VSA General Meeting (September)

The next meeting is to be held on 4th September 2024.

Venue is Kathleen Syme Library and community centre and via Zoom link.

Emeritus Professor John Webb will present   “Origin of the tropical monsoonal karst of northern Australia”

Synopsis : The major northern Australian karst areas (Bullita, Kimberleys, Colless Creek, Katherine, Chillagoe) have variable geology (flat-lying to subvertical dolomite and limestone), but experience a similar monsoonal climate (short wet season with intense rainfall events, long dry season) and have similar karst and cave features: well-developed surface karst (towers, pavements, rillenkarren) and joint-controlled maze caves with tall, narrow passages that are typically widest at the base. Cave development under the monsoonal climate occurs from the top down, as runoff from wet season torrential downpours enlarges the numerous vertical joints cross-cutting the limestone over an entire pavement/tower to form joint-controlled maze caves. However, for significant cave development, a moderate-high hydraulic gradient is also required, provided either by the relief of the karst towers or stream incision through the limestone outcrops following late Tertiary uplift. Karst development may have started when Australia drifted northwards into the monsoon zone in the last 10 million years.

John Webb (PhD UQ 1982) is Emeritus Professor of Environmental Geoscience at La Trobe University. He specialises in geomorphology, particularly landscape evolution and karst geomorphology of limestone regions. He also works in geoarchaeology, groundwater and contaminated site management. He has supervised 108 honours students and 30 PhD students, and published over 150 papers. With Susan White and Garry Smith, he edited Australian Caves and Karst Systems, published in 2023 by Springer.