Abstract In 2011 the last phase in the installation of the PRACLAY In-Situ Experiment in the underground research facility HADES (Mol, Belgium) was completed. The main goal of the experiment is to perform a large-scale in-situ Heater Test. The Heater Test will examine the effect of the thermal load generated by heat-emitting waste on Boom Clay, currently considered as a potential host rock in the Belgian R&D programme for geological disposal. In 2007 the PRACLAY gallery was constructed to host the Heater Test. In 2010 a bentonite-based hydraulic seal was installed in this gallery, isolating the heated part from the non-heated part of the PRACLAY gallery. The primary objective of the seal is to provide undrained hydraulic boundary conditions for the Heater Test. As the performance of the seal is crucial to the Heater Test, it has been instrumented accordingly. The seal also provides an opportunity to gather additional information on the in-situ behaviour of bentonite-based repository structures. Finally the placement of a heating system and water-saturated sand in the heated section of the PRACLAY gallery completed the experiment installation. The water-saturated backfill sand has to assure undrained hydraulic boundary conditions at the interface between the clay and the gallery lining.

Abstract Radiolarian skeletons are known from a limestone concretion collected from a black shale succession and from black cherts of the Yangtze Platform, China. Both occurrences are of earliest Cambrian age. The findings, reported in this paper, represent the oldest known fossil Radiolaria. Their spherical skeletons display a morphology typical of spherical radiolarians from Ordovician and younger faunas. This occurrence of radiolarians with radial symmetry and, most probably, a planktonic lifestyle can now be traced back into the earliest Cambrian. Thus, radiolarians have been part of the early oceanic plankton and likely played a significant role in the silica cycle of the oceans along with siliceous sponges.