296 ALEXANDER AGASSIZ 



What he saw of the elevated terraces of eastern Cuba 

 convinced him that his first examination of this coast, 

 made many years before, had led him to misinterpret 

 their true nature. In common with other naturalists, he 

 had supposed that all these elevated limestones were 

 coral reef rock, representing coral reefs perhaps twelve 

 to fifteen hundred feet thick. He was now able to satisfy 

 himself that the first terrace was a true coral reef which 

 had been elevated to a height of thirty feet or less. The 

 limestones of the second, third, and higher ten-aces, on 

 the other hand, he considered were of older age and dif- 

 ferent origin than those of the first elevated reef which 

 flanks the shore. Although he found an occasional mass 

 of a species of reef -building coral in the older limestone, 

 this did not lead him to believe that these rocks belong 

 to the group of reef-building corals, any more than he 

 woidd have spoken of a few isolated heads of reef- 

 building species found along any shore line as consti- 

 tuting a coral reef. Moreover, since he found the older 

 limestone underlying the coral reef rock of the first ter- 

 race, he was inclined to believe that the presence of the 

 fossil corals in the higher terraces might be explained as 

 the remains of a similar veneer of about the same thick- 

 ness as the first terrace, say twenty-five to thirty feet, 

 which had covered the higher terraces at the time of 

 their elevation. 



Recognizing the necessity of a more careful survey 

 by a younger man, Agassiz afterwards sent Professor 

 Robert T. Hill to investigate this question. Hill was 

 able to establish the Tertiary origin of the older lime- 

 stones of which he writes: "In fact I do not believe 

 that any of the Tertiary limestones are of reef rock 

 origin, but they are mostly organic and chemically 



