The Holtäkt conglomerate has been found in a glacial drift 9 km north of Falun. It is a conglomerate or sedimentary breccia with cpiclastic and/or pyroclastic matrices. The pebbles, often angular, are of gncissic granite, primorogenic diorite and gabbro, various metavolcanics (leptite formation) and mctascdiments. The matrix is a quartz sandstone, or a basaltic tuff. K-Ar age determination of the tuff has yielded 1504 ± 18 Ma, indicating that the Holtäkt conglomerate has to be referred to the Digerbcrg formation of central Dalccarlia.