Facies and Facies Sequence of Modern Transgressive Barrier Island, Cedar Point, Ohio

Thomas F. Bray, Jr., Charles H. Carter

The southernmost, unprotected, 1.8-km stretch of the Cedar Point spit has migrated about 1.5 km landward in the last 15 years. The movement of the 30-m wide barrier is episodic, with migration of up to 15 m in a single, northeast wind storm. Migration occurs primarily by washover, but also by channels breaching the barrier.

Four main environments typify the barrier: foreshore, windflat, washover fan, and lagoon. Each environment is typified by a specific facies. The foreshore facies is characterized by medium sand that makes up truncated laminations which dip lakeward about 5°. The windflat facies is characterized by coarse sand that makes horizontal to subhorizontal landward-dipping laminations and infilled scours. The washover fan facies is characterized by coarse sand and granules that make up foreset beds that dip landward at about 25°. The lagoon facies is characterized by intercalated peat and clay. Sequences consist, from bottom to top, of an intercalated brownish-black peat and clay, a cross-bedded medium to coarse sand, and a laminated medium sand with abundant heavy minerals.

The barrier is transgressing because of the paucity of sand in the longshore transport system and record-high lake levels with associated wind storms. If preserved, the stratigraphic record will consist, from bottom to top, of mudstone and coal, steeply dipping cross-beds, and gently dipping laminated sands. These facies represent lagoon, washover fan, and windflat environments.

AAPG Search and Discovery Article #91041©1987 AAPG Eastern Section Meeting, Columbus, Ohio, October 7-10, 1987.