THE WORLD’S OLDEST CAVES: - HOW DID THEY SURVIVE AND WHAT CAN THEY TELL US? NAJSTAREJŠE JAME NA SVETU: KAKO SO SE OHRANILE IN KAJ NAM LAHKO POVEDO? R. Armstrong L. OSBORNE 1 Izvleček UDK 551.44(091) R.A.L. Osborne: Najstarejše jame na svetu: kako so se ohranile in kaj nam lahko povedo? Deli odprtega jamskega sistema, po katerem se lahko danes sprehajamo, so stari več kot 300 milijonov let. Zdrav razum celo takemu navdušencu, kot sem jaz, pove, da tako stare odprte jame ne morejo obstajati, a vendar so! Da so se ohranile, je lahko deloma vzrok v izredno počasnem zniževanju površja, toda to samo po sebi ni dovolj. Jama je morala biti najbrž tudi zasuta in s tem odrezana od sveta, potreben pa je bil tudi rela- tiven navpičen premik ob prelomih. Zaenkrat je bil najden en sam niz zelo starih jam, ali jih je morda še več? Kaj nam lahko povedo? Ključne besede: speleologija, najstarejša jama, ohranitev starih jam. 1 R.A.L. Osborne, Faculty of Education and Social Work, A35, University of Sydney, NSW 2006, Australia; e-mail: a.osborne@edfac.usyd.edu.au Received/Prejeto: 27.11.2006 COBISS: 1.01 TIME in KARST, POSTOJNA 2007, 133–142 Abstract UDC 551.44(091) R. Armstrong L. Osborne: he world’s oldest caves: - how did they survive and what can they tell us? Parts of an open cave system we can walk around in today are more than three hundred million years old. Common sense tells even enthusiasts like me that open caves this old should not still exist, but they do! heir survival can be partly explained by ex- tremely slow rates of surface lowering, but this is not suicient by itself. Isolation by burial and relative vertical displacement by faults are probably also required. Now one very old set of caves have been found, are there more of them? What can they tell us? Key words: speleology, oldest cave, survival of old caves. INTRODUCTION In June 2004, when I last spoke here at Postojna about dating ancient caves and karst I found it diicult to not to reveal the exciting discovery which this paper follows (see Osborne, 2005). My collaborators and I had been convinced since mid 2001 that sections of Jenolan Caves in eastern Australia had formed 340 million years ago. We had to ensure that our story was published and that we could convince others. he issue was not whether the dates themselves were correct, but did the evidence really mean that the caves containing the clays were of such a great age. his took four years of intensive work on the clays and additional dating. Now ater the publication of the results (Osborne et al, 2006), and the following media interest; it seems appro- priate to relect on the signiicance and implications of the survival of Early Carboniferous open caves.