GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 327 



6. Alexander Agassiz correctly observed the superposition of the 

 living coral reefs of the Bermudas and the Bahamas on older lime- 

 stone foundations that stood above sea level previous to the sub- 

 mergence which made possible the formation of reefs in the places 

 where they now grow. He also pointed out the superposition of the 

 Floridian, Cuban, and Central American living reefs on antecedent 

 platforms or older limestone. He showed that in several areas in the 

 Pacific the sum total of local crustal movements since some time in 

 the Tertiary period had been upward. But he failed to take account 

 of Recent submergence in Florida, the West Indies, and Central 

 America, and he advanced the hypothesis that the living offshore 

 reefs of the Pacific are superposed on wave-cut platforms without 

 change of sea level by submergence of the land. I believe Agassiz 

 correct in his emphasis of the need of an antecedent platform for the 

 vigorous growth of offshore reefs ; but he did not recognize the clear 

 evidence of Recent submergence of the shores of the reef-encircled 

 islands, and unfortunately tried to explain the formation of lagoons 

 by submarine solution and scour. 



7. E. C. Andrews, I believe, is incontrovertibly correct in the 

 essentials of his interpretation of the conditions under which the 

 Great Barrier Reef of Australia has formed; that is, it is superposed 

 on that part of the recently submerged Continental Shelf of Australia 

 that lies within the temperature zone favorable for the life of reef- 

 forming corals. 



8. Stanley Gardiner, who has made great contributions to our 

 knowledge of Indo-Pacific corals and coral reefs and whose work on 

 the oceanography of the Indian Ocean is justly rated as classic, com- 

 mitted the same errors in interpreting the geologic relations of coral 

 reefs as did Murray and Agassiz. He failed to infer submergence 

 from shore line characters and advocated the formation of lagoons 

 through submarine solution by sea water. 



9. Hedley and Griffith Taylor agreed in all the essentials of 

 Andrews's interpretation of the conditions under which the Australian 

 Great Barrier formed ; they opposed Murray's solution hypothesis for 

 the formation of lagoons, and correctly emphasized the importance of 

 currents, largely wind induced, in the shaping of the atolls along the 

 Great Barrier. 



10. Daly, did not originate the Glacial-control theory of coral 

 reefs, but he is its principal exponent. The following ascertained 

 relations of living offshore coral reefs conform to the demands of this 

 hypothesis: (a) They are superposed on antecedent basement flats; 

 (&) the amount of recent submergence, between 30 and slightly more 

 than 20 fathoms, without deducting the amount of Recent up-build- 

 ing of the sea bottom, which probably is as much as a few fathoms, 

 is of the order of magnitude expected from deglaciation; (c) the 



37149— 19— Bull. 103—10 



