A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #0-9

., . (1988) ( ) // , .XLIX, .1, .1-10, 3 ., II .

The Svistov Formation crops out in the area of the town of Svistov (Central North Bulgaria). It is represented b sandstones and mixed terrigenous-carbonate rocks and overlays the Trambes Formation. The two units gradually interfinger to the north. Repre; sentatives of several organism groups ,were found in Svistov Formation. There are different opinions J the stratigraphic range of the formation, but in the last two decades it was referred to the Albian Stage. The new m monite collection from these rocks and the revision of fossil material collected b previous authors prooves definitely that the formation belongs to the Upper Aptian (Clasayesian) Substage. Four section of the formation are described in the studied area. Two ammonite zones in the Upper Aptian Substage are indicated - . nolani Zone and . jacobi Zone.