意大利的Gubbio和丹麦的Stens Klint海相白垩系—第三系界线含铱粘土层,被阿尔瓦雷斯等人当作是陨星撞击地球扬起的尘埃形成尘埃云快速回降而成。而对Stens Klint界线粘土的矿物学研究表明,这层粘土不是外来的,它与其上下的、从当地衍生的粘土没有区别,其中富集的金属元素大多数来源于下伏白垩层中已融化的火山碎屑,而陨石成分最多只有20％或更少。在意大利的Gubbio,铱的富集是分布在界线之下2米到界线之上2米,估计其形成时间约40万年。还有几个海相剖面却显示出有多个铱异常层。例如,德国南部巴伐利亚州阿尔卑斯山北坡的Lattengebirge白垩系— Gubbio in Italy and Stens Klint in Denmark Marine Cretaceous - Tertiary Boundary containing iridium clay layer, by Alvarez et al as a meteorite hit the Earth raised dust dust cloud formed quickly back down. Mineralogy studies of the Stens Klint clays indicate that this layer of clay is not alien and that it is indistinguishable from its top and bottom, locally derived clays, and most of the metal elements that are enriched are derived from the melted Volcanic debris, and meteorites up to only 20% or less. In Gubbio, Italy, the enrichment of iridium is distributed over a distance of 2 meters below the boundary to 2 meters above the boundary, and its formation time is estimated to be about 400,000 years. There are several sections of marine facies that show multiple iridium anomalies. For example, the Lattengebirge Cretaceous on the northern slopes of the Bavarian Alps in southern Germany -