'nolJIast afeOUt 4 in. by 4! m. had u 

 number of small pieces adhci nig, in- 

 judiug <M>* of a few nunces weight. 

 rhes o were probnhly fragment* ot 

 A rock originally attached, because 

 and! were b'oken surfaces, while the 

 m |gc of the largest pitce was eroded 

 picciseh to the curvature ot the held- 

 fxii edee. and was luundcd similarly 

 ,, foe piece illustrated. A small hold- 

 fey 2 111. by 3i m. had a thin pkile 

 „f ioek attached. The side adhering 

 lo the holdfast was white c.ilcium 

 crbonatc. seams of which ate eotn- 

 foffl ni the rocks of the area. Over 

 a bout hall of the area was a layer 

 oi nrkcisc. which was part ot' the rock 

 intruded by the tttfcfc band. The 

 majority of the white carbonate 

 surface was covered with a recent 

 bruwoan. showing lhal 



I. I he hryo/oan ptcfeircd the 



eaibonate as an attachment 

 2 Since the rock was plucked 

 from the oulciop. and before 

 it was east ashore, the brvo- 

 zoan h«»il tune to grow 

 Some holdfasts at lirsl glance 

 appealed to have no rock attached. 

 b„l closer examination revealed large 



DlStKIIMION dl Htft 1 



He. I Piece of C ivtHceoiiN a/k- 



iise Ufi> ' in'" ft ptjotoj ptuckw 



by the sea from a rock outcrop, 

 then worn to Hie shape ut the 

 lU'avhed kelp holdfast ton leh 

 of photo) before being cast, 

 ashoie nor Von Mueller Creek. 

 Otway coast. Viclnna. Vis- 

 tralia. Kulcr on inch scale. 

 Fill. 2 Block of Lower Cretaceous 

 aikose from cavily shown in 

 lower pari of photograph 

 pliicU-il hy last-movtnn seas 

 fioni shoic platform M Pwrt 

 SluiL Otwaj coast, \ietoiia 

 Hock made loose by convcr 

 tciicc -.it ObtiqiC miner joint 

 planes with nraicu veriical one 

 Sirne thtee-fool niler i'^ MH 

 for scale In fig. 1 



Ooatn-r. 1971 



numbers of small fragments. If the 

 iiumbci of fionds pulling rock from 

 liic sutfacc of the outcrops is as 

 numerous as it appears by those 

 helped on the shore, then since the 

 sea rose to tts present level some 

 6.000 years ago. this process has sup- 

 plied .' significant; armoury for the 

 sc-a wilh which lo abrade the shotc 

 platforms, and made a significant 

 contribution lo the sand supplv lor 

 the beaches. 



!-.d wards 0954- 1 records boldlasi.s 

 with rocks up to 20 pounds tfeljjhl 

 heine. thrown ashore. II ihe rocks 

 plucked from a headland by kelp 

 (the heavy blocks fallen to the sea 

 Hoor plus those thrown ashore i na.il 

 on average 100 pounds or so per 

 year, then in the six millcnia since 

 the sea rose to its present general 

 level, ncarlv 100 tons of rock have 

 been removed by litis process alone 



l-BOM ROIKV SlIOKI PL\TH>KM 



Plate I figure 1 is a somcwh.it 

 liiaiigular piece of Lowei Cretaceous 

 aikose which Ihe sea plucked fivmi 

 the cavitv shown in the lowei part 

 ol the photograph. Ihe site is the 

 surface of a supralidal shore plat 

 form on the bold headland called 

 Point Stun on the Otway coast of 

 Victoria. Aiislr,.lia (sec photos and 

 section ot Point Stun in Gill 1071). 

 The shape ot the rock results from 

 the fact lhal it is I loose block 

 created by the coincidence ol some 

 lesser joint planes with a major one. 

 Ihe Hat vertical face at the back ot 

 the cavitv is the major joint plane 

 The Hat surface of the plucked block 

 that (its against thai face is the ihick 

 side out of sight iii the top of the 

 picture Ihe rock was not levered 

 In some person, or the bruises to 

 llie rock would have been evident 

 I he block was found u short distance 

 l.iuduard "f Hie cavily. and was 

 tound to lit peifectlv 1 be rush of 



289 



