Abstract: A sequence of marine volcanic rocks （the Erdaogou Subformation） up to 1000 m thick is developed in the central part of the Wumishan Formation of the Jixian System in the Xunhe area in northern Liaoning. This paper briefly describes its stratigraphic position, its contact relationships with the overlying and underlying strata, and its mineralogy, textures and structures and petro- chemistry. This sequence is represented by spilite （or albitized basalt） with a pillow structure, intercalated with a lot of sedimentary rocks such as sandstone, slate and dolomite, belonging to the product of volcanic eruption and sedimen- tation in marine environments. This implies that intense volcanic eruption took place in the middle Miwushaian stage of the Jixian period in the area. This situation is quite different from the structural and depositional environments in North China and other regions.