Bioturbational cross bedding and Bioturbational lamination

Abstract**

We describe three biogenic fabrics that result from Zoophycos burrows: cross-bedding, lamination, and cross lamination. (1) Bioturbational cross-bedding is produced by spreiten whorls that do not parallel the physically-produced bedding, (2) bioturbational lamination is produced by the extensive compaction of subparallel Zoophycos whorls, and (3) bioturbational cross lamination results when superposed whorls cut and remove about half of the superjacent or subjacent whorls. Recognition of these bioturbational structures is critical to the correct interpretation of depositional structures and history. Because they are excavated within the sediment by infaunal burrows, both tops and bottoms of prior structures are truncated, and the resultant contradictory "tops" as deduced from cross-cutting relationships are diagnostic field criteria for a bioturbational origin. Our examples are from the Esopus and Carlisle Center formations in Lower Devonian outcrops of New York State.

**Thayer, C. W. and Y. L. Bordeaux, in review.  Parallel- and cross- 
	stratification produced by bioturbation: Zoophycos burrows in the 
	Lower Devonian of New York State.