74 



THE FLOOR OF THE OCEAN 



140 



1145 



150' 



PA C I F / C 



OCEAN 



i\ MICHAELMAS CAY BORE 



RON ID. 

 BORE 



140 



| 145° 



150° 



FIGURE 42. MAP SHOWING LONG LAGOON INSIDE THE GREAT BARRIER REEF 

 OF AUSTRALIA, WITH LOCATION OF MICHAELMAS CAY AND HERON ISLAND. 



reaches 300 feet. Each is of the same order of distance below 

 sealevel as that reached by the bottom of the shell-coral sand 

 in Bermuda. Thus it seems clear that the association of broad 

 lagoon with peripheral reef, whether atoll or barrier, does not 

 demonstrate subsidence of the earth's crust or give a measure 

 of the strength of the sub-oceanic crust. 



