This paper is a presentation of the results of extensive studies in the framework of methodical researches of rock properties and spatial deposition of layers in the main petroleum basins of the Polish Lowland between the Oder and Bug Rivers. The Polish digital cartography method, often foregoing and original, has been elaborated by the Author (S.F.J.) for the recent 30 years. The concept of digital petroleum cartography is not based on any other patterns partly known from literature or conditionings related to the quality or quantity of information. For this reason in numerous publications it has been labelled as the Polish digital cartography method. The geological concept and the selection of accurate data has been assumed in line with the classical surface cartography and then its principles have been introduced to data processing, software and final caIculations. The eventual pictures have been analysed in co-operation with the top class Polish computer scientists. Among such specialists is the main representative of the specialisation Mr. Ryszard Weinar, PhD who constantly performs the most important activities related to calculations with the use of the electronic graphical apparatuses - first ones made in Poland then also foreign products. The study of the spatial system of layers in petroleum basins required uniformisation of all co-ordinates of the analysed driIling data, not only weIl profiles, but also seismicity profiles, to one Polish system. Initially this was a local system, then the generaIly accepted Borowa Góra system and recently the system 42 (fig. 1, 2, 15a, b, 16a, b). The number of the analysed seismicity and drilling data was presented on the background of stratigraphic horizons in the form of figures Iisted in Tables for the Cretaceous (Cr1), Jurassic (J1), Triassic (T1), Zechstein (P2), Rotliegend (P1) and Carboniferous (C1) and older basement, mainly Devonian (D). The quantitative analysis of the drilling and seismicity data in the Carpathian Foredeep were limited to one stratigraphic border, surface of discordance of the Miocene with the older basement. Thus all the enumerated data were mainly referred to the bottoms of the mentioned geological formations. It has been assumed in the model that they correspond to the surfaces of angular discordances, and considerable facial and Iithological changes for the Zechstein and Rotliegend, which has been proved by the drilling and seismicity surveys. The number of the analysed seismicity and drilling data for each of the enumerated horizons can be thousands. It was important to determine the class of size and num ber of apparent angles of dipping (tab. 1). In the course of the detailed analysis of these unquestionable data, prepared in co-operation with specialists from numerous units of the Polish Petroleum Mining Company, there were prepared digital structural maps (Fig 3-10) for the Upper Cretaceous (Cr2) bottom, the Lower Cretaceous (Cr1) bottom, the Upper Jurassic-Malm (J3) bottom, the Jurassic (J) bottom Iying discordantly on the older basement or other elements also Iying transgressively, e.g. Doggerian (J2), Lower Triassic (mainly T1) or older formations Iying transgressively: Zechstein bottom (P2), Permian bottom (P1) and also bottom of the transgressive Carboniferous (C1 or C2) deposited discordantly on the older basement of the Polish Lowland. In the Carpathian Foredeep special attention was paid to one discordance, being the main angular discordance between the Miocene (M1) and its Mesozoic platform basement: mainly Cretaceous or Jurassic, Palaeozoic: mainly Carboniferous, Devonian or Cambrian, and in the vast area - Proterozoic - in the form of phyllite series building up the Lower San River anticlinorium (fig. 17a, b). After making these maps, initial contour cuts were made every 250 metres to provide the readabiIity of the maps in the scale 1 : 2500 000 and 1 : 4 000 000 for the Polish Lowland. Apart from this, a set of exhibition maps were made in a more detailed scale, mainly 1 : 200 000. The objective of these studies was the analysis of the spatial system of layers over the surfaces of angular discordance, and so determination of the structural Ievels. In the Carpathian Foredeep the spatial system of angular discordance in the Miocene bottom consisted of two parts: between Cracow and Tarnów and Rzeszów and Przemyśl in the east in the scale 1: 500,000 and as exhibition maps in the scale. 1 : 250,000. Based on these digital structural maps, digital depth maps could be made in the scale 1: 2,500,000, usually for four horizons: -1,500 bsl, -2,000 bsI, -3,000 bsl. (fig. 11-14). Thanks to the great number of seismicityand drilling data, the pictures obtained in horizontal planes made it possible to interpret them both in view of potential upliftings or lowerings. Four selected depths stay witllin the range of the most common discovered hydrocarbon deposits. Five depth horizons were selected in the Carpathian Foredeep: -1,000 bsl, -1,500 bsl, -2,000 bsl, -2,500 bsl, -3,000 bsl, but in a more detailed scale l : 500,000 (fig. 18a, b-22a, b). The interpretation of the obtained digital depth maps enabled: 1. Analysis of structural series, 2. Successive uncovering of shallower geological formations, 3. Localisation of perspective areas, 4. Quantitative analysis of anticlinal elevations, synclinal upliftings and monoclinal zones, 5. Differentiation of primary and secondary properties of the spatial system due to, e.g. conditions of sedimantation, style and causes of folding and other deformations of layers caused by, e.g. liquidity of Zechstein salts at greater depths. This elaboration led to the first publication of a fully original methodic approach (not based on literature) in the light of numerous data and activities related to their processing and reliable quantitative interpretation. The most crucial conclusions are as follows: 1. Data preparation, 2. Calculation method, 3. Horizontal depth cuts as a criticism of interpretation maps, 4. Analysis of surfaces of angular discordance, 5. Lack or limitation of discordant, fault tectonics known from many publications. The main advantage of the elaboration lies in the comparison of distribution of the analysed data with the obtained digital structural maps as a significant study of application and check of the Polish digital petroleum cartography.