CoachA life assemblage is a group of fossils of organisms that lived together, preserved where and as they lived; a death assemblage is a group of remains brought together after death, which may mix organisms of different places and different times. A fossil is autochthonous if it is preserved where the organism lived, and allochthonous if it was transported from elsewhere before burial.
示例
Example 20.10 (The base of the Varden cover)
The sandstone holds channel fills on scoured bases, roots and plant fragments, and no marine fossil: it was laid down by rivers on land. The oolitic limestone above has cross-bedded ooids, which grow as they roll in agitated water, vertical tubes and U-shaped burrows of the Skolithos ichnofacies, and worn shell fragments, all allochthonous: a shoal of the shoreface, swept by waves. Between the two the sea arrived: the contact records a marine transgression. In the order of Walther’s law, the river plain was followed by the shore, then the shoal.