Suuri Sarviniemi and Pieni Sarviniemi are end moraine ridges surrounded by water in the Second Salpausselkä. They were formed when the melting ice sheet came to temporary stops 11,800-11,600 years ago. Depth curves of the lake bed show distinct underwater extensions from both ridges across Rastinvirta. Since the waves have washed away both ridges in the Sarviniemi area, particularly during the Greater Saimaa phase, the boulder content of the deposited material is emphasised on peninsulas. A comprehensive collection of rock types, granite and gneiss typical to the area can be seen on the northern shore of Suuri Sarviniemi.