal deposits we found scattered around the room’s floor. The chert artifacts were examined in detail and their typology classified accordingly. U-Th dating of calcite from speleothems helped us reconstruct this hypogeal environment at the time it was frequented by man. We also studied a puzzling deposit of speleothem crust slabs piled up in a corner of the cave, which may represent a funeral earthen mound. All in all, the absence of artifacts other than the four chert blades, the few ibex bones, the one main fireplace and three other minor charcoal deposits in the room, and the probable earthen mound located tens of meters underground from a now debris-sealed entrance, lead us to hypothesize that this cave room does not represent a residential dwelling but rather a worship place sporadically utilized by few representatives of a local Epigravettian hunter community.

Abstract