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Multidisciplinary research (including magnetic survey, earth resistance survey, geological mapping, detailed archaeological surface survey and geochemical prospection) was undertaken on an area of about 0.7–9.0 hectares (depending on the method) in the close surroundings of the medieval ring-fort relicts in central Poland. The geophysical studies of the vicinity of the Rozprza ring-fort were part of a multi-method complementary non-destructive archaeological survey. The ring-fort is situated in the Luciąża River (Vistula River basin) valley floor and the flood plain morphology is very important for the reconstruction of palaeoenvironmental conditions of settlement location. Results of aerial photographs and geophysical prospection allowed the discovery of traces of sub-fossil palaeomeanders of different sizes as well as relicts of archaeological features (system of ramparts and moats). It was possible due to the application of high resolution archaeo-geophysical surveys. Both natural structures and also anthropogenic features registered with geophysics have been verified by geological sounding. The surface geology structure of the close vicinity of the ring-fort has been recognised in detail and selected organic deposits of palaeochannel fills and overbank covers have been14C dated. The Rozprza ring-fort was situated in a defensive location on the surface of a sandy terrace remnant in the central part of a (partly) swampy valley floor. The accumulation of recorded fills of palaeochannels and moats covers the whole Holocene, as documented by14C data. It gives the possibility for future detailed palaeoenvironmental studies. The results of geophysical studies, due to their known precise location, allow the effective planning of further research activities, both archaeological and palaeoenvironmental.

The Rozprza motte‐and‐bailey residence in Central Poland was inhabited from the third decade of the 14th century up to the 15th century A.D. and functioned as a seat of a noble family. It was situated in the place occupied previously by an Early Medieval open settlement and a later ring‐fort. The motte was constructed on the river terrace remnant adjoining a strongly expanding flood plain in the central part of the mid‐Luciąża River valley. The immediate surroundings of the stronghold were studied by means of archaeological excavations, detailed geological mapping (hand‐auger transects and trenching), and large‐scale aerial photography, as well as geochemical and geophysical (magnetic gradiometry and soil electrical resistance) prospection. All the results have been integrated within a GIS and supported by a set of 14C dates that allow for a detailed geomorphological reconstruction of the stronghold situation, including former river patterns, the local flood plain development, and the history of the Medieval fortress site with its moats. Our research provides insights into the late Holocene evolution of a small river valley and confirms the favorable conditions for the location of the motte on a terrace remnant protected by the system of moats and surrounding paleochannels and swampy areas within the valley floor.

During archaeological excavations of a medieval stronghold in Rozprza, a buried thick deposit of deep black (Dark Earth type) soil was discovered. A multianalytical (sedimentological, geochemical and archaeobotanical) study was carried out in order to identify traits the Rozprza Dark Earth. The analyses demonstrated that the soil was formed as an effect of surface accumulation of organic deposits from swampy areas and waste materials with rich admixtures of organic materials. The organic carbon content of the soil of the Rozprza Dark Earth was twice as high, and the total concentration of P was many times higher as compared with the adjacent soil outside the stronghold. Plant macroremains which were recorded within the buried soil and a cultural layer are evidence for human activity, mainly wood gathering and agriculture. In the Early Middle Ages, summer crops could be cultivated there with the use of tilling methods characteristic for root crops or gardens. The accumulation of the Rozprza Dark Earth commenced in the second half of the tenth century AD. In the period between the eleventh and thirteenth century, a ring-fort was established there. The deep black soil is partly covered by the ring-fort's rampart. The rampart was built with the use of re-deposited earlier cultural layers and sand of the subsoil. It was then clad with sod bricks. Such a construction of a medieval rampart has been recorded for the first time in the territory of Poland. A new interpretation of archaeological structures and cultural layers offers a basis for new conclusions concerning the chronology and the development stages of the medieval settlement and ring-fort in Rozprza.

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