The Ruokolahti church and surrounding buildings were built on terrain deposited by the glacial river and is dotted with kettle holes. Kettles formed as large blocks of ice were buried in the sand and gravel at eskers and deltas formed by glacial rivers. As the ice blocks gradually melted away, holes of various shapes and sizes were left behind. The area of church hill is bordered in the west by Ukonsalmi, a former glacial bay which was formed as the ice sheet deeply eroded the bedrock’s fault zone. The fault is one of the largest in the Geopark area. At Ukonsalmi it is 26 metres at its deepest. Geology is also visible in the church’s foundations, as its cornerstone contains a diverse range of stones in the area, which includes garnet-cordierite mica gneiss and granite boulders.