Sediment drilling of the Eemian interglacial in Kurikka
A scientific drilling and sampling operation was done in Kurikka on 9.-10.1.2025, as part of research by the University of Oulu. The objective of the study is to improve the precision of sediment core sequences from the Eemian interglacial period, which occured between ice ages.
The drilling was performed using a piston corer connected to a Geomachine GM 200 drilling rig, which is commonly employed for undisturbed sampling of basin sediments. Two samples were collected from different depths at the site. The first sample was taken from a depth range of 31.80-36.50 meters, and the second from 38.00-45.50 meters.
Experienced drilling team
The six-member drilling team that conducted the operation brought a wealth of experience and expertise to the project. Drillers Petri Pehkonen and Jarno Moilanen from Ramboll Finland have been working in the Kurikka region for several years, and the team was further strengthened by Seppo Putkinen, who returned briefly from his retirement days to help with the project.
Representing the University of Oulu were Professor Juha Pekka Lunkka and University Lecturer Tiina Eskola. From the Geological Survey of Finland (GTK), researcher Niko Putkinen was present; he has been involved in the geological and hydrogeological studies of Kurikka from the very beginning.
The success of the drilling operation was far from guaranteed, as the team faced several challenges along the way.
Interview with Ramboll Driller Petri Pehkonen
Interview with Seppo Putkinen
Difficulties caused by dense sediments.
The targeted basin sediments are located beneath the basin sediments of the current interglacial period and the moraines formed during the preceding glacial period. Due to the pressure exerted by the continental ice sheet, the sediments deposited during the Eemian interglacial were densely compacted, which made it challenging for the samples to penetrate into the core barrel.
Despite these difficulties, the team successfully completed the drilling operation and transferred the samples into storage for further processing. The next steps involve opening, preparing, and analyzing the samples.
Fruitful research environment of Kurikka
According to University Lecturer Tiina Eskola, the thick organic sediment layers beneath the moraine in the area are rare and provide researchers with a unique opportunity to study the ancient environment. These layers serve as an archive, allowing the reconstruction of past vegetation, climatic conditions, and the water quality of the basin during the time of sediment deposition.
The sediment samples from Kurikka will be studied not only for their microfossil content but also for the physical and geochemical properties of the sediments. Additionally, researchers will investigate the potential impact of the organic sediment layer on the quality of the area’s groundwater.
Interview with University Lecturer Tiina Eskola, University of Oulu
Significant research for the future
The research is a scientifically significant project that deepens our understanding of the geological history of the area. The results will not only advance the study of the ancient environment but also contribute to the management of groundwater quality and hydrogeology in the region for the future.