Magnetic field anomaly map hand drawing by Nijolė Gedvilaitė 1976, maps published by USSR Ministry of Geology, 1963, geological sample boreholes location data: Lithuanian Geological Survey, Estonian Land Board, Latvian Environment, Geology and Meteorology Centre.
Measurements in the magnetic field are varying in different locations due to the composition and structure of the Earth's crust. Magnetic field anomaly maps were used for further geological surveys and geophysical modeling that determined locations for borehole drilling to extract core samples in geological surveys for mineral resources. The Magnetic field anomaly maps edited by Nijolė Gedvilaitė and maps published by USSR Ministry of Geology are overlaid with core sample location data highlighting the relationship between the measurements and interventions to acquire geophysical data and research approximating mineral resources.