GYROLITHES AS AN INDICATOR OF SHALLOW WATER DEPOSITION IN THE AUSTIN CHALK NEAR WACO, TEXAS, USA

Gyrolithes, a helical marine trace fossil, is discovered to occur in beds of the Austin Chalk near Waco, McLennan County, Texas. Irregular bedding features associated with Gyrolithes at this locality indicate deposition during a storm-influenced turbidity episodes, which are interspersed with periods of quiescence allowing for firm ground formation and colonization by the trace maker. Gyrolithes is associated with marginal marine settings in other localities, but has not ever been associated with storm deposits; therefore, this discovery constitutes an expansion of environment for this ichnogenus.