CAVES AS SEA LEVEL AND UPLIFT INDICATORS,KANGAROO ISLAND, SOUTH AUSTRALIA

摘要

Flank margin caves have been observed in Quaternary BridgewaterFormation eolianites on Kangaroo Island, South Australia. Horizons of flank margincave development at 25 m, 30 m, and 35 m elevation demonstrate tectonic uplift of tensof meters during the Quaternary, as the cave elevations are higher than any reportedQuaternary glacioeustatic sea-level highstand. Distinct cave horizons indicate thatepisodic uplift was possible. Wave-cut notches at Hanson Bay, at 30 to 35 m elevation,also support the interpretation from caves that relative sea level was once at the —30-m-elevation range. Admirals Arch, previously presented as forming solely by wave erosion,is a flank margin cave breached and modified by wave erosion. Point Ellen contains aLate Pliocene subtidal carbonate unit that formed within the reach of wave base, wasuplifted and cliffed by wave processes, and then was karstified before being buried byQuaternary Bridgewater Formation eolianites. A possible flank margin cave developedat Point Ellen at 3 m above modern sea level is consistent with earlier interpretations ofnotching of the nearby coast at a similar elevation during the last interglacial sea-levelhighstand (MIS 5e); and therefore, no tectonic uplift in the last 120 ka. In contrast, thetafoni of Remarkable Rocks present a cautionary note on evidence of cave wallmorphological characteristics as proof of dissolutional origin.