During many years' research, the stratigraphy of Quaternary deposits in the area surrounding Konin has elaborated. In the young Quaternary strata the Eemian fossil lakeland was established and the exposed Mikorzyn section was found. Previous geological and palynological analyses of the site prove a nearly complete sequence of Eemian and Vistulian deposits. Furthermore, archival records of drill cores indicate that older interglacial sediments may also have been deposited about 10 metres deeper in this particular area. To test this possibility, a relatively deep test borehole -- Mikorzyn 1 was carried out in the distance about 70 metres only. The sedimentological and palynological core analyses prove the Eemian age of examined organic materials. The borehole, established only the presence of ca.10 m offset in the bottom part of the Eemian strata. This fact, as well as other faults and Tertiary coal injections into glacial sediments, confirmed the occurrence of neotectonic activity.