A Monograph of Marcus Island. 



87 



polyp can do to build its masonry of coral rock as fast as old ocean 

 is pleased to here heap up the land-forming materials. Near the 

 north end the land attains a height of seventy-five feet, which was 

 the highest point found. In this vicinity the beach is made up of 



Fig. 4. One of the curious spaces inland on which, though surrounded by 

 dense woods, no trees or shrubs will grow. 



six successive bench-like steps. These mark the gradual reced- 

 ing beach lines and point unmistakably to successive elevations. 

 The old benches are quite uniform in chara(5ler, being twelve feet 

 deep and thirt}' or forty feet in width. Rounded blocks of coral 

 which go to make up the upper ones are often as large as a man's 

 head. Intermingled with the stones are shingle and sand of a coral 



