278 ALEXANDER AGASSIZ 



the thinness of the coral formations. Writing to Huxley 

 at a somewhat later date, Agassiz says : — 



" A short time ago I received from an artesian well 

 at Key West samples of rock one thousand feet from 

 the surface, entirely made up of Foraminifera, debris of 

 Mollusks, Echinoderms, and Crustacea, rock very simi- 

 lar to that now forming on the Pourtales plateau off 

 Key West in three hundred fathoms, and totally differ- 

 ent from coral reef rock, a strong probability that the 

 underlying rocks of the Florida plateau were built up 

 as I suggested from my dredgings of rock similar to that 

 of the Pourtales plateau up to the depth at which coral 

 reefs could begin to grow, when they took the promi- 

 nent part." 



The newer theories of the formation of coral reefs and 

 coral islands are chiefly associated with the names of 

 Agassiz and Murray, who were in the main in accord 

 in their ideas on the subject, though in some cases they 

 apparently differed as to the amount of work done by 

 modern corals, and seem to have placed somewhat dif- 

 ferent values on the relative efficiency of the action of 

 erosion, solution, and the scouring force of the ocean in 

 the formation of atolls and barrier reefs. Murray laid 

 much importance on the effects of solution in creating 

 lagoons and the passages between barrier reefs and the 

 land, while we shall see in Agassiz' s subsequent expe- 

 ditions the manner in which he believed them to have 

 been produced. In a letter to Huxley he says on this 

 point: "I do not believe that solution as such has pro- 

 duced the effects Murray ascribes to it. It has been a 

 factor, but a more limited one than he assumes." 



