The Quaternary Drilling at the Rehhag under the supervision of members of the Institut für Geologie (QDR-RE-IfG) was interested in the unconsolidated sediment infill of a bedrock trough in the Northern Alpine Foreland (NAF). Such bedrock troughs, now hidden beneath their sediment infill and/or in lakes, occur in formerly and currently glaciated areas, and are linked to increased glacial erosion. The base of these bedrock troughs is located beneath today's base level, which puts them beyond fluvial erosion, and this is why they are referred to as over-deepenings. Such overdeepenings can be found in the vicinity of the Alps which includes the NAF. After the formation or re-occupation of such overdeepenings by glacier ice these troughs provide accommodation space for the deposition of sediments. Hence, overdeepenings are likely to preserve sediments through glacial-interglacial cycles. As erosive agents, glaciers re-shape landscapes, and excavate and re-use sediments of previous glaciations which makes the preservation of intact sedimentary sequences through multiple glacial cycles unlikely. These repeated cut-and-fill cycles limit the Quaternary sedimentary record and make the investigation of the number and chronology of Quaternary glacial-interglacial cycles difficult. Overdeepenings, however, can preserve fractionated and probably intact sedimentary sequences throughout multiple glaciations. Hence, accessing the sediment infill of overdeepened bedrock troughs through core drillings provides insight into phases of the Quaternary at locations where formerly little information was available.
To gain new insight into the Mid- to Late-Pleistocene sedimentary record in the Bern area (Switzerland) the drilling QDR-RE-IfG was conducted in Bern-Bümpliz, where a minor branch of the Aare Valley overdeepening is located in which Quaternary sediments at least 150 ka in age were expected. In Bern-Bümpliz, at the Rehhag, the uppermost 30 m of the sedimentary succession are accessible in an abandoned clay pit. The drilling reached 211.5 m driller's depth, recovering 208.5 m of unconsolidated sediment and, below a sharp contact, 3 m of Miocene Molasse bedrock. The recovery of intact core from unconsolidated sediment is challenging. Nevertheless, 92.3% of the core material was recovered in 1 m-long plastic liners in pristine condition. As the drilling reached the bedrock it is the first scientific drilling that recovered the full sedimentary suite in a part of the Aare Valley overdeepening. Within the sedimentary succession two sequences (A = lower, B = upper) were identified. Each of the sequences is initiated by the deposition of glacial till that is overlain by lacustrine or glacio-lacustrine sediments. First luminescence ages indicate a depositional age between 250 and 340 ka for sequence B.
The drill core was transported from the drill site to the Institute of Geological Sciences, University of Bern, where it was analyzed and sampled. The first step in the analysis was scanning the whole core contained in the liners on a Multi Sensor Core Logger (MSCL; Geotek Ltd.) which provided measurements of the core (γ-)density, p-wave velocity and magnetic susceptibility. The liners were then opened under light sensitive conditions, the cores split in half to allow their macroscopic description, and one half was sealed from light and other alterating influences. After the description, the core was documented with a digital line scanner on the MSCL. After the documentation, a vane meter was used to determine the shear strength of the material and samples for pollen analysis, analysis of the carbon content, provenance analysis, and the measurement of cosmogenic nuclides 10Be and 26Al were extracted.
This report provides limited information about the drilling operation, describes the available datasets form scanning and sample analysis, and the results of the first data processing as well as the tools used in the data analysis.
The data set ": Soil physical and hydraulic properties along two chronosequences of proglacial moraines" consists of several individual files in tabstop delimeted text format. The data set contains soil physical data from two chronosequences of moraines in glacier forefields in the central Alps, Switzerland. Aim of the study was to investigate the impact of age and parent material on soil physical characteristics. At the forefield of the Stone Glacier the moraines developed from silicate parent material (S) and at the forefield of the Griessfirn from calcareous parent material (C). At each forefield disturbed and undisturbed soil samples were collected from four moraines of different ages and porosity, bulk density, particle size distribution, gravel content, ignition loss, retention curves and unsaturated hydraulic conductivity curves were determined. Per moraine, three sampling sites were identified based on the level of vegetation complexity [low, medium, high] (for details on this vegetation classification see Maier et al., 2019).
Two sampling locations spaced 3 to 4 m apart were selected per vegetation complexity at each moraine. These different sampling locations are identified in the files as location 1 and 2. Data sets from the moraines developed from silicate parent material are marked with S and data from the moraines with calcareous parent material are marked with C. For the C forefield bulk density, porosity and ignition loss are listed in a single file. For the S location the ignition loss data is listed in a separate file from the bulk density and porosity data. In each file the sample type, the sample volume, the sample number, the moraine age, the sampling depth, and the level of vegetation complexity are provided. The particle size distributions of the fine earth and the gravel content are also listed in individual files. Again, the sample number, moraine age, vegetation complexity, sampling depth and sampling location are noted in the files.
For the retention curves and the unsaturated hydraulic conductivity curves, two files exist for each curve and glacier forefield, which are named accordingly with the glacier forefield identification and type of curve. An overview file for each glacier forefield contains a list with the sample number, moraine age, sampling depth, vegetation complexity and sampling location. The other two files per curve contain the lab measurements. For the retention curve data, the sample numbers link the pressure head [cm] values provided in one file to the corresponding volumetric water content [-] values provided in the other file. The same applies to the hydraulic conductivity curve where the sample number now links the unsaturated hydraulic conductivity [cm/h] to the corresponding pressure head [cm].
The described dataset was the result of a field effort consisting of several campaigns to assess the influence of carbon increase as a result of agroforestry treatments on soil hydrological characteristics and water fluxes at two sites in Malawi. At the sites, two experimental trials have been established which differ in age and soil characteristics, while climatic conditions are roughly comparable. At both sites we focused on control plots of maize and agroforestry treatments including Gliricidia sepium (Jacq.) Walp. as the tree component. The dataset contains soil characteristics such as texture, porosity, carbon and nitrogen concentrations, carbon density fractions, dispersible clay proportions, soil hydraulic conductivity and water retention curves. To assess the differences in water fluxes between treatments and sites, we installed soil moisture and matric potential sensors and a small weather station at the sites and monitored the fluxes over the course of about three months. The resulting time series are also part of the dataset, as well as some measurements of maize heights. The file structure of the dataset as well as details on the sites, sampling procedures, measurements and methodology are included in the data description.