Lichens of erratic block rocks of Podlaskie Uplands

On post-glacier granite rocks of Podlaskie Uplands a rather abundant-lichen flora characteristic for the lowlands is present. 69 species of lichens have been found among the rare ones in the investigated region are <i>Parmelia sorediala, Thelocarpon laureri, Bacidia albescens</i>. Three associations have been distinguished: <i>Lecideetum crustulatae, Parmelietum conspersae, Physcietum dubiae.

An investigation into the genesis of an erratic (retro) eclogite block from Haren, Groningen, the Netherlands

In boulder clays and glacial deposit sands, exposed in the northern part of the Netherlands, erratic blocks of (ultra)high pressure (UHP) metamorphic rocks may be found that originate from the Baltic Shield (Scandinavia). The occurrence of (U)HP metamorphic rocks in Scandinavia is limited to: (1) isolated occurrences within the Scandinavian Caledonides (Western part of Scandinavia); (2) Sveconorvegian rocks from the Halland area, Southwest Sweden; and (3) Kola Peninsula (Northern Scandinavia). For this reason (U)HP rocks form excellent indicator pebbles/rocks that may be used to trace back the source area from where the erratic blocks, found in the Netherlands, were derived. An example of this, an erratic (retro) eclogite block found in Haren, is investigated in the present study using naked eye, light-optical and electron microprobe (EMP) techniques. EMP mineral analyses were used to reconstruct the PT conditions under which the (retro) eclogite was formed (T = 756 °C/min. P = 16,2 kb). This result, in combination with the mineral chemistry of the major rock forming minerals, provides evidence that this erratic block originates from the upper HP tectonic lens exposed in the Caledonian Seve Nappe Complex of Northern Jämtland, Sweden.