Abstract. Shatter cones are a sign of impact metamorphism and are usually considered in the context of impact structures. However, they can be formed in another way. In recent years, very similar formations have been described on the Outer Islands of the Gulf of Finland (Moshchny, Gogland). This paper presents shatter cones on rapakivi granite boulders, studied by the authors in 2023 on the shore of the Gulf of Finland in the village of Fort Krasnaya Gorka, Lomonosov district, Leningrad region. These shatter cones were apparently formed because of abrasion of the Litorina ledge approaching the coastline: when moraine boulders fell from above (the modern height of the cliff in this place is up to 20-25 m) and their collision. In total, we discovered at least 70 obvious shatter cones on a section of the coast of 300-400 m long. This indicates sufficient conditions for the formation of such structures without meteorite impact. We assume that similar shatter cones can be found in other coastal places - where there is a sufficient height of the abrasion ledge and numerous boulders of crystalline rocks.

Keywords: shatter cones, impact metamorphism, abrasion coast, rapakivi granite boulders, Krasnaya Gorka