bkannee: the stoxe reefs of brazil. 



16; 



Fig. 91. Section at the village of Sao Thome'. 



Case III. Trachytic boulders (see p. 1.59). 



Hypothesis I. Hypothesis II. 



The burrows would have to be The rocks were carried beneath the 



made before the greater elevation, and water by the depression, then bur- 



the following depression would bring rowed, and later slightly elevated, 

 them within the reach of the water. 



Fig. 92. Trachyte blocks bored by sea-urchins. 

 Case IV. has reference to the eroded coral reefs (see pp. 239-245). 



Hypothesis I. Hypothesis II. 



Greater elevation would either have The depression would permit corals 



to take place before the reefs were to grow up to a depth of 150'; a small 



made, or else the reefs would all be elevation, when they were already 



killed by the elevation. The depres- near the surface, would kill them and 



sion would put them back in the allow them to be eroded, 

 water. 



Case V. is that of the terrace at Ilheos spoken of on pp. 15.3-155. 



Hypothesis I. Hijpoth^.'ti^ II. 



Necessitates the formation of the The terrace was made during the 



terrace before the elevation, and a depression, and lifted by a small 

 subsequent depression. elevation. 



