MUSEUM OF COMPARATIVE ZOOLOGY. 143 



istic reef material, and is composed to a certain extent of corals, which 

 have evidently grown in place, this reef gives proof of a recent elevation 

 of the shore to the height of about tw§nty-five feet. There has been 

 a considerable loss by corrosive action, how great cannot be determined, 

 in the height of this reef. It is throughout honeycombed by subter- 

 ranean water passages, and the surface of the rock is much disrupted by 

 the overturning of trees in times of hurricanes, when the roots entangled 

 in the crevices of the rock break blocks away from their bedding. 



The ]\Iiarai Reef, as I propose to term this interesting accumulation of 

 coral, extends northwardly with occasional interruptions for a great dis- 

 tance along the eastern shore of Florida. North of Dumbfoundling Bay 

 it appears gradually to lose its character as a true coral reef, and to take 

 ou the general nature of coquina. It appears to be the same elevation 

 that is traceable as far north as the northern part of Indian River, near 

 Titusville. I have only observed this ridge at certain points. North 

 of Lake Worth I have not observed any corals in the material. It ap- 

 pears that from Jupiter's Inlet to Titusville it is mainly composed of 

 raolluscan remains. It is therefore not certain that it is all of the same 

 age as the Miami Reef, but the fringe of beach material follows con- 

 tinuously on the line of that reef, fii-st in an almost meridional direction, 

 then turning at Lake Worth to the northwest. There can be no doubt 

 that the eastern shore of Florida from Miami to Titusville, and probably 

 all to the northward, has its position determined by the strong resist- 

 ance which this consolidated beach deposit has offered to the action 

 of the sea. 



The steep escarpment which this barrier of old beach material pre- 

 sents, which is now elevated to a score of feet or more above its original 

 position, indicates that it long withstood the beating of the ocean waves. 

 The barrier of drifting sands now lying along the coast between this 

 escarpment and the open ocean has apparently been constructed in very 

 modern times, since the last elevation of the shore. A part of the cut- 

 ting which formed the escarpments of this reef evidently took place 

 during the process of elevation which brought the reef to its present 

 altitude. This is indicated by the fact that sea caves and other re- 

 entrants are formed in the cliffs at a considerable height above the 

 present plane of the sea. 



The effect of this reef on the drainage of Florida is very great. 

 Although the rivers at many points have found their way across the 

 elevation, either by subterranean streams or through the low points of 

 the barrier, it serves to retain the land waters, and to bring into the 



